JPH05217673A - Manufacture of thin film el element - Google Patents

Abstract

PURPOSE:To supplement oxygen deficiency and prevent damage to the surface of a thin film EL element by purifying the substrate surface of a specified layer formed by sputtering with oxygen plasma ashing in a chamber. CONSTITUTION:A transparent electrode 2 is laid on a glass substrate 1, and before forming an oxide film 3a and the first insulation layer 3, the board surface as substratum is subjected to oxygen plasma ashing in the condition being set in a chamber. Then sputtering is made in the same chamber to form oxide film 3a, and upon purifying the surface of the oxide film 3a, the first insulation layer 3 is formed by sputtering. After formation of this first insulation layer 3, the surface of the first insulation layer 3 is subjected to oxygen plasma ashing, and then a buffer layer 4a, light emission layer 4, and another buffer layer 4b are formed in lamination. Another oxygen plasma ashing is made after formation of the layers 4, 4a, 4b and before formation of the second insulation layer 5. Then formation of the second insulation layer 5 is conducted in the same chamber continuously with the situation kept as it is.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film EL device, and more particularly to a method for cleaning each layer of the device.

[0002]

2. Description of the Related Art An example of the structure of a thin film EL element in a thin film EL matrix type display panel is shown below with reference to FIGS. The left half of FIG. 2 is a cross-sectional view in the X direction, and the right half is a cross-sectional view in the Y direction orthogonal to the X direction. In the figure, (1) is a transparent insulating substrate, (2) is a transparent electrode,
(3) is a first insulating layer, (4) is a light emitting layer, (5) is a second insulating layer, and (6) is a back electrode. The translucent insulating substrate (1) is a glass substrate. The transparent electrode (2) is formed by forming ITO (In ₂ O ₃ + SnO ₂ ) or the like on the glass substrate (1) by vapor deposition in a large number of stripes at a constant pitch in the X direction. The first insulating layer (3) is formed on the transparent electrode (1) and the glass substrate (1) by tantalum oxide (Ta ₂ O ₅ ), alumina (Al ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), or nitriding. It is a transparent film formed by sputtering to a thickness of 0.3 to 0.5 μm. The light emitting layer (4) is formed by forming a phosphor of ZnS: Mn on the first insulating layer (3) to a thickness of 0.5 to 1.0 μm by an electron beam evaporation method or the like. The second insulating layer (5) is a transparent film formed by depositing alumina (Al ₂ O ₃ ) or yttrium oxide (Y ₂ O ₃ ) or nitride on the entire surface of the light emitting layer (4) by vapor deposition or sputtering. is there. The back electrode (6) is an aluminum vapor deposition film formed on the second insulating layer (5) in a large number of stripes at a constant pitch in the Y direction.
Although not shown, a concave plate-shaped cover glass (8) is fixed on the glass substrate (1) via an adhesive so as to surround the thin film EL element (7), and thus the thin film EL element is attached.
A matrix type display is formed, and further, in an envelope composed of the glass substrate (1) and the cover glass (8),
An insulating protective fluid such as silicon oil is enclosed in order to improve the moisture resistance of the thin film EL element (7).

In the thin film EL matrix type display, as shown in FIG. 3, a transparent electrode (2) and a back electrode (6) of a thin film EL element (7) intersect in a matrix to form a large number of matrix pixels ( m). In addition, the respective terminal portions (2a) (6) of the transparent electrode (2) and the back electrode (6)
Every other a) is extended to the opposite peripheral portion on the glass substrate (1), and although not shown, an external extraction pad is appropriately provided thereon. Therefore, both electrodes (2)
When a drive voltage is selectively applied between the terminal portions (2a) and (6a) of (6), the pixel portion of the light emitting layer (4) selectively emits light to perform dot matrix display of desired information.

In the manufacture of the thin film EL element (7),
Transparent electrode (2), first insulating layer on glass substrate (1)
(3), light emitting layer (4), second insulating layer (5) and back electrode
When laminating (6), dust, dust, etc. are attached between the layers.
When worn, there are pinholes in the layers formed on top of it.
It causes to occur. Then, 1.5 × 1 for each layer
0 ⁶A relatively high electric field of about V / cm is applied.
Therefore, dielectric breakdown is likely to occur, and the location of the dielectric breakdown
Not only that, the stripes themselves at that location also become defective.
Therefore, conventionally, it was carried out to the outside of the chamber just before forming each layer.
After performing the wet cleaning of the element surface,
The first insulating layer (3) and the second insulating layer.
Since (5) uses sputtering, the chamber
Element substrate by sputter etching with it set inside
The surface is irradiated with argon ions for cleaning.
Furthermore, when carrying out the thin film EL element (7) to the outside of the chamber
While introducing slow gas, when carrying it into the chamber
Slow exhaust is used to prevent dust from rising.

[0005]

The problem to be solved by the invention is that when the cleaning treatment is carried out by sputter etching, particularly when the underlying surface to be cleaned is the light emitting layer, the surface is damaged by spattering and the surface is roughened. This is the point that when a microcrack is generated or an insulating layer made of an oxide is a base, oxygen deficiency occurs and the withstand voltage characteristic is deteriorated.

[0006]

According to the present invention, a transparent electrode, a first insulating layer, a light emitting layer, and a second insulating layer are sequentially laminated on a transparent insulating substrate to form a thin film EL element. Characterized in that the underlayer surface of a predetermined layer formed by sputtering is cleaned by oxygen plasma ashing in the chamber, and

The first insulating layer is formed of oxide, and
It is characterized in that a buffer layer made of an oxide film, which is a base of oxygen plasma ashing, is provided on the surface of the light emitting layer on the side of the second insulating layer.

[0008]

According to the above technical means, when the transparent electrode, the first insulating layer, the light emitting layer, and the second insulating layer are sequentially laminated on the translucent insulating substrate to form a thin film EL element, sputtering is performed. The underlying surfaces of the first and second insulating layers formed in step 1 are cleaned by oxygen plasma ashing in the chamber to remove organic deposits such as dust and dust. In particular, when a buffer layer made of an oxide film which is a base of oxygen plasma ashing is provided on the second insulating layer side of the first insulating layer and the light emitting layer, oxygen vacancies can be replenished.

[0009]

An embodiment of the present invention will be described below with reference to FIG.
To do. The same parts as those shown in FIG. 2 are designated by the same reference numerals.
And its description is omitted. The first insulating layer (3) is transparent
An oxide film (SiO 2) that is familiar to the electrode (2)₂) (3a)
Is laminated through , The second insulating layer (5) as well
On the back electrode (6) side, an oxide film (SiO 2₂) (5a) Stacking
It is formed. Further, the light emitting layer (4) is symmetrically arranged from above and below.
0 Å thick oxide film (Y₂O₃)
The structure is such that it is sandwiched between the fur layers (4a) and (4b) for protection.
It

The operation of the present invention (method of the present invention) will be described below based on the above configuration. The feature is that oxygen plasma ashing is used instead of the conventional sputter etching as a means for cleaning the underlying surface before forming the first and second insulating layers (3) and (5). That is, the glass substrate (1)
After stacking the transparent electrode (2) made of ITO on the top,
Before the oxide film (3a) and the first insulating layer (3) are formed by sputtering, the pressure is 2 × 10 ^{−3 to} 5 × 10 ⁻² T with the substrate surface as a base set in the chamber.
Pretreatment is performed by oxygen plasma ashing at orr, power of 0.56 to 2.22 W / cm ² , and frequency (13.56 MHz). Then, the high temperature plasma compulsorily combusts and removes the organic substances which are the main components such as dust and dust on the substrate surface, and the substrate surface is cleaned. Thereafter, sputtering is performed in the same chamber as it is to form an oxide film (3a), and the surface thereof is continuously cleaned by oxygen plasma ashing as described above. (3) is formed.

Next, after the first insulating layer (3) is formed, the surface of the first insulating layer (3) as an underlayer is pretreated by oxygen plasma ashing in a state where it is set in the chamber in the same manner, and then the buffer is formed. The layer (4a), the light emitting layer (4) and the buffer layer (4b) are laminated by electron beam evaporation. Further, after the light emitting layer (4) and its buffer layers (4a) and (4b) are formed and before the formation of the second insulating layer (5), oxygen plasma ashing is performed for pretreatment. Then, each of the high temperature plasma removes the organic dust and the like to clean the underlying surface, and the underlying first insulating layer (3) and the buffer layer (4b) are oxide layers.
Further, it is hardly overoxidized, and oxygen vacancies are replenished to prevent damage to the underlying surface. After that, similarly to the above, the second insulating layer (5) may be continuously formed in the same chamber by sputtering.

The first and second insulating layers (3) and (5) may have a single layer structure of oxide.

[0013]

According to the present invention, when manufacturing a thin film EL device, the underlying surface of a predetermined layer formed by sputtering is cleaned by oxygen plasma ashing in a chamber, so that organic dust and dirt are produced. When an oxide layer is provided as a base while removing the above, oxygen vacancies are supplemented to prevent surface damage.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part of an element showing an embodiment of a method of manufacturing a thin film EL element according to the present invention.

FIG. 2 is a side sectional view showing an example of a conventional thin film EL element.

FIG. 3 is a partial plan view showing an example of a conventional thin film EL element.

[Explanation of symbols]

 1 translucent substrate 2 transparent electrode 3 first insulating layer 4 light emitting layer 5 second insulating layer 6 back electrode

Claims (2)

[Claims] 1. A predetermined layer formed by sputtering when a transparent electrode, a first insulating layer, a light emitting layer, and a second insulating layer are sequentially laminated on a translucent insulating substrate to form a thin film EL element. 2. A method of manufacturing a thin film EL element, characterized in that the underlayer surface is cleaned by oxygen plasma ashing in a chamber. 2. The first insulating layer is formed of an oxide, and a buffer layer made of an oxide film serving as a base of oxygen plasma ashing is provided on the surface of the light emitting layer on the side of the second insulating layer. 1. The method for manufacturing a thin film EL element according to 1.