JPH02306591A - Manufacture of thin film electroluminescence element - Google Patents

Abstract

PURPOSE:To enhance luminance of a thin film electroluminescence element by forming a light emitting layer by the electron beam deposition method or resistance heating deposition method using a target which contains a compound comprising IIA or IIB group elements as base materials and VIB group elements (excepting oxygen), and a target which contains oxygen. CONSTITUTION:A light emitting layer is formed of a fluorescent material consisting of a base material comprising ZnS, CaS, SrS, ZnSe and the like which contains radiation providing elements such as transition metals, rare earth elements comprising Mn, Tb, Eu, Ce and the like, and the light emitting layer contains oxygen. The electron beam deposition method or resistance heating deposition method is employed for forming the layer. In those methods, at least two targets i.e. that formed from a base material or a base material doped with luminescence center and that containing oxygen are used simultaneously as an evaporation source.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a thin film EL device.

[Conventional technology].

Conventionally, a transparent conductive film - an optional first insulating layer.

In order to improve the luminance of a thin film EL device in which a light emitting layer, a second insulating layer and a conductive film are sequentially laminated, the light emitting layer is generally added in the manufacturing process. After the formation of
Heat treatment is performed by heating for about 2 hours (Nikkei Electronics April 1979 issue).

[Problem to be solved by the invention]

Among the conventional thin film EL devices, those using a ZnS light emitting layer to which a small amount of Mn is added as a light emitting layer and having first and second insulating layers are currently considered to exhibit the highest luminance. ing.

However, even in this thin film EL element, the luminance when emitting light by line sequential scanning with a frame frequency of several tens of Hz is 20
-730 Foot Lambert, CRT (cathode)
Compared to other devices such as ray tubes, the luminance is still insufficient for use as a practical display panel.

[Means to solve the problem]

The present invention provides a method for manufacturing a thin film EL device, in which a transparent conductive film, a light-emitting layer, and a conductive film are sequentially laminated on a transparent substrate, and an N edge film is formed between at least one of these layers. The light-emitting layer is formed by electron beam evaporation using a target containing a compound consisting of an nA group or IIB group element and a VTR group element (excluding oxygen) as a base material, and a target laser containing oxygen. The present invention relates to a method for manufacturing a thin film EL device, characterized in that it is formed by a resistance heating vapor deposition method. , the light emitting layer is made of a transition metal such as Mn, Tb, Eu, Ce,
Zn containing luminescent activating elements (luminescent centers) such as rare earth elements
S, Ca S, S r S, 7. n
It is made of a phosphor made of a base material such as S a and contains oxygen. As the forming force method, an electron beam evaporation method or a resistance heating evaporation method is used. In these methods,
At least two targets are simultaneously used as evaporation sources: a target made of the above-mentioned base material material or the above-mentioned base material doped with the above-mentioned luminescent center, and a target containing oxygen. Adding a luminescent center (
When using an undoped base material as targetera l-.

Mn5. A compound of a luminescent activating element such as MnCO2 may be used separately from the target, or Mn SO4 or MnO may be used as the oxygen-containing compound.

A compound containing a luminescent activating element such as Ce2O3 and oxygen is used. When using a base material doped with a luminescent center, the luminescent center is 0.001 to 1% of the base material.
Preferably, it is added in an amount of 0% by weight. Examples of the above-mentioned oxygen-containing compounds include ZnO, Z
There are compounds containing Group IIA or Group IIB elements and oxygen that constitute the base material, such as nSO4°ZnC01, CaSO4, and SrCO3. Sulfides are particularly preferred as the borrowing material.

The light-emitting layer obtained by electron beam evaporation method or resistance heating evaporation method has excellent crystallinity, and the degree of vacuum during evaporation is
-'' to lXl0-', it is possible to prevent the incorporation of impurities and it is easy to obtain high-brightness thin film EL elements.Also, the film formation speed can be increased, so the release layer can be formed in a short time. be able to.

The light-emitting layer created in this way has M elements introduced therein, and this oxygen is thought to play a role in filling the defects of the VTR group elements in the light-emitting layer, resulting in improved luminance.

A glass plate or the like is used as the translucent base material in the present invention.

The transparent conductive film is made of SnO2, In2O3, indium tin oxide (ITO), etc., and is made by electron beam evaporation,
Vacuum deposition method, sputtering method, CVD (Chem
ical vapor deposj, tion) method,
It is formed by a plasma CVD method or the like.

The other conductive film may be the same as the transparent conductive film, or may be made of a metal such as aluminum, chromium, or gold.

The insulating layer is made of Ta205. Y2O3,Si,02゜A
Q203. The insulating layer may be made of Si, N, AnN, 5rTiOJ, etc., and two of these layers may be laminated in two circles. The method for forming these layers is the same as the method for forming a transparent conductive film.

In the present invention, the M edge is laminated between the transparent conductive film and the light emitting layer and/or between the light emitting layer and the conductive film. Hereinafter, the insulating layer between the transparent conductive film and the light emitting layer will be referred to as a first insulating layer, and the layer between the light emitting layer and the conductive film will be referred to as a second insulating layer.

In the present invention, a transparent conductive film and a first insulating layer.

A light emitting layer, a second insulating layer, and a conductive film (back electrode) are sequentially formed on the base material in this order. However, one of the first and second insulating layers may be omitted. Also 1
After forming the light-emitting layer, an insulating layer similar to that described above may be laminated to further form a light-emitting layer.

In the present invention, after forming the light emitting layer during these steps,
200℃ under vacuum or inert gas atmosphere such as Ar, N2, etc.
Heat treatment may be performed at ~650°C.

The present invention will be explained using the drawings. FIG. 1 is a cross-sectional view showing an example of a thin film EL element obtained by the present invention, in which a transparent conductive film (transparent electrode) 2, a first insulator [3,
Luminous layer 4. It is manufactured by laminating a second insulating layer 5 and another conductive film (back electrode) 6 in this order.

Example 1 A thin film EL device having a structure as shown in FIG. 1 was fabricated.

An ITO film is formed on borosilicate glass as a base material 1 by a spun-kling method, and this is etched to form a sliver-like ITO transparent electrode (film thickness: 0.5 mm) as a transparent conductive film 2.
2 μm + @0, 15 mm, electrode spacing 0.1
mn) 320 pieces were formed. On top of this, a first insulating layer 3
As Si3N, 0.22 μm by film plasma CVD method
It was formed to a thickness of .

Next, as the light-emitting layer 4, a manganese-activated zinc sulfide (ZnS:Mn) layer was formed to a thickness of 0.6 μm by electron beam evaporation. As targets, ZnS pellets containing 0.25% by weight of Mn relative to ZnS and MnO were used.
was used to direct an electron beam at each target. The pressure inside the electron beam evaporation tank was once reduced to below 1X10-7, and then a light-emitting layer was formed. Also, the substrate temperature is 2
00°C, the deposition rate was 60n, m/min, and MnO
The evaporation rate of was controlled so that the Mn content in the film was 0.1% by weight.

Next, a Si3N film was formed as the second insulating layer 5 by sputtering to a thickness of 0.22 μm.

Finally, an AQ layer is formed by electron beam evaporation and etched to form a conductive film 6 as a back electrode of strip-like AQ (film thickness 0.2 μm, width 0.15+nm, electrode spacing 0.1 mm). 200 electrodes were formed perpendicularly to the ITO transparent electrode. The obtained thin film EL device was designated as Sample A.

Comparative Example 1 A thin film EL device was obtained in the same manner as in Example 1, except that MnS was used instead of the M n O target when forming the light emitting layer. The obtained thin film EL device was designated as Sample B.

Sample A and sample B obtained above were heated at a frequency of 150 H'
The relationship between the opening voltage (Vrms) applied between the transparent electrode and the back electrode using a cosine wave voltage of z and the luminance brightness (
Applied voltage-emission brightness characteristics) were determined.

Figure 2 shows this result. In Figure 2, graph 7 is sample A
Graph 8 is the result for sample B.

As is clear from these results, at an applied voltage 30 V higher than the emission starting voltage, the luminance of sample A was 380 c d / rr? (at 176V) and 230cd/rr for sample B? (at 174V)
Met.

Example 2 In Example 1, the light-emitting layer was made of manganese-activated zinc sulfide (ZnS) using a resistance heating evaporation method instead of an electron beam evaporation method.
:Mn) layer was formed to a thickness of 0.67zrn [However, as targets, ZnS pellets and Mn
These were evaporated simultaneously from different tungsten crucible heaters.

The pressure inside the vapor deposition tank was once reduced to 1X10-7 torr.

The substrate temperature was 200°C, and the deposition rate was 60 nm/min.
The evaporation rate of MnO was controlled so that Mn and oxygen in the film were 0.3% by weight and 0.1% by weight, respectively. ] The thin film E I was prepared in the same manner as in Example 1 except for the above.

I got the element. The obtained thin film EL device was designated as Sample C.

Comparative Example 2 In Example 2, MnS is used instead of MnO as a target (Mn in the film is 0.3 times
A thin film EL device was obtained in accordance with Example 2, except for adjusting the amount (%). The obtained thin film EL device was used as a sample.

The applied voltage-emission brightness characteristics of Sample C and Sample Sample 1 obtained above were determined in the same manner as above. As a result, at an applied voltage 30 V higher than the luminescence starting voltage, sample C exhibited luminance 1.6 times higher than that of the sample.

〔Effect of the invention〕

According to the present invention, a thin film EL element with excellent luminance can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a thin film EL device according to the present invention, and FIG. 2 is a graph showing applied voltage-emission luminance characteristics of the thin film EL devices obtained in Example 1 and Comparative Example 1. DESCRIPTION OF SYMBOLS 1... Base material, 2... Transparent conductive film, 3... First insulating layer, 4... Light emitting layer, 5... Second insulating film, 6...
- Conductive film (back electrode), 7... Graph showing the results of Example 1, 8... Graph showing the results of Comparative Example 1.

Claims (1)

[Claims] 1. In a method for manufacturing a thin film EL element, a method for manufacturing a thin film EL device includes sequentially laminating a transparent conductive film, a light-emitting layer, and a conductive film on a light-transmitting base material, and forming an insulating layer between at least one of these layers,
The above-mentioned light-emitting layer is made of a group IIA or group IIB element as a base material.
A thin film EL element formed by an electron beam evaporation method or a resistance heating evaporation method using a target containing a compound composed of a group VIB element (excluding oxygen) and a target containing a compound containing oxygen. manufacturing method.