JPH0766857B2 - Thin film EL device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The first invention contained in the present application is an improvement of a thin film EL element, and a rare earth element contained in an EL film composed of a composition of zinc sulfide and a rare earth element and a halogen element or manganese. The EL film that constitutes the thin film EL device with improved luminous efficiency and brightness characteristics by making the composition ratio of the element and the halogen element close to 1 is separated from the underlying film (lower insulating film or transparent electrode). It is an improvement to prevent.

A second invention included in the present application is an improvement in a method for manufacturing a thin film EL element, which is characterized in that a composition ratio of a rare earth element to a halogen element contained in an EL film made of a composition of zinc sulfide, a rare earth element and a halogen element is set. In order to improve the luminous efficiency and luminance characteristics close to 1, or to prevent the EL film made of a composition of zinc sulfide and manganese from having too little sulfur, the film quality of the EL film is deteriorated. An EL film is formed by using a sputtering method in which a gas containing hydrogen sulfide is used as a sputtering gas.
This is a method for manufacturing an EL film, which solves an unavoidable defect in the film manufacturing method, that is, an EL film is easily separated from a film (a lower insulating film or a translucent electrode) which is a base of the film.

The gist of the first invention and the second invention is that a bonding film made of a compound of sulfur or selenium and a group II, group III or group V element is interposed on the lower surface of the EL film.

[Industrial application field]

The present invention relates to an improvement in a thin film EL device and a manufacturing method thereof.
In particular, in order to improve luminous efficiency and luminance characteristics, the EL film and the underlying layer (lower insulating layer) in which the composition ratio of the rare earth element as the luminescent center and the halogen element contained in the base material zinc sulfide are close to 1 Thin film EL element with a structure that improves the adhesion to the film or translucent electrode), and a rare earth element and a halogen element that are the luminescent centers contained in the zinc sulfide matrix to improve the luminous efficiency and luminance characteristics. In order to bring the composition ratio close to 1 or to improve the film quality of an EL film made of zinc sulfide containing manganese as an emission center, the EL film is manufactured by using a sputtering method using hydrogen sulfide as a sputtering gas. The present invention relates to an improvement in a method of manufacturing a thin film EL element, which improves reproducibility of adhesion between an EL film and a layer (lower insulating film or translucent electrode) which is a base thereof.

[Conventional technology]

A thin film EL element is a rare earth element such as terbium, samarium, thulium, praseodymium, etc., which functions as a luminescence center, and a halogen element such as fluorine or chlorine. It is a light-emitting element that emits light based on the luminescence phenomenon, and conventionally known are a DC drive type as shown in FIG. 2 and an AC drive type as shown in FIG.

See Fig. 2. In the DC drive type thin film EL device, a transparent electrode 2 made of ITO or the like and having a thickness of about 2,000 Å is formed on a glass substrate 1 and the rare earth element that functions as an emission center is formed on the transparent electrode 2. An EL film 4 made of zinc sulfide or the like containing a combination of elements such as terbium and a halogen element such as fluorine or manganese is formed, and a counter electrode 6 made of aluminum or the like is further formed thereon.

See FIG. 3. In the AC drive type thin film EL device, in addition to the layer structure shown in FIG. 2, the EL film 4 is sandwiched between silicon oxynitride, aluminum oxide, yttrium oxide, etc. A first insulating film 3 and a second insulating film 5 having a thickness of about 2,000 Å are formed.

By the way, of the rare earth elements that function as emission centers,
Terbium emits green light, samarium emits red light, thulium emits blue light, praseodium white light, and manganese emits orange light, but their luminous efficiency and brightness are not satisfactory except for terbium. Even in the best terbium, the luminous efficiency is 0.1 to 0.2 lumen / W, and the brightness is 30 foot lambert, and it cannot be said that each of them is sufficiently satisfactory, and the reproducibility is not always good.

As a means for solving this problem, the inventor of the present invention has
There is a correlation between the composition ratio of the rare earth element contained in the film and the halogen element and the luminous efficiency / luminance characteristics, and the best luminous efficiency is obtained when the number of atoms of the rare earth element and the number of atoms of the halogen element are the same. It is effective to realize brightness and to increase the composition ratio of the rare earth element and the halogen element contained in the EL film to at least the chemical composition ratio. By discovering this, we completed the invention of a thin film EL device with excellent luminous efficiency and brightness characteristics.

Further, in a thin film EL element having an EL film made of zinc sulfide containing manganese as an emission center, when the chemical properties of manganese and zinc are similar, when manganese as an emission center is added to the base material. , The number of cations exceeds the number of anions, and the sulfur contained in the EL film becomes too small.
There is a drawback that the quality of the EL film becomes poor and the luminous efficiency and luminance characteristics deteriorate.

The purpose is to bring the composition ratio of the rare earth element, which is the emission center, to the halogen element close to 1, and to prevent the EL film quality from being deteriorated due to the addition of manganese, which is the emission center, and the emission efficiency and luminance characteristics being deteriorated. In order to realize the present invention, the present inventors have proposed a sputtering method in which a gas containing hydrogen sulfide as a part of a component is used as a sputtering gas and zinc sulfide and a rare earth element are used as targets, or hydrogen sulfide is used as a part of the component. A thin film EL device manufacturing method has been completed in which an EL film is manufactured using a sputtering method in which a gas is a sputtering gas and zinc sulfide and manganese are targets.

[Problems to be solved by the invention]

Thin-film EL element manufactured by performing the above-described method for manufacturing a thin-film EL element (method for manufacturing a thin-film EL element using a sputtering method in a sputtering gas containing hydrogen sulfide as a component) At the beginning of manufacture, the EL film is excellent enough to satisfy emission efficiency and luminance characteristics, but the EL film and its base (lower insulating film (first insulating film) in the case of AC drive type, DC drive type) In that case, there is a drawback in that the adhesiveness to the transparent electrode made of ITO or the like) is poor and the EL film is easily peeled off from the base during the handling period such as the slicing process and the mounting process.

A first object of the present invention is to improve the adhesion between an EL film and its underlayer in a thin film EL element using zinc sulfide whose EL film has a composition ratio of a rare earth element as a luminescence center and a halogen element close to 1. And the EL film does not peel off from its underlayer.
It is to provide an element.

A second object of the present invention is to improve the luminous efficiency / luminance characteristics by making the composition ratio of the rare earth element, which is the luminescent center, and the halogen element close to 1, or to improve the luminous quality by improving the film quality of zinc sulfide. In order to improve the luminance characteristics, in the method of manufacturing a thin film EL element in which an EL film is manufactured by sputtering in a sputtering gas containing hydrogen sulfide as a component, the adhesion between the EL film and its base is improved. Another object of the present invention is to provide a method of manufacturing a thin film EL device.

[Means for solving problems]

The means adopted by the present invention to achieve the above first object is as follows: (a) A transparent electrode 2 is formed on a transparent substrate 1, and an EL film is formed on the transparent electrode 2. 4 is formed, and a counter electrode 6 is formed on the EL film 4, a thin film EL element,
Alternatively, the transparent electrode 2 is formed on the transparent substrate 1, the first insulating film 3 is formed on the transparent electrode 2, and the EL is formed on the first insulating film 3. The film 4 is formed, and the second insulating film 5 is formed on the EL film 4.
In the thin film EL element in which the counter electrode 6 is formed on the second insulating film 5, (b) between the translucent electrode 2 and the EL film 4 or the first Between the insulating film 3 and the EL film 4 described above,
This is because the bonding film 7 made of a compound of sulfur or selenium and a group II, group III or group V element is interposed.

As the above-mentioned bonding film, gadolinium oxysulfide, yttrium oxysulfide, gadolinium oxyselenide, yttrium oxyselenide and the like are suitable.

The means adopted by the present invention to achieve the second object is as follows. (A) A transparent electrode 2 is formed on a transparent substrate 1, and hydrogen sulfide is formed on the transparent electrode 2. An EL film 4 made of zinc sulphide alone or a zinc sulphide composition containing a rare earth element and an alkali element or manganese is formed by using a sputtering method in which a gas containing is used as a sputtering gas, and the EL film 4 is opposed to the EL film 4. A method of manufacturing a thin film EL element in which an electrode 6 is formed, or a transparent electrode 2 is formed on a transparent substrate 1, and a first insulating film 3 is formed on the transparent substrate 1. On the insulating film 3 of No. 1, an EL film 4 made of a zinc sulfide simple substance or a zinc sulfide composition containing a rare earth element and an alkali element or manganese is used by a sputtering method using a gas containing hydrogen sulfide as a sputtering gas. And then form a second insulating film 5 on this EL film 4. , The counter electrode 6 on the second insulating film 5
In the method of manufacturing a thin film EL device for forming a film, (b) forming a bonding film 7 made of a compound of sulfur or selenium and a group II, group III or group V element prior to forming the EL film 4. is there.

As the above-mentioned bonding film, gadolinium oxysulfide, yttrium oxysulfide, gadolinium oxyselenide, yttrium oxyselenide and the like are suitable.

[Action]

It is obvious that the cause of the above-mentioned poor adhesion is due to the small chemical bonding force between the EL film material and the underlying material.

In the above case, when hydrogen sulfide comes into contact with the surface of the underlying first insulating film or the transparent electrode made of ITO or the like, sulfur is entirely attached to the surface. However, the sulfur is only adsorbed by the van der Waals force on the first insulating film as the base or the translucent electrode made of ITO or the like. In other words, sulfur is not chemically bonded to the silicon atom or the oxygen atom forming the first insulating film, the indium atom forming the ITO, the tin atom, the oxygen atom, or the like. Therefore, the EL film is peeled off from the base in the slicing process, the mounting process, and the like.

In order to eliminate this cause, together with the EL film material,
It is obvious that a bonding film made of a material that can be chemically and strongly bonded to the material of the base may be interposed between the EL film and the base.

By the way, in the thin film EL element, the material used as the base of the EL film is an insulator such as silicon oxide, silicon oxynitride, yttrium oxide, or ITO, and the material of the EL film is zinc sulfide. A material that is easily chemically bonded, that is, a material having sulfur or selenium as a constituent element, such as gadolinium oxysulfide, yttrium oxysulfide, gadolinium oxyselenide, or yttrium oxyselenide, is used as a translucent film. Between the electrode and the EL film,
Alternatively, it may be interposed between the first insulating film and the EL film. In this way, since the vapor pressure of sulfur is very high, the bond between sulfur and sulfur is not established, and the sulfur as the base component and the zinc of zinc sulfide forming the EL film are directly and strongly bonded. The EL film made of zinc sulfide does not peel off from the underlying layer.

〔Example〕

Hereinafter, with reference to the drawings, the scope of claims 2 and 5
An example of the AC drive type thin film EL element according to the embodiment of the present invention and the example of the DC drive type thin film EL element according to the embodiments of the claims 1 and 4 will be further described.

First Example A case of manufacturing an AC drive type thin film EL element will be described.

See Fig. 1a. Sputtering method is used to deposit a thickness of approximately 2,000 on the glass substrate 1.
A transparent electrode 2 made of an ITO film of Å and a first insulating film 3 made of silicon oxide or silicon oxynitride and having a thickness of about 2,000Å are formed.

Subsequently, using argon as a sputtering gas and yttrium oxysulfide as a target, a bonding film 7 made of an yttrium oxysulfide film having a thickness of about 2,000 Å is formed.

Next, an argon film containing hydrogen sulfide (5%) is used as a sputtering gas, and zinc sulfide and terbium fluoride are used as targets to form an EL film 4 having a thickness of about 6,000Å. Typical sputtering conditions are a gas pressure of 1 × 10 ^-2 torr, a power of 1 KW for a zinc sulfide target and 300 W for a terbium fluoride target, and a substrate temperature of about 230 ° C. . After film formation, heat treatment is performed at 600 ° C. for 2 hours to improve crystallinity, and at the same time, fluorine and terbium are positioned at optimal lattice positions.

Next, a second insulating film 5 made of silicon oxide or silicon oxynitride and having a thickness of about 2,000Å is formed by using a sputtering method, and further, a thickness of about 3,000Å is formed by using an evaporation method or a sputtering method. The counter electrode (back surface electrode) 6 made of the aluminum film is formed.

The EL film 4 of the thin-film EL device manufactured through the above steps is firmly chemically bonded to the base, and is not peeled off during the handling period such as the slicing step and the mounting step.
Further, the number of atoms of terbium and the number of atoms of fluorine contained in the EL film 4 are almost the same. Its brightness (1K
Fig. 4 (brightness vs. voltage relationship A of the AC drive type thin film EL element manufactured by carrying out the present example shows the brightness vs. voltage of the prior art) when driving at Hz. As shown in the graph (compared to the voltage relationship B) and compared to the conventional technique, it is significantly improved. In the figure, A indicates the value of this embodiment, and B indicates the value of the prior art. As is clear from the figure, the luminous efficiency and the luminance (luminance for a voltage exceeding the light emission threshold voltage of 30 V when driven at 1 KHz) are improved to 1.1 lumen / W and 200 foot transversal, respectively.

Second Example A case of manufacturing a DC drive type thin film EL element will be described.

See Fig. 1b As in the case of the first example, a transparent electrode 2 made of an ITO film having a thickness of about 2,000Å is formed on the glass substrate 1 by using the sputtering method.
To form.

Subsequently, using argon as a sputtering gas and yttrium oxysulfide as a target, a bonding film 7 made of an yttrium oxysulfide film having a thickness of about 500 Å or less is formed.

Next, an argon film containing hydrogen sulfide (5%) is used as a sputtering gas, and zinc sulfide and terbium fluoride are used as targets to form an EL film 4 having a thickness of about 6,000Å. Typical sputtering conditions are a gas pressure of 1 × 10 ^-2 torr, a power of 1 KW for a zinc sulfide target and 300 W for a terbium fluoride target, and a substrate temperature of about 230 ° C. . After film formation, heat treatment is performed at 600 ° C. for 2 hours to improve crystallinity, and at the same time, fluorine and terbium are positioned at optimal lattice positions.

Next, as in the case of the first example, the counter electrode (back electrode) 6 made of an aluminum film having a thickness of about 3,000 Å is formed by using the vapor deposition method or the sputtering method.

The EL film 4 of the thin-film EL device manufactured through the above steps is firmly chemically bonded to the base, and is not peeled off during the handling period such as the slicing step and the mounting step.
Further, the number of atoms of terbium and the number of atoms of fluorine contained in the EL film 4 are almost the same. The luminance (luminance for a voltage exceeding the light emission threshold voltage by 10 V) is shown in FIG. 5 (the luminance-voltage relation A of the DC drive type thin film EL element manufactured by carrying out this embodiment is the luminance-voltage relation of the prior art). As shown in the graph (compared to B) and compared to the prior art, it is significantly improved. In the figure, A indicates the value of this embodiment, and B indicates the value of the prior art. As is clear from the figure, the luminous efficiency and the luminance (the luminous threshold voltage is 10 V
Brightness against excess voltage) is 0.5 lumen / W each
And has improved to 400 foot lamberts.

Further, as a material for the bonding film, in place of yttrium oxysulfide, gadolinium oxysulfide, gadolinium oxyselenide, yttrium oxyselenide, etc. were also tried in the same manner, but exactly the same results were obtained. .

〔The invention's effect〕

As described above, sulfur or selenium and Group II, Group III or between the EL film and the translucent electrode of the thin film EL element according to the present invention or between the EL film and the first insulating film Since the bonding film made of the compound with the group V element is interposed, the EL film is strongly chemically bonded to the underlying layer and does not peel off during the handling period such as the slicing process or the mounting process. . Moreover, since the number of terbium atoms and the number of fluorine atoms contained in this EL film are almost the same, the brightness thereof is greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1a is a sectional view of an AC drive type thin film EL device according to the embodiments of claims 2 and 5 of the present invention. FIG. 1b is a sectional view of a DC drive type thin film EL device according to the embodiments of claims 1 and 4 of the present invention. FIG. 2 is a sectional view of a DC drive type thin film EL element according to the prior art. FIG. 3 is a sectional view of an AC drive type thin film EL element according to the prior art. FIG. 4 shows the luminance of the AC drive type thin film EL element according to the embodiments of claims 2 and 5 of the present invention (luminance for a voltage exceeding the light emission threshold voltage of 30 V when driven at 1 KHz). ) A graph showing a comparison between a voltage relationship A and a brightness-voltage relationship B of the related art. FIG. 5 shows the luminance (luminance for a voltage exceeding the light emission threshold voltage of 10 V) of the DC drive type thin film EL device according to the embodiments of claims 1 and 4 of the present invention versus voltage relationship A. 7 is a graph showing a comparison between a brightness-voltage relationship B of the related art and the related art. 1 ... Translucent substrate, 2 ... Translucent electrode, 3 ... First insulating film, 4 ... EL film, 5 ... Second insulating film, 6 ... Counter electrode, 7 ... Coupling film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seitake Sato 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (56) References JP 62-105393 (JP, A) JP 60- 124397 (JP, A) JP 61-260595 (JP, A) JP 62-216194 (JP, A) JP 63-6779 (JP, A)

Claims (6)

[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 the EL film (4) is formed. Thin film having counter electrode (6) formed on top
In the EL element, a coupling film (7) made of a compound of sulfur or selenium and a group II, III or V element is provided between the translucent electrode (2) and the EL film (4). A thin film EL device characterized by being interposed. 2. The transparent electrode (2) and the coupling film (7).
A first insulating film (3) and a second insulating film (5) between the EL film (4) and the counter electrode (6). The thin film EL element according to claim 1, characterized in that 3. The compound of sulfur or selenium with a group II, III or V element is gadolinium oxysulfide, yttrium oxysulfide, gadolinium oxyselenide, or yttrium acid selenide. The thin film EL element according to claim 1 or 2. 4. A zinc sulfide simple substance or a rare earth element is formed by using a sputtering method in which a transparent electrode (2) is formed on a transparent substrate (1) and a gas containing hydrogen sulfide is used as a sputtering gas. In the method for producing a thin film EL element, an EL film (4) made of a zinc sulfide composition containing a halogen element or manganese and a counter electrode (6) is formed on the EL film (4). II) prior to formation of 4) with sulfur or selenium
A method for manufacturing a thin film EL device, which comprises forming a coupling film (7) made of a compound with a group III, group III or group V element. 5. The transparent electrode (2) and the coupling film (7).
A first insulating film (3) and a second insulating film (5) between the EL film (4) and the counter electrode (6), respectively. A method of manufacturing a thin film EL element according to claim 4. 6. The compound of sulfur or selenium with a Group II, Group III or Group V element is gadolinium oxysulfide, yttrium oxysulfide, gadolinium oxyselenide, or yttrium acid selenide. The method for manufacturing a thin film EL element according to claim 4 or 5.