JPS5914875B2 - Manufacturing method of thin film EL element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes EL (Electro
This invention relates to a method for manufacturing a thin film EL device that emits light (luminescence).

Conventionally, for AC-operated thin-film EL elements, a high electric field (about 10°V/cm) is regularly applied to the light emitting layer, and a field of 0.1
~2.0w% Mn (or Cu; Al, Br
A three-layer structure ZnS:Mn (or ZnSe:Mn) EL device was developed in which a semiconductor light-emitting layer made of ZnS, ZnSe, etc. doped with dielectric materials such as Y2O3, TiO2, etc. was developed, and improvements in various light-emitting properties were confirmed. It is being

This thin film EL element emits light with high brightness when an alternating current electric field of several kilohertz is applied, and has a long lifespan. Furthermore, the light emission of this thin film EL element has a hysteresis characteristic in which the luminance of the light emitted by the same applied voltage differs in the process of increasing the applied voltage and in the process of decreasing the applied voltage from the high voltage side. In the process of increasing the applied voltage to a thin film EL element with this hysteresis characteristic, when light, electric field, heat, etc. are applied, the thin film EL element changes to a state of light emission brightness corresponding to the intensity. The so-called memory phenomenon, in which the luminance remains high even when the light, electric field, heat, etc. Ivy. FIG. 1 shows the basic structure of a ZnS:Mn thin film EL device as an example of a thin film EL device. The structure of the thin film EL element will be explained in detail based on the attached drawings. A transparent electrode 2 such as ln2o3, sno2, etc. is placed on a glass substrate 1, and Y2O3, TlO2, Al2O3,
A first dielectric layer 3 made of Si3N4, SiO2, etc. is formed in an overlapping manner by sputtering or electron beam evaporation.

A ZnS light emitting layer 4 is formed on the first dielectric layer 3 by electron beam evaporation of ZnS:Mn sintered pellets. At this time, the ZnS:Mn sintered pellets used for vapor deposition are pellets in which the concentration of Mn, which is an active substance, is set to suit the purpose. A second dielectric layer 5 made of the same material as the first dielectric layer 3 is provided on the ZnS light emitting layer 4.
are laminated, and a back electrode 6 made of Al or the like is further formed by vapor deposition thereon. The transparent electrode 2 and the back electrode 6 are connected to an AC power source 7, and the thin film EL element is driven. electrode 2,
When an AC voltage is applied between the dielectric layers 3 and 5 on both sides of the ZnS light emitting layer 4, the AC voltage is induced between the dielectric layers 3 and 5 on both sides of the ZnS light emitting layer 4. Electrons that are excited and accelerated by the band and have obtained sufficient energy directly excite the Mn emission center, and the excited Mn
When the n-emission center returns to its ground state, it emits yellow-orange light.

That is, when the electrons accelerated by a high electric field excite the electrons of the Mn atoms that have entered the Zn site, which is the luminescent center in the ZnS luminescent layer 4, and fall to the ground state, the electrons emit light in a wide wavelength range with a peak of approximately 5,850 psi. Exhibits strong luminescence. When a rare earth fluoride other than Mn is used as the active substance, green and other luminescent colors characteristic of this rare earth element can be obtained. The thin film EL element having the structure described above can be used as a flat thin display device that takes advantage of the advantages of the NuPace factor, and can be used to display characters, symbols, still images, etc. It can be used as a means of displaying moving images, etc.

Thin-film EL panels as flat flat display devices have a lower operating voltage than conventional cathode ray tubes (CRTs), and are superior in weight and strength compared to plasma display panels (PDPs), which are also flat display devices. It has a wider operating temperature range than liquid crystal display (LCD).
It has many advantages such as fast response speed. Furthermore, since it can be used as a pure solid matrix type panel, it has a long operating life, and its address accuracy makes it very effective as an input/output display means for computers and the like. In the process of forming a light emitting layer by vapor deposition or the like, if the adhesion coefficient of the light emitting layer has substrate temperature dependence as shown in Figure 2,
By locally heating the deposition substrate side, the light emitting layer can be selectively deposited on the substrate surface.

Therefore, in the thin film EL element having the structure shown in FIG. 1, a thin film E is formed in which a light emitting layer is formed at an arbitrary position and another light emitting layer is formed by base evaporation on the surface area where the light emitting layer is not formed.
It also becomes possible to obtain an L element. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a thin-film EL device that can selectively form a plurality of types of light-emitting layers whose adhesion coefficients are dependent on substrate temperature and obtain multicolor light emission.

Hereinafter, one embodiment of the present invention will be explained in detail with reference to the drawings.

FIG. 3 is an explanatory diagram of the manufacturing process of a thin film EL device showing one embodiment of the present invention.

As shown in FIG. 3a, strip-shaped transparent electrodes 2 constituting a group of matrix electrodes are arranged in parallel on a Galanu substrate 1, and a current is applied independently to each line of the transparent electrodes 2. The transparent electrode 2 functions as a heating element, and a temperature distribution is obtained on the surface of the Galanus substrate 1.

Incidentally, the transparent electrode 2 is covered with a dielectric layer 3 as shown in FIG. 3b. By controlling the amount of current applied to each line, a temperature distribution is formed on the surface of the Galanu substrate 1, as shown in FIG. When a first light-emitting layer having luminescent color A is layered by vapor deposition on the dielectric layer 3 on which this temperature distribution is formed, the temperature becomes as shown in FIG. 3d from the relationship between the adhesion coefficient and substrate temperature in FIG. The first light emitting layer 4a is selectively formed in a region where the temperature is low (not heated by electricity). Next, a temperature distribution different from that shown in FIG. 3c is formed, and a second light-emitting layer 4b having luminescent color B is formed again by vapor deposition as shown in FIG. 3e. Similarly, the third and fourth light emitting layers can be sequentially and selectively formed on the same plane or overlapping the previous light emitting layer. By covering these light-emitting layers with a second dielectric layer 5 and arranging strip-shaped back electrodes 6 that constitute a pair of matrix electrodes in parallel in a direction orthogonal to the transparent electrodes 2, different luminescent colors A can be obtained. , B can be obtained. In addition, in the above embodiment, the light emitting layers 4a, 4
In addition to heating the transparent electrode 2, other external heating means such as high-frequency induction heating can be used to form the temperature distribution during vapor deposition.

As explained in detail above, according to the present invention, a plurality of light-emitting layers exhibiting different luminescent colors can be selectively and easily obtained by stacking them on the same plane or on other light-emitting layers.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic structure of a thin film EL element. FIG. 2 is an explanatory diagram illustrating the dependence of the light-emitting layer adhesion coefficient on the substrate temperature. FIG. 3 is a manufacturing process diagram of a thin film EL device, explaining one embodiment of the present invention. 2...Transparent electrode, 3...First dielectric layer, 4a...
First dielectric layer, 4b... Second dielectric layer.

Claims (1)

[Scope of Claims] 1. In a method for manufacturing a thin film EL device comprising a light-emitting layer that emits EL light upon application of a voltage, a temperature distribution is provided on the surface of the substrate on which the light-emitting layer is formed by vapor deposition, and the light-emitting layer A method for manufacturing a thin film EL device, characterized in that the light-emitting layer is selectively vapor-deposited in accordance with the temperature distribution by forming a region having a temperature equal to or higher than the deposition limit temperature. 2. The method for manufacturing a thin film EL device according to claim 1, wherein a temperature distribution is formed by heating a transparent electrode provided on a substrate with electricity. 3. The method for manufacturing a thin film EL device according to claim 1 or 2, wherein a plurality of light emitting layers exhibiting different EL emissions are selectively vapor deposited individually in accordance with temperature distribution.