JP2509354B2 - Method for manufacturing thin film EL panel - Google Patents

Description

The present invention relates to a method for manufacturing a thin film EL panel having a so-called three-layer structure in which insulating layers are provided above and below a light emitting layer.

<Prior Art> Conventionally, as a method of manufacturing a thin film EL panel of this type, for example, there is a method shown in FIGS. 4 (a) to 4 (c). That is, a transparent conductive film made of ITO (indium tin oxide) is formed on the surface of the glass substrate 11 and photo-etched to form parallel strip-shaped transparent electrodes 12 (FIG. 4 (a)). Next, as shown in FIG.
Is attached to the substrate holder 20 with the surface facing downward, and the peripheral region where no film is formed is covered with the frame-shaped mask 21. And
With the substrate 11 being heated so that the adhesion strength of the film to be formed is increased, as shown in FIG. 4 (b), a lower insulating layer having a Si ₃ N ₄ film is formed by an electron beam evaporation method or a sputtering method. A light emitting layer 14 made of ZnS: Mn and an upper insulating layer 15 having a Si ₃ N ₄ film are formed. Finally, a metal film is formed by an electron beam evaporation method and photoetched to form a strip-shaped back electrode 17 and a terminal electrode 18 (FIG. 4 (c)).

<Problems to be Solved by the Invention> By the way, the mask 21 and the substrate holder 20 are
It has a larger heat capacity than 11, and is attached to the chamber wall surface by a supporting member. for that reason,
When the substrate 11 is heated, heat is radiated to the chamber wall surface due to heat conduction, and a temperature distribution is generated such that the peripheral region of the substrate 11 is lower in temperature than the central region as shown in FIG. 3B. Since the film growth rate is high in the region where the substrate temperature is low, the lower insulating layer is maintained in this state as in the conventional manufacturing method described above.
13, when the light emitting layer 14 and the upper insulating layer 15 are formed, the thickness of these three layers is large in the peripheral region of the film forming region E ₀ , that is, in the vicinity of the mask 21, as shown in FIG. 3C. , The distribution becomes thin near the center. This distribution is particularly remarkable in the ZnS: Mn light emitting layer 14 in which the film attachment coefficient largely changes depending on the substrate temperature. Since the film thickness and the emission luminance have a substantially proportional relationship, when the film thickness has the above distribution, the emission luminance is the film formation region E _0, that is, the display of the panel, as shown in FIG. 3 (d). In the area D ₀ , a pan-bottomed distribution is shown, and a brightness difference B ₀ occurs. Thus, the EL manufactured by the conventional manufacturing method
The panel had a problem in terms of light emission characteristics.

Further, the above-mentioned conventional method has a problem that the substrate is contaminated by the insulating film or the light emitting layer film attached to the mask 21.
Substrate contamination causes defects in thin film EL panels.

Therefore, an object of the present invention is to have uniform emission characteristics,
It is an object of the present invention to provide a method for manufacturing a thin film EL panel with few defects.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a thin film EL formed by sequentially laminating a transparent electrode, a lower insulating layer, a light emitting layer, an upper insulating layer and a back electrode on a glass substrate. In the method of manufacturing a panel, a lower insulating layer, a light emitting layer, and an upper insulating layer are formed on almost the entire surface of the substrate, and then an organic film is formed on the upper insulating layer. Lower insulating layer,
The light emitting layer, the upper insulating layer, and the organic film are removed by a mechanical grinding method to expose the end portion of the transparent electrode, and then the organic film remaining on the upper insulating layer is removed.

It is desirable that the organic film is formed of a material that can be easily removed by a solvent and does not leave stains on the upper insulating layer.

<Operation> When a light emitting layer is formed on almost the entire surface of a substrate, a mask is not used when performing vapor deposition or sputtering. Therefore, there is a problem that the substrate is contaminated by a film piece of an insulating layer or a light emitting layer attached to a conventional mask. In addition, the difference in temperature between the peripheral region and the center of the substrate during the heating of the substrate becomes smaller than that when a mask is used. Therefore, the formed film has the same tendency of being thick in the peripheral portion of the film forming region and thin in the vicinity of the center, but the variation in the film thickness is reduced.

Further, since the peripheral portion of the film formation region where the film thickness varies greatly is removed, as a result, the spread of the emission luminance distribution becomes extremely small, and uniform emission characteristics can be obtained.

Further, during the grinding process using the mechanical method, the organic film covers the upper insulating layer, so that the abrasive, the ground three-layer film, and the fine particles of the substrate glass adhere to the organic film. Then, the fine particles attached to the organic film are removed together with the organic film in the step of removing the organic film. As described above, since the organic film prevents contamination on the upper insulating layer that may occur when the upper insulating layer is directly covered with a mask and is ground, the rear electrode to be formed on the upper insulating layer. Since it is difficult to form pinholes, the adhesiveness with the upper insulating layer is good, and the electric field is uniformly applied, it is possible to manufacture a thin film EL panel having uniform emission characteristics and few defects.

<Examples> Hereinafter, the present invention will be described in detail with reference to illustrated examples.

FIG. 1 is a process chart showing a method of manufacturing a thin film EL panel which is an embodiment of the present invention. Hereinafter, description will be made with reference to FIG.

First, as shown in FIG. 1 (a), a transparent conductive film made of ITO and having a film thickness of 1000 to 2000Å is formed on the surface of a glass substrate 1 such as aluminosilicate glass, and parallel strip-shaped transparent electrodes are formed by photoetching. Form 2.

Next, as shown in FIG. 2 (a), the substrate 1 is attached to the substrate holder 20 with the surface thereof facing downward, and the mask 21
Without attaching, the substrate 1 is heated to a predetermined temperature as it is. In this state, the lower insulating layer 3 made of SiO ₂ , Si ₃ N ₄ or the like is spread over substantially the entire surface of the substrate 1 including the transparent electrode 2 by a method such as a sputtering method or an electron beam evaporation method.
Form to a thickness of Å. Then, using a similar method, Zn
Light-emitting layer 4 consisting of S: Mn with a thickness of ~ 8000Å and Si ₃ N ₄ or Al ₂
An upper insulating layer 5 made of O ₃ or the like and having a film thickness of up to 2000 Å is formed over the substantially entire surface of the substrate 1. Further, a positive type photoresist (hereinafter referred to as a positive resist) having a thickness of 1 to 3 is formed on the entire surface of the upper insulating layer 5 by using a spinner or a roll coater.
By applying μ, the positive resist film 6 as an example of the organic film is formed. (FIG. 1 (b)).

Next, as shown in FIG. 1C, a mask 31 protects the three-layered films 3, 4, 5 and the positive resist film 6 which are formed as a multi-layered film and serves as a display area D _{1 of the} panel. Then, unnecessary portions of the peripheral area Δ are completely removed by a method of spraying an abrasive with a high pressure such as a dry blast method or a liquid honing method. During the film removing process in the peripheral area Δ, fine particles such as an abrasive or a ground film are removed from the mask 31 and the positive resist film 6.
However, due to the protection by the positive resist film 6, adhesion of fine particles to the upper insulating layer 5 is prevented. When the film removal is completed, the end 2a of the transparent electrode 2 is
As shown in FIG. 1D, the three-layer films 3, 4, 5 and the positive resist film 6 are exposed. Fig. 1 (d)
Shows the state after the mask 31 is removed. Since the positive resist film 6 covers the upper insulating layer 5 even when the mask 31 is removed, the upper insulating layer is covered by the particles in the peripheral region of the substrate. 5 is never contaminated.

After removing the mask 31, the positive resist film 6 is removed with a solvent such as acetone or an alkaline aqueous solution such as NaOH. At this time, the fine particles adhering to the positive resist film 6 are also removed at the same time.

When using the liquid honing method to remove the above three-layer film, use # 400 to # 100 with Alundum (trade name) or the like.
By using a hard abrasive of about 0 and relatively fine particles, it is possible to easily and completely remove it in about 20 seconds per side.

Finally, as shown in FIG. 1 (e), a laminated metal film made of Al and Ni is formed by an electron beam evaporation method and photoetched to form a strip-shaped back electrode 7 and a terminal electrode 8. At this time, the terminal electrode 8 is in a state of being electrically connected to the end portion 2a of the transparent electrode 2 exposed from the three-layer film 3, 4, 5.

As described above, the unnecessary portions of the three-layer films 3, 4, 5 formed on the substantially entire surface of the substrate 1 are removed by a relatively simple method to remove the three-layer film 3,
It is possible to form the terminal electrode 8 that conducts to the end portion 2a of the transparent electrode 2 exposed from 4 and 5. Also, like this, thin film EL
At the time of manufacturing the panel, in the above process, the substrate 1 is heated as it is without attaching the mask 21, and therefore, as shown in FIG. The temperature difference in the plane is small. Therefore, in this state, when the three-layer film is formed on substantially the entire surface of the substrate 1, the film thickness tends to be thick around the film formation region E ₁ and thin near the center as shown in FIG. 2 (c). Is still the same,
Variations in film thickness are reduced. Furthermore, in the above process,
Since the three-layer film in the peripheral area Δ other than the predetermined display area D ₁ is removed, the luminance difference becomes smaller (luminance difference B ₁ ) as shown in FIG. 2 (d). Therefore, the display quality of the thin film EL panel can be improved. Further, in the above process, since the positive resist film 6 is applied and formed on the upper insulating layer 5, it is possible to prevent the upper insulating layer 5 from being contaminated by fine particles such as an abrasive during the grinding process or the removal of the mask 31. Can be prevented. Moreover, there is an advantage that the positive resist film 6 can be easily removed by a solvent.

In this embodiment, the liquid honing method and the dry blast method are used as the film removing method, but the method is not limited to this, and other mechanical or physical methods may be used. Further, the materials of the lower insulating layer, the upper insulating layer, and the light emitting layer are not limited to those of this embodiment. In addition, in this embodiment, the organic film 6 is formed by using a positive type photoresist.
However, another material may be used as long as it is easy to remove and does not leave stains on the upper insulating layer 5. However,
Rubber-based materials such as silicone rubber are not suitable for use because they interfere with mechanical grinding.

<Effect> As is apparent from the above, according to the present invention, the substrate is heated without using a mask to form a film on substantially the entire surface of the substrate, and after the film is formed, the film thickness is relatively large. Since the peripheral portion of the formation region is removed and only the region where the film thickness variation is extremely small is used, it is possible to suppress the luminance difference to be extremely small and improve the light emission characteristics of the thin film EL panel.

Further, since no mask is used when forming the film, the shape of the substrate holder is simplified, the weight and weight of the substrate holder can be made common, and the production efficiency is improved.

Further, in the case of performing so-called multi-cavity production for producing a plurality of EL panels from a single glass substrate, it is possible to form a film without using a complicated mask having a plurality of openings. By applying the present invention, that is, by forming a film on the entire surface of the substrate, removing the film of the portion used as the terminal portion, and establishing electrical continuity between the exposed end portion of the transparent electrode and the terminal electrode, it can be easily performed. .

Further, according to the present invention, since the organic film is formed on the upper insulating layer to protect the upper insulating layer before removing the film in the peripheral region of the substrate, it is used in the mechanical grinding process. It is possible to prevent the abrasive or the fine particles of the ground film or substrate from directly adhering to the upper insulating layer and contaminating the upper insulating layer. Fine particles adhering to the organic film can be removed from above the thin film by removing the organic film before providing the terminal electrode that conducts to the end of the transparent electrode, so that the adhesion to the upper insulating layer is improved. The back electrode can be formed well without causing pinholes, the application of the electric field is uniform, and a thin film EL panel having uniform emission characteristics and few defects can be manufactured.

[Brief description of drawings]

FIGS. 1 (a) to 1 (e) are process diagrams showing a method for manufacturing a thin film EL panel according to an embodiment of the present invention, and FIG. 2 (a) shows a substrate mounting state when forming a three-layer film in the present invention. 2B shows the temperature distribution of the substrate, FIG.
FIG. 3 (c) is a diagram showing the thickness distribution of the above three-layer film, FIG. 2 (d) is a diagram showing the emission luminance distribution of the thin film EL panel manufactured according to the present invention, and FIG. 3 (a) is a conventional diagram. The figure which shows the board | substrate attachment state at the time of forming a three-layer film in a manufacturing method, FIG.3 (b) is a figure which shows the temperature distribution of the said board | substrate, FIG.3 (c) is a figure which shows the film thickness distribution of the said three-layer film. FIG. 3 (d) is a diagram showing the distribution of the emission luminance of a thin film EL panel manufactured by the above conventional manufacturing method, and FIGS. 4 (a) to 4 (c) are conventional thin film EL panels.
It is a figure which shows the process of the manufacturing method of a panel. 1,11 …… Glass substrate, 7,17 …… Back electrode, 2,12 …… Transparent electrode, 8,18 …… Terminal electrode, 3,13 …… Lower insulating layer, 20 …… Substrate holder, 4,14 ...... Light emitting layer, 21,31 …… Mask, 5,15 …… Upper insulating layer, 32 …… Abrasive agent, 6 …… Positive resist film, 33 …… Abrasive agent spray gun.

Front page continued (72) Inventor Hiroshi Kishishita 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka, Japan Inside Sharp Corporation (72) Inventor Hisakami Uede, 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Prefecture

Claims (1)

(57) [Claims] 1. A method for manufacturing a thin film EL panel, which comprises sequentially forming a transparent electrode, a lower insulating layer, a light emitting layer, an upper insulating layer and a back electrode on a glass substrate, wherein the lower insulating layer is formed on substantially the entire surface of the substrate. A light emitting layer and an upper insulating layer are formed, and then an organic film is formed on the upper insulating layer, and then the lower insulating layer and the light emitting layer in the peripheral region are formed.
Manufacturing of a thin film EL panel characterized by removing the upper insulating layer and the organic film by a mechanical grinding method to expose the end of the transparent electrode, and then removing the organic film remaining on the upper insulating layer. Method.