JPS63230869A - Production of thin film el device - Google Patents

Abstract

PURPOSE:To produce a thin film EL device having improved luminescence efficiency and luminance characteristics by using an evaporating source made of the sulfide of a group II element, an evaporating source made of the sulfide of a rare earth element and a halogen-contg. gas as a reactive gas to form an EL film. CONSTITUTION:A transparent electrode 2 made of an ITO film and a first insulating film 3 of silicon oxynitride are formed on a glass substrate 1 by sputtering. The substrate 1 is then rotated in a sputtering device, a film is formed at about 0.02Torr degree of vacuum with a zinc sulfide target, a diterbium trisulfide target and a gaseous HF-Ar mixture as a reactive gas and the formed film is converted into an EL film 4 by heat treatment at about 450 deg.C for about 1hr. At this time, Tb and F are deposited on the film 3 in about 1:1 ratio. A second insulating film 5 of silicon oxynitride and a counter electrode (rear electrode) 6 of Al are further formed on the EL film 4 by sputtering.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This is an improvement in the manufacturing method of a thin film EL element, and is an improvement that improves the luminous efficiency and brightness characteristics of the thin film EL element. ′ By controlling the composition ratio of the rare earth element and halogen element added as a luminescent center to the group III element that forms the base material, it is possible to make the sulfide of the group III element the base material and the halide of the rare earth element as the luminescent center. Taking advantage of the newly discovered property that the luminous efficiency and brightness of thin film EL elements can be controlled, the composition ratio of the rare earth element and the halogen element can be changed from the stoichiometric composition ratio to the composition ratio of the rare earth element. This is an improvement of the method for manufacturing a thin 1L IEL element with increased size and improved luminous efficiency and luminance characteristics, and includes an evaporation source made of a sulfide of a group III element, such as zinc, calcium, or strontium, and a sulfide of a rare earth element. (ELI) using an evaporation source consisting of at least a halogen element or a halide as a reactive gas, such as a sputtering method or an ion plating method! 2 is a method for manufacturing a thin film EL element, characterized by forming a thin film EL element.

[Industrial application field]

The present invention relates to an improvement in a method for manufacturing a thin film EL device that makes it possible to improve the luminous efficiency and brightness of the thin film EL device. Furthermore, the present invention relates to an improvement in a method for manufacturing a thin 1]5 IEL element, which allows the luminous efficiency and brightness of the thin 1]1 EL element to be selected to desired values within a realizable size range.

[Conventional technology]

The thin film ELI element is made of a phosphor such as zinc sulfide containing a rare earth element, such as cerium, europium, terbium, samarium, thulium, praseodium, etc., which functions as a luminescent center, and a halogen element, such as fluorine, chlorine, boron, etc. A light-emitting element that emits light based on the electroluminescence phenomenon by applying an electric field to a polycrystalline thin film.
Conventionally, a DC drive type as shown in FIG. 2 and an AC drive type as shown in FIG. 3 are known.

Refer to Figure 2. For DC drive type thin film EL elements, glass substrates etc.
On top of this, a transparent electrode 2 made of ITO or the like and having a thickness of about 2,000^ is formed, and on top of that is formed an ELll141 made of zinc sulfide or the like containing a rare earth element such as terbium and a halogen element such as fluorine, which functions as a luminescent center. is formed, and furthermore, a counter electrode 6 made of aluminum or the like is formed thereon.

Refer to Figure 3. In addition to the layer structure shown in Figure 2 above, the AC drive type thin film EL element consists of silicon oxynitride, aluminum oxide, yttrium oxide, etc. with EL1g141 in between, and has a thickness of approximately 2,000 people 1st insulation 1] 3 and 2nd
An insulating film 5 is formed.

By the way, among the rare earth elements that function as luminescent centers,
Terbium emits green light, samarium europium emits red light, cerium thulium emit blue light, and praseodium emits white light, but the luminous efficiency and brightness of all of them are unsatisfactory, except for terbium.

Even in the most excellent terbium, the luminous efficiency is 0. IPo, 2 lumens/W, and.

The brightness is 5 foot lamberts when driven at 60 Hz, which is hardly satisfactory, and the reproducibility is poor.

Furthermore, since each of the three primary colors does not have the same intensity, it is difficult to create a color image using additive color mixing.

As a means to solve this problem, the inventors of the present invention
There is a correlation between the composition ratio of rare earth elements and halogen elements contained in the L film and luminous efficiency - brightness, and when the number of atoms of the rare earth element and the number of atoms of the halogen element are the same, the luminous efficiency is the best.・In order to achieve high brightness, it is effective to increase the composition ratio of rare earth elements and halogen elements contained during EL film removal, at least compared to the stoichiometric composition ratio. After discovering something, he completed the invention of a thin film EL element with excellent luminous efficiency and brightness.

[Problem that the invention seeks to solve]

The usual method for manufacturing the thin film EL device according to the above-mentioned invention is to combine a halide of cerium, europium, samarium, praseodymium, terbium, or thulium, which is the luminescent center, and zinc sulfide, calcium sulfide, or sulfide, which is the base material. Using two strontium evaporation sources or
Alternatively, the ELI 151 is formed using a vacuum evaporation method, a sputtering method, or an ion plating method using an evaporation source made of a mixture of these. In this method, the ratio of the number of atoms of the halogen element to the number of atoms of the rare earth element cannot be reduced to 2 or less, and therefore, as described above, it is not possible to obtain sufficiently satisfactory characteristics in terms of luminous efficiency and at least once.

The purpose of the present invention is to eliminate these drawbacks,
? ,1]1! The object of the present invention is to provide an improvement in a method for manufacturing a thin film EL element that makes it possible to improve the luminous efficiency of the EL element by 1]8 degrees.

Furthermore, if the thickness of the ELM is made sufficiently thick, the thin film EL
Improvement of the manufacturing method of thin-film EL elements that allows the luminous efficiency and brightness of the element to be selected to a desired value for each color within the range of realizable size, and facilitates the realization of color images using an additive color mixing method. Our goal is to provide the following.

[Means for solving problems]

The means taken by the present invention to achieve the above object are:
Using an evaporation source consisting of a sulfide of a group element, in particular zinc, calcium, or strontium, and an evaporation source consisting of a sulfide of a rare earth element, a gas containing at least a halogen element or a halide, such as fluorine or fluorine, is used. hydrogen chloride.

Deposition methods using sulfur difluoride, chlorine fluoride, chlorine trifluoride, iodine up, hydrogen chloride, chlorine, hydrogen bromide, or hydrogen iodide as a reactive gas, such as sputtering or ion plating. The objective is to use this method to form an EL film.

The present invention is based on ELII! In the B film EII of the DC drive type in which J4 is not sandwiched between the upper and lower insulating films 3 and 5, and in the #III of the AC drive type in which the ELM4 is sandwiched between the upper and lower insulating films 3.5! It is also possible to realize a 2EL element.

[Effect]

The basic idea of the present invention is that ELII9 contains a sulfide of a group Ⅰ element, particularly a sulfide of zinc, calcium, or strontium as a base material, and a rare earth element and a halogen element are added as luminescent centers. The purpose is to set the composition ratio of rare earth elements and halogen elements to tit.

By the way, in order to form an EL film using a sulfide of a group III element, particularly zinc, calcium, or strontium as a base material, and having a rare earth element and a halogen element as luminescent centers,
■ Sulfides of group elements, especially zinc, calcium, or
It is most practical to use vacuum evaporation, sputtering, or ion plating using strontium and rare earth halides as sources. However, the composition ratio of a compound of a rare earth element and a halogen element, such as terbium trifluoride, is not l = 1. Therefore, an EL film formed using such a source cannot contain a halogen element. They tend to contain large amounts of. Therefore, in the present invention, the rare earth element is supplied as an evaporation source made of its sulfide, and the halogen element is supplied as a gas containing at least a halogen element or a halide. By controlling the density etc., the amount of rare earth elements added and the amount of halogen elements added can be independently and freely controlled and selected. A rare earth element supplied from an evaporation source made of a sulfide of a rare earth element reacts with a halogen element or a gas containing a halide as a reaction gas on the evaporation source, in the plasma space, or on the substrate to form a rare earth element. The halogen element is deposited on the substrate in a composition ratio of l:l, and as a result, the amount of rare earth element added increases, making the composition ratio of rare earth element and halogen element 1:l. Can be done.

According to the experimental results, the brightness was improved by about 1.5 times compared to the conventional technology.

〔Example〕

With reference to the following drawings, 11 thin film E according to an embodiment of the present invention.
The method for manufacturing the L element will be further explained.

See Figure 1 As a sputtering target for forming ELII5I.

A zinc sulfide target and a diterbium sulfide target are used, and a mixed gas of hydrogen fluoride and argon is used as a reaction gas.

Using a sputtering method, a thickness of about 2,0
A transparent electrode 2 made of OOA ITO II 9 and a first insulating film 3 made of silicon oxynitride to a thickness of approximately 2,000 mm are formed.

Next, using a sputtering device δ that has two targets and can rotate the substrate, a sputtering method using the above source and the above reaction gas is used at a vacuum degree of 0.0:) Torr. to form a sputter and have a thickness of about e, ooo.
After forming the film A, heat treatment is performed at about 450° C. for about 1 hour to form EL@4. In this process, terbium supplied from a niterbium trisulfide target is placed on the target, in the plasma space, or in the substrate.
In Hi.

It reacts with hydrogen fluoride as a reactive gas, and is deposited on the substrate in a composition ratio of terbium and fluorine of 1:1.

According to the experimental results, in the case of 13.58MHz (7), 0.
At 51 cm-2, the composition ratio of terbium and fluorine is l:l, and the brightness is 7.5 when driven at 80 Hz.
The brightness was improved by about 1.5 times compared to the conventional technology. Further, at this time, it has been confirmed that the power density applied to the zinc sulfide target is 2 at %, which is the optimum luminescent center concentration at 2 Wcm-2.

Next, a second insulating film 5 made of silicon oxynitride and having a thickness of about 2,000 wafers is formed using a sputtering method, and a counter electrode (made of aluminum) is formed using a vapor deposition method or a sputtering method. A back electrode) 6 is formed.

According to the experimental results, the EL film 4 of the thin 1]g EL device manufactured through the above process has a composition ratio of tit at 13.541 MHz, a luminance of 7.5 foot lambert when driven at 80 Hz, The brightness was improved by about 1.5 times compared to the conventional technology.

〔Effect of the invention〕

As explained above, in the method for manufacturing a thin film EL device according to the present invention, a sulfide of a group (Ⅰ) element is used.

In particular, an evaporation source consisting of zinc, calcium, or strontium and an evaporation source consisting of a sulfide of a rare earth element are used, and a gas containing at least a halogen element or a halide, such as fluorine, hydrogen fluoride, difluoride, etc. is used. Sulfur, chlorine fluoride.

Chlorine trifluoride, iodine heptafluoride, hydrogen chloride.

Since the EL film is formed using a deposition method using chlorine, hydrogen bromide, or hydrogen iodide as a reaction gas, such as sputtering or ion plating, rare earth element atoms are The number and the number of atoms of the halogen element are always the same, and it is possible to manufacture a LiMEL element with excellent luminous efficiency and even brightness. Roughly speaking, if the thickness of ELl19 is made sufficiently thick, it becomes thin 1] 1E
aiIM of a size that can achieve the luminous efficiency and brightness of an L element
Accordingly, it is possible to manufacture a thin 18 IBL element which allows a desired value to be selected for each color and facilitates the realization of an additive color mixing method color image.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of an AC-driven thin film EL device according to an embodiment of the present invention. FIG. 2 is a structural diagram of a DC-driven thin film EL device according to the prior art. Figure 3 shows an AC-driven thin model according to the prior art. FIG. 2 is a structural diagram of an IEL element. 1... Transparent substrate (glass substrate), 2... Transparent electrode (ITO electrode). 3... first insulating film (silicon oxynitride), 4...
EL film according to the present invention (composition of fE zinc oxide, rare earth element, and halogen element), 41... ELII51 according to prior art (composition of zinc sulfide, rare earth element, and halogen element), 5... Second insulating film (silicon oxynitride), 6...
Counter electrode (back electrode). Figure 2 Figure 3 Figure 1

Claims (1)

[Claims] [1] A transparent electrode (2) is formed on a transparent substrate (1), an EL film (4) is formed on the transparent electrode (2), and an EL film (4) is formed on the transparent electrode (2). Thin film EL forming a counter electrode (6) on the EL film (4)
In the method for manufacturing an element, the EL film (4) uses an evaporation source made of a sulfide of a group II element and an evaporation source made of a sulfide of a rare earth element, and evaporates a gas containing at least a halogen element or a halide. A method for manufacturing a thin film EL device, characterized in that it is formed using a deposition method using a reactive gas. [2] First insulating film (3) sandwiching the EL film (4)
2. The method for manufacturing a thin film EL device according to claim 1, further comprising the step of forming a second insulating film (5) and a second insulating film (5). [3] The method for manufacturing a thin film EL device according to claim 1 or 2, wherein the deposition method is a sputtering method. [4] The method for manufacturing a thin film EL device according to claim 1 or 2, wherein the deposition method is an ion plating method. [5] The Group II element is zinc, calcium, or
The thin film E according to claim 1, 2, 3, or 4, characterized in that it is strontium.
Method for manufacturing L element. [6] The halogen element or halide includes fluorine, hydrogen fluoride, sulfur difluoride, chlorine fluoride, chlorine trifluoride, iodine heptafluoride, hydrogen chloride, chlorine, hydrogen bromide,
Alternatively, the method for manufacturing a thin film EL element according to claim 1, 2, 3, 4, or 5, wherein hydrogen iodide is used. [7] Claims 1, 2, 3, and 4, wherein the rare earth element sulfide is cerium, europium, samarium, praseodymium, terbium, or thulium. , Section 5, or Section 6
A method for manufacturing a thin film EL device as described in Section 1.