JP2721076B2 - Thin film EL panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film EL (electroluminescence) panel capable of supporting multicolor display, and more particularly to a thin film EL panel capable of supporting multicolor display using an organic color filter.

[0002]

2. Description of the Related Art A method using a color filter made of an inorganic material or an organic material has been proposed as one of methods for realizing a color thin film EL panel capable of multicolor display. The color filter made of the above-mentioned inorganic material is a laminated film utilizing the interference effect of light, and has problems that it is difficult to perform fine processing and that the display has a viewing angle dependence. On the other hand, an organic color filter made of an organic material does not have the above-described problem, is widely used in LCDs (liquid crystal display devices), and is relatively inexpensive.

[0003] By the way, currently commercialized thin film EL
The panel generally has a configuration in which a transparent electrode, an insulating layer, a light emitting layer, an insulating layer, and a back electrode are sequentially laminated on a transparent substrate,
Light generated in the light emitting layer is extracted through the transparent substrate.

In the thin film EL panel having the above structure, a color filter is provided between the transparent substrate and the transparent electrode. However, the manufacturing process temperature of the thin film EL panel reaches about 500 ° C. in the light emitting layer manufacturing process and reaches about 300 ° C. in the insulating layer manufacturing process, and the heat treatment temperature of the transparent electrode is about 500 ° C.
It is not possible to employ an organic color filter having a lower heat resistance than an inorganic color filter as a color filter of the L panel in terms of heat resistance.

Therefore, in order to enable the use of the organic color filter, a thin film EL having a structure shown in FIG.
A panel has been proposed. The thin-film EL panel having the so-called inverted structure is formed by sequentially forming metal electrodes 6 on a substrate glass 61.
7, insulating layer 63, light emitting layer 64, insulating layer 65, transparent electrode 6
6, and on the other hand, an organic color filter 68 is laminated on a seal glass 69, and the seal glass 69 is arranged so as to face the transparent electrode 66 such that the organic color filter 68 faces the transparent electrode 66. .

The thin film EL panel having the inverted structure extracts light generated in the light emitting layer 64 to the side of the seal glass 69 opposite to the substrate glass 61. Therefore, as shown in FIG. 5, by disposing the organic color filter 68 above the transparent electrode 66, a color thin film EL panel can be realized.

That is, according to the thin film EL panel having the inverted structure, the organic color filter 68 is not affected by the manufacturing process temperature (about 500 ° C.) of the thin film EL panel. The color filter 68 can be employed without any problem in heat resistance.

[0008]

In the above-mentioned thin film EL panel having the inverted structure, a transparent electrode is laminated on a substrate glass, and a metal electrode (Al electrode) is provided on the opposite side of the substrate glass.
Is arranged, and unlike a normal thin-film EL panel having a non-inverting structure in which light is extracted from the substrate glass side, on the substrate glass 61,
A metal electrode 67 is laminated instead of a transparent electrode. This is because, in a thin film EL panel having an inverted structure, when a transparent electrode is also laminated on the substrate glass 61 which does not take out light, electric resistance is increased and power consumption is increased as compared with a normal thin film EL panel having a non-inverted structure. Because it increases.

As described above, the metal electrode 67 is laminated on the substrate glass 61. Since the metal electrode 67 is affected by the manufacturing process temperature of the EL panel, the metal electrode 67 has a melting point similar to that of the transparent electrode. High (700 ° C or higher) metal material
(For example, Mo, W, Ta, etc.).

However, the above-mentioned metal material having a high melting point (Mo,
W, Ta, etc.) have a higher specific resistance than the metal material Al of the metal electrode used in a normal thin-film EL panel, so that the thickness of the metal electrode 67 is set to be equal to the resistance of the electrode wiring. It must be thicker than a non-inverted thin film EL panel.

When the thickness of the metal electrode 67 is increased, the step at the side end of the metal electrode 67 increases,
The insulating layer 63 hardly adheres to the side surface of the metal electrode 67 (step coverage defect). For this reason, there is a problem that the durability against electrical insulation breakdown at the side end of the metal electrode 67 is reduced, and the disconnection of the electrode 67 and the breakdown of picture elements are easily caused.

An object of the present invention is to improve the dielectric breakdown durability of a thin-film EL panel having an inverted structure in which an inexpensive organic color filter having excellent workability can be employed.

[0013]

In order to achieve the above-mentioned object, the present invention provides a method for forming a second electrode by sequentially laminating a first electrode, a first insulating layer, a light emitting layer, a second insulating layer, and a second electrode on a substrate. In the thin-film EL panel having a heavy insulation structure, the first electrode is a metal electrode made of a high melting point metal having a melting point of 700 ° C. or more, and the bottom and side surfaces of the metal electrode are obtained by wet etching the metal electrode. Is characterized in that the angle between them is less than 90 °.

It is desirable that the angle between the bottom surface and the side surface of the metal electrode be 45 ° or less.

[0015]

Since the first electrode is made of a metal having a melting point of 700 ° C. or higher, the first electrode can withstand high temperatures during the manufacturing process of the thin-film EL panel.

Further, the metal electrode is wet-etched so that the angle between the bottom surface and the side surface of the metal electrode is 90 °.
As a result, the side surface of the metal electrode is inclined so that the metal electrode is tapered. That is, the projected area of the side surface of the metal electrode as viewed from the upper surface side is increased as compared with the conventional example in which the side surface of the metal electrode 67 shown in FIG. The layers are easy to adhere. Therefore, occurrence of dielectric breakdown at the side end of the metal electrode is suppressed, and dielectric breakdown durability is improved.

When the angle between the bottom surface and the side surface of the metal electrode is set to 45 ° or less, the dielectric breakdown durability at the side end of the metal electrode is smaller than the dielectric breakdown durability at the upper surface of the metal electrode. It is improved to about the same level, and the dielectric breakdown durability of the metal electrode is particularly improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

FIG. 1 shows a first embodiment of a thin film EL panel according to the present invention. This embodiment is a thin film EL panel having an inverted structure for realizing a color thin film EL panel.
A ZnS: Mn light-emitting layer 4 made of Mn-doped ZnS, a first insulating layer 3 and a second insulating layer 5 sandwiching the light-emitting layer 4;
A back electrode 2 as a first electrode and a translucent electrode 6 as a second electrode provided outside the insulating layers 3 and 5 are provided. Further, an organic color filter 8 is laminated on the seal glass 9, and the seal glass 9 is arranged so as to face the light transmitting electrode 6 so that the organic color filter 8 faces the light transmitting electrode 6.

The light emitting layer 4 is composed of a base material ZnS doped with Mn serving as a light emission center and having a thickness of about 1 μm and containing Mn added ZnS.
Consists of a membrane. The first insulating layer 3 has a thickness of 300 to
800Å of consist the Si ₃ N ₄ film 3b of the SiO ₂ film 3a and the thickness of 2,000-3,000Å. On the other hand, the second insulating layer 5
Si ₃ N ₄ film 5a having a thickness of 1000 to 2000 mm and a thickness of 300
And an Al ₂ O ₃ film 5b of about 500 °. The back electrode 2 as the first electrode is made of a metal Mo film, and the translucent electrode 6 as the second electrode is made of an ITO (tin-added indium oxide) film. As shown in FIG. 1, the angle between the bottom surface and the side surface of the back electrode 2, that is, the inclination angle θ of the electrode side surface is less than 90 °, and is tapered.

The steps of manufacturing the above-mentioned thin film EL panel will be described below.

First, a metal Mo film is sputter-deposited on a substrate glass 1, and the metal Mo film is processed into a predetermined stripe shape by photolithography and wet etching to form a striped back electrode 2. I do.

At the time of the wet etching, the metal Mo is used.
By wet-etching the film with a predetermined etching solution having a predetermined liquid temperature shown in Table 1 below, the back electrode 2 shown in FIG. 1 having a tapered side surface inclined can be formed. Angle θ between the bottom surface of the back electrode 2 and the side surface
(Tilt angle θ) depends on the type of the etching solution and the temperature of the etching solution as shown in Table 1 below. That is, the inclination angle θ of the side surface of the electrode 2 can be controlled by changing the etching conditions of the wet etching.

[Table 1]

Next, the resist formed on the electrode 2 is removed to complete the formation of the back electrode 2.

Next, the SiO ₂ film 3 is formed by a reactive sputtering method.
a and the Si ₃ N ₄ film 3 b are deposited to complete the formation of the first insulating layer 3. Next, after forming the light emitting layer 4 by an electron beam evaporation method or a CVD (chemical vapor deposition) method, a Si ₃ N ₄ film 5a and an Al ₂ O ₃ film 5b are deposited by a reactive sputtering method to form a _second layer. The formation of the insulating layer 5 is completed. Next, the second insulating layer 5
An ITO film is sputter-deposited thereon, and a stripe-shaped translucent electrode 6 orthogonal to the back electrode 2 is formed by photolithography.

Next, a filter material in which a green or red pigment is dispersed in a photosensitive resin is applied on the sealing glass 9 to form a filter film, and the filter film is formed using a photolithography method. Process into a mosaic. This process is repeated for the green and red filter films, respectively, to complete the formation of the organic color filter 8. Finally, the above organic color filter 8
The seal glass 9 is disposed so as to face the light-transmitting electrode 6 so that the light-transmitting electrode 6 and the light-transmitting electrode 6 face each other.
Oil is sealed between the seal glass 9 and the glass substrate 1.

According to the above-described manufacturing process, almost the same as the manufacturing process of the conventional thin-film EL panel shown in FIG.
The thin film EL panel of the present invention shown in FIG. 1 can be manufactured.

The thin-film EL panel of the above embodiment is shown in FIG.
As shown in (1), since the back electrode 2 as the first electrode is made of a metal Mo film having a melting point of 700 ° C. or more, the back electrode 2 withstands high temperatures during the manufacturing process of the thin film EL panel.

The back electrode 2 is wet-etched so that the angle between the bottom surface and the side surface of the back electrode 2 is 9 degrees.
Since the angle is less than 0 °, the side surface of the back electrode 2 is inclined so that the back electrode 2 is tapered. That is,
The projected area of the side surface of the back electrode 2 as viewed from above is increased as compared to the conventional example in which the side surface of the metal electrode 67 shown in FIG. The layer 3 becomes easy to adhere. Therefore, the back electrode 2
The occurrence of dielectric breakdown at the side end of the substrate is suppressed, and the dielectric breakdown durability is improved.

That is, according to the above embodiment, it is possible to provide a thin film EL panel which can adopt an organic color filter which is inexpensive and excellent in workability without lowering the dielectric breakdown durability.

As shown in Table 1, by selecting the type and temperature of the etching solution, the back electrode 2
If the inclination angle θ between the bottom surface and the side surface of
Unlike the case where the inclination angle θ exceeds 45 °, the concentration of the dielectric breakdown is concentrated on the side edge of the back electrode 2 (see FIG. 2B).
2A, most of the dielectric breakdown occurs on the upper surface of the back electrode 2 as shown in FIG. That is, if the inclination angle θ is set to 45 ° or less, the dielectric breakdown durability at the side end of the back electrode 2 can be improved to substantially the same as the dielectric breakdown durability of the upper surface of the back electrode 2.

Next, a second embodiment will be described. The structure of this embodiment is the same as that of the first embodiment shown in FIG. Only the method of manufacturing the back electrode as the first electrode in this embodiment is
Different from the first embodiment. Therefore, only the method of manufacturing the back electrode will be described.

First, as shown in FIG. 3A, a metal Mo film 4 serving as a back electrode as a first electrode is formed on a substrate glass 1.
After sputter-depositing 1, a photoresist 42 is applied, and the photoresist 42 is prebaked and exposed. Next, the photoresist 42 is immersed in chlorobenzene, and the surface of the photoresist 42 is insolubilized with an alkali solution to form an insolubilized layer 42A.
Next, as shown in FIG.
Is developed, post-baked and then etched.

As an etching solution used for the above-mentioned etching, an alkaline solution obtained by mixing NaOH and red blood salt is used. As shown in FIG. 3 (C), the alkali solution dissolves the metal Mo film 41 while gradually dissolving the non-insolubilized portion of the resist 42 from both sides toward the center. The depth of melting gradually decreases toward the center of 41, and the back electrode 2 having a side surface with a gentle gradient with respect to the upper surface of the substrate glass 1 can be formed. Finally, as shown in FIG. 3D, the resist 42 is peeled off, and the formation of the back electrode 2 is completed. According to the above method,
The angle between the bottom surface and the side surface of the back electrode 2 can be set to 45 ° or less. When the inclination angle θ is set to 45 ° or less, unlike the case where the inclination angle θ exceeds 45 °, the concentration of the dielectric breakdown on the side end of the back electrode 2 is increased (see FIG. 2B). As shown in FIG. 2A, most of the dielectric breakdown occurs on the upper surface of the back electrode 2. Therefore, the dielectric breakdown durability of the side electrode of the back electrode 2 can be improved to substantially the same level as the dielectric breakdown durability of the upper surface of the back electrode 2.

Next, a third embodiment is shown in FIG. This embodiment differs from FIG. 1 only in that a corrosion-resistant inorganic thin film 10 made of Si ₃ N ₄ is formed between the substrate glass 1 and the back electrode 52 and that the back electrode 52 is made of a metal W (tungsten) film.
Is different from the first embodiment shown in FIG. Therefore, only the portion related to the inorganic thin film 10 and the back electrode 52 will be described.

[0036] The corrosion-resistant inorganic thin film 10 is formed by depositing a Si ₃ N ₄ having a thickness of 2000Å by a reactive sputtering method on the substrate glass 1. Next, a metal W film is sputter-deposited on the inorganic thin film 10 to a thickness of 1500 °, and the metal W film is processed into a predetermined stripe shape by photolithography and wet etching to form a stripe-shaped rear surface. An electrode 52 is formed. By performing wet etching of the metal W film using an etching solution in which hydrofluoric acid and nitric acid are mixed at a ratio of 1: 5 at the time of the wet etching, the back electrode 52 shown in FIG. Can be formed.

Since the corrosion-resistant inorganic thin film 10 made of Si ₃ N ₄ is formed on the substrate glass 1, the substrate glass 1 is not corroded by the hydrofluoric acid contained in the etching solution during the wet etching. That is, even if an etchant containing hydrofluoric acid is used during the wet etching, there is no fear that the substrate glass 1 is corroded, and the valley between the back electrodes 52, 52 becomes deep due to the corrosion of the substrate glass 1. Can be prevented. Accordingly, it is possible to prevent a decrease in the adhesion of the insulating film 3 at the valleys, and to prevent the thickness of the insulating film 3 from being reduced at the valleys, thereby preventing a decrease in dielectric breakdown durability.

[0038]

As is apparent from the above description, the present invention provides a double insulating structure in which a first electrode, a first insulating layer, a light emitting layer, a second insulating layer, and a second electrode are sequentially laminated on a substrate. Structured thin film E
In the L panel, since the first electrode is a metal electrode made of a high melting point metal having a melting point of 700 ° C. or more, the first electrode withstands high temperatures during the manufacturing process of the thin film EL panel.

Further, since the angle between the bottom surface and the side surface of the metal electrode is set to less than 90 ° by wet etching the metal electrode, the side surface of the metal electrode is
The metal electrode is inclined so as to be tapered. That is, the projected area of the side surface of the metal electrode as viewed from the upper surface side is:
In comparison with the conventional example in which the side surface of the metal electrode 67 shown in FIG. 5 is not inclined, the number increases, and the first insulating layer easily adheres to the side surface of the metal electrode. Therefore, occurrence of dielectric breakdown at the side end of the metal electrode can be suppressed, and dielectric breakdown durability can be improved.

When the angle between the bottom surface and the side surface of the metal electrode is set to 45 ° or less, the dielectric breakdown durability at the side end of the metal electrode is made equal to the dielectric breakdown durability at the top surface of the metal electrode. It can be improved to approximately the same level, and the dielectric breakdown durability of the metal electrode can be particularly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of a thin film EL panel according to the present invention.

FIG. 2 is a schematic diagram showing a dielectric breakdown point in the embodiment.

FIG. 3 is a cross-sectional view illustrating a manufacturing process of a back electrode according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a third embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional thin-film EL panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate glass 2,52 Back electrode 3 First insulating layer 4 Light emitting layer 5 Second insulating layer 6 Translucent electrode 8 Organic color filter 9 Seal glass 10 Corrosion-resistant inorganic thin film

Claims (2)

(57) [Claims] 1. A thin film EL panel having a double insulating structure in which a first electrode, a first insulating layer, a light emitting layer, a second insulating layer, and a second electrode are sequentially stacked on a substrate, wherein the first electrode is The metal electrode is made of a high melting point metal having a melting point of 700 ° C. or more, and the angle between the bottom surface and the side surface of the metal electrode is less than 90 ° by wet etching the metal electrode. Thin film EL panel. 2. The thin film EL panel according to claim 1, wherein the angle between the bottom surface and the side surface of the metal electrode is 45 ° or less.