JPS62113385A - Manufacture of thin film el device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] While reducing the driving voltage of a thin 151-inch EL element, the E
This is an improvement in the manufacturing method of a thin film EL element that makes it possible to improve the crystallinity of the L film and improve the luminous efficiency and brightness.

To reduce the driving voltage of thin film EL elements.

The lower region of the EL film (the region in contact with the first insulating film) is made to have a low resistance, the potential of the entire region is made the same potential, and the potential is operated as if this layer does not exist. In order to reduce the voltage, a zinc sulfide film is formed on the first insulating film, and ions of group II or group III elements such as aluminum are implanted into the film to convert it into a low-resistance zinc sulfide film. In addition to reducing the driving voltage,
Since the EL film is formed continuously from the zinc sulfide films 11 (zinc sulfide film with reduced resistance), its crystallinity is improved and luminous efficiency and brightness are improved.

[Industrial application field]

The present invention relates to a method for manufacturing a thin film EL element.

In particular, the present invention relates to a method for manufacturing a thin film EL element that reduces driving voltage and simultaneously improves crystallinity of EL@ to improve luminous efficiency and brightness.

[Conventional technology]

Thin-film EL elements emit light based on the electroluminescence phenomenon by applying an electric field to a polycrystalline thin film of a phosphor such as zinc sulfide containing manganese or a rare earth element such as terbium trichloride or terbium trichloride, which functions as a luminescent center. Conventionally, a structure as shown in FIG. 2 is known as a light emitting element.

Refer to Figure 2. Made of ITO, etc., on a glass substrate etc. with a thickness of approximately 2.0 mm.
The first transparent electrode 2 is made of silicon oxynitride and has a thickness of approximately 2,000 mm.
0 Forming the first insulating film 3 using sputtering method
Next, an EL film 5 made of zinc sulfide containing manganese or a rare earth element such as terbium trifluoride or terbium trichloride, which functions as a luminescent center, is deposited to a thickness of about 5,000 mm.

A second insulating film 6 made of silicon oxynitride or the like and having a thickness of about 2,000 is formed by performing heat treatment at a temperature of about 500° C. for about 1 hour and again using the sputtering method. Thereafter, a counter electrode 7 made of aluminum is formed.

[Problem that the invention seeks to solve]

The luminous efficiency and brightness characteristics of thin-film EL elements are determined by ELWl!, which is made of zinc sulfide containing manganese or a rare earth element such as terbium trifluoride or terbium trichloride, which functions as a luminescent center. However, since the crystallinity of the zinc sulfide film is easily influenced by the surface condition of the base, ELi1 of the thin film EL element according to the prior art mentioned above.
The crystallinity of 5 tends to be poor near the area where it contacts the insulating film 3, resulting in a so-called dead layer.Although this dead layer does not function as the ELI 151, it is an electric field path, so it increases the driving voltage. It only has an effect. In other words, it can be said that this region exists only to require unnecessary drive voltage. Therefore, in order to achieve sufficient luminous efficiency and brightness characteristics, it is necessary to apply an extra drive voltage corresponding to this wasted drive voltage.

Generally, the dead layer thickness is approximately 2,000 to 4.00 mm
0 people, and the above-mentioned wasted driving voltage is 30 to SOV.

As a result, the drive voltage of the thin film EL element according to the prior art is generally about 230V. However, on the other hand, the voltage of the drive circuit according to the prior art is about 200 V, and the drive voltage of the thin film EL element is only 30 V, but it exceeds this, so a high voltage circuit has to be used. , which is extremely inconvenient in practice. If the drive voltage of the thin film EL element is about 200V,
The following is true rJ f[112el+Il
l)'c I-) -Store I-1-? e1.
% By the way, if the lower region of ELllI (the region in contact with the first insulating film) that constitutes the thin film EL element is made low in resistance, the potential of the entire region will be the same, and in terms of potential, it will be as if this It is believed that the layer behaves as if it were not present and the driving voltage decreases.

However, since group II-VI compound semiconductors have a remarkable self-charge compensation effect, for example, when a group II or group III element such as aluminum, which can serve as a donor, is introduced, acceptors due to lattice defects are generated and the resistance becomes low. This phenomenon is similar when introducing an acceptor. In short, due to the self-charge compensation effect, it is not so easy to make the resistance low and to embody the above idea.

There are difficulties to overcome.

The present invention has been made in view of such an FV situation, and its purpose is to provide a method for manufacturing a thin-wall type EL element that can reduce driving voltage and improve luminous efficiency and brightness. It's about doing.

[Means for solving problems]

The means taken by the present invention to achieve the above object is in a method for manufacturing a thin film type EL element.

After forming the first insulating film 3, a zinc sulfide film 41 is formed thereon, and a group II or group III element is ion-implanted into it (in order to prevent the occurrence of self-charge compensation in a non-equilibrium state). The zinc sulfide film 41 is converted into a low-resistance zinc sulfide film 4, and zinc sulfide and rare earth elements are added onto the low-resistance zinc sulfide film 4. Alternatively, the EL film 5 is formed of an M1 compound with manganese. The thickness of the zinc sulfide film to be reduced in resistance is approximately 2,000, which would be a dead layer unless the present invention is used.

Furthermore, aluminum is the most practical element of group II or group III to be ion-implanted.

In particular, 11!41 of zinc sulfide formed on the first insulating film
When the zinc sulfide film 41 is formed using the vacuum evaporation method, the film quality of the zinc sulfide film 41 is good, so the film quality of the EL film formed thereon is also good, and the sputtering method, which has a high deposition rate, is used. [Function] The crystallinity of the zinc sulfide film is easily affected by the surface condition of the underlying film, and if the underlying film is made of zinc sulfide such as glass, If the crystal structure differs from that of the base, the crystallinity of the zinc sulfide film formed on the base will deteriorate, especially in the vicinity of the contact area, resulting in a so-called dead layer, and this dead layer may appear as though it does not perform the EL film function. As mentioned above, only unnecessary drive voltage is required.

Therefore, if this dead layer region is made low in resistance,
Since the potential is constant in that region, applying a parallel electric field will not cause a voltage drop, so the potential will behave in the same way as if this region did not exist.

By the way, since II-Vl group compound semiconductors have a remarkable self-charge compensation effect, for example, when an element that can become a donor (acceptor) is introduced, acceptors (donors) due to lattice defects are generated and the n-type (p-type) is generated. ), and as mentioned above, it is difficult to reduce the resistance.

However, as a method effective for inhibiting the self-charge compensation effect, a method of introducing a donor or acceptor in a non-equilibrium state is known. Therefore, as one aspect of this method, an ion implantation method is used to introduce a group I or group II element such as aluminum.

Therefore, a low-resistance zinc sulfide film (119! approximately 2,000 mm thick) was developed.
0 persons) using a vacuum evaporation method, aluminum was ion-implanted at an acceleration voltage of eV and a dose of 1O18/cm2 to lower the resistance of the zinc sulfide film, and sputtering was performed on this film. EL using the method
When we checked the prototype manufactured by forming a film, we found that
Compared to the conventional technology, the driving voltage is lowered by about 40V, the X-ray diffraction intensity of the EL film is about 5 times higher, and the luminous efficiency is lower.
It was 1.2 lumens/W.

〔Example〕

Hereinafter, a method for manufacturing a thin film type EL element according to an embodiment of the present invention will be further explained with reference to the drawings.

Using the sputtering method as shown in FIG.
A transparent electrode 2 made of ITOIII of 000 A is formed.

A first insulating film 3 made of a silicon oxynitride film having a thickness of approximately 2,000^ is formed using the spar and nitride method again.

Using a vacuum evaporation method, a zinc sulfide film 41 is deposited to a thickness of about 2,000 yen.
After forming 0008, aluminum is formed into 10QK.
With an accelerating voltage of eV, the dose is 1018/C11
After ion implantation as step 2, heat treatment is performed to convert the film into a zinc sulfide film 4 with low resistance.

Next, using a sputtering method, terbium fluoride
Heat treatment is performed at a temperature of 00° C. for about 1 hour to form the EL film 5. Since this EL film 5 is formed on the zinc sulfide film 4 (a zinc sulfide film with reduced resistance), there is no dead layer and it has good orientation and crystallinity.

Furthermore, a second insulator W16 made of a silicon oxynitride film with a thickness of approximately 2,000 wafers is formed using a sputtering method.

Finally, using the sputtering method, the aluminum electrode 7 is
is formed to complete a thin film type EL element.

Into the zinc sulfide film 4 in the lower region of the EL1515, which constitutes the thin-film EL device manufactured through the above steps, an element of group 1 or group 2, such as aluminum, is introduced in a non-equilibrium state using an ion implantation method. This prevents the occurrence of self-charge compensation, and the resistance in this region is extremely small. When voltage is applied, the entire region has the same potential, so it does not cause unnecessary drive voltage. Moreover, since the EL film 5 is formed on the zinc sulfide 1194, the entire area is extremely crystalline.

As a result of prototyping and measuring the thin film type EL element according to the above example, its driving voltage was 190V, and the luminous efficiency was also 1.2, which was confirmed to be about 40V lower than that of the conventional technology. lumen/W, which is 12 times higher than the conventional technology with the same driving voltage. In addition, the X-ray diffraction intensity is also compared to conventional technology.

This is an improvement of about 5 times. Moreover, the reproducibility is also extremely good. Note that the above drive voltage (190V) is lower than the voltage (200V) of the general drive circuit according to the prior art mentioned above, and there is no need to use a high voltage circuit, so the practical benefits are extremely large.

〔Effect of the invention〕

As will be explained below, in the method for manufacturing a thin film EL device according to the present invention, after forming a first insulating film, a film of zinc sulfide is formed on the first insulating film, and a zinc sulfide film is formed thereon. Alternatively, the zinc sulfide film is converted into a low-resistance zinc sulfide film by ion-implanting the group III element (introducing the group III or group III element while preventing the occurrence of self-charge compensation in a non-equilibrium state), Since ELII made of a composition of zinc sulfide and a rare earth element or manganese is formed on this low-resistance zinc sulfide film, the occurrence of self-charge compensation is effectively prevented, and the sulfide under the EL film is The zinc film has a sufficiently low resistance, and when a voltage is applied, the entire region has the same potential, so it does not cause unnecessary driving voltage.Moreover, the EL [is formed on the zinc sulfide film] Therefore, no dead layer occurs and the entire area is an extremely excellent crystal.

These effects add up to 41!71, resulting in a thin film EL element with low driving voltage and excellent luminous efficiency and brightness characteristics.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a thin film type EL element according to the present invention. FIG. 2 is a cross-sectional view of a thin film type EL element according to the prior art. l-Φ・Transparent substrate (glass substrate), 2...Transparent electrode (ITO electrode), 3ee・First insulating film (
4. Low resistance zinc sulfide film, 41... Zinc sulfide film ion-implanted with ■ or ■ group elements (aluminum), 5. Fist◆EL
@, 6... second insulating film (silicon oxynitride film),
7. Opposite electrode (aluminum electrode).

Claims (1)

[Claims] [1] A transparent electrode (2) is formed on a transparent substrate (1), and a first insulating film (3) is formed on the transparent electrode (2). After forming a zinc sulfide film (41) on the first insulating film (3), a group II or group III element is ion-implanted to make the zinc sulfide film (41) have a low resistance. zinc sulfide film (
4), an EL film (5) made of a composition of zinc sulfide and a rare earth element or manganese is formed on the low-resistance zinc sulfide film (4), and a second film is formed on the EL film (5). 1. A method for manufacturing a thin film EL element, comprising: forming an insulating film (6), and forming a counter electrode (7) on the second insulating film (6). [2] The method for manufacturing a thin film type EL device according to claim 1, wherein the group III or group VII element to be ion-implanted is aluminum.