JPH0580796B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a method for manufacturing a thin film EL panel,
It is especially used when forming the light emitting layer of a matrix type thin film EL panel.

Conventional technology Conventionally, for AC-operated thin-film EL devices, a high electric field (about 10 ⁸ V/cm) is regularly applied to the light emitting layer, and in order to improve dielectric strength, luminous efficiency, stability of operation, etc. ~1.0wt% Mn (or Cu,
A three-layer structure ZnS:Mn (or ZnSe:Mn) EL device has been developed in which a light-emitting layer of ZnS, ZnSe, etc. doped with Al, _Br , etc.) is sandwiched with a dielectric thin film of Y ₂ O 3, Ta ₂ O ₅ , etc. It has been confirmed that various light emitting characteristics have been improved. This thin film EL element emits high-intensity light when an alternating current electric field of several KHz is applied, and has a long lifespan.

FIG. 2 shows the basic structure of a ZnS:Mn thin film EL device as an example of a thin film EL device.

To specifically explain the structure of a thin film EL element based on Fig. 2, the hard and transparent front glass substrate 1
A transparent electrode 2 made of In ₂ O ₃ , SnO ₃ , etc. is placed on top, and a first layer made of Y ₂ O ₃ , Ta ₂ O ₅ , Al ₂ O ₃ , Si ₃ N ₄ , SiO _{2 ,} etc. is laminated thereon. The dielectric layer 3 is formed by sputtering, electron beam evaporation, or the like. On the first dielectric layer 3 is a ZnS luminescent layer 4 obtained by electron beam evaporation of ZnS:Mn sintered pellets.
is formed. At this time, the ZnS:Mn sintered pellets used for deposition are pellets in which the concentration of Mn, which is an active substance, is set to suit the purpose. ZnS
A second dielectric layer 5 made of a material similar to or different from that of the first dielectric layer 3 is laminated on the light emitting layer 4,
Furthermore, a back electrode 6 made of Al or the like is formed by vapor deposition thereon. The transparent electrode 2 and the back electrode 6 are formed into a stripe shape as shown in FIG. 3, and a matrix electrode structure is adopted in which a plurality of electrodes are arranged perpendicularly to each other. Crossing position 7 (hatched area shown)
corresponds to one pixel on the panel. The transparent electrode 2 and the back electrode 6 are connected to an AC power source 10 via switches 8 and 9, respectively, to drive the thin film EL element.

In the above configuration, when the switches 8 and 9 are closed and an AC voltage is applied between the electrodes 2 and 6, the light emitting layer 4
The AC voltage is induced between the dielectric layers 2 and 5 on both sides of the light emitting layer 4, and the electric field generated in the light emitting layer 4 excites the conductor and accelerates it to obtain sufficient energy. The electrons directly excite the Mn luminescent center, and when the excited Mn luminescent center returns to its ground state, it emits orange-yellow light. That is,
Electrons accelerated by a high electric field excite the electrons of the Mn atoms that enter the Zn site, which is the luminescent center in the luminescent layer 4, and when they fall to the ground state, they emit strong light in a wide wavelength range with a peak at approximately 5850 Å. .

The thin film EL element having the above structure can be used as a flat thin display device that takes advantage of the space factor to display characters, symbols, still images, and moving images in computer output display terminal equipment and various other display devices that contain characters and figures. It is very effective and can be used as a display means.

However, the dielectric layer of a thin-film EL element contains many pinholes and microcracks generated during the manufacturing process, and moisture, etc. enters the light-emitting layer 4 through these defects, causing heat generation due to EL emission loss and interlayer This may lead to peeling, deterioration of device characteristics, etc.

In order to solve the above problem, as shown in Fig. 4, we have developed an enlargement of the microscopic thermal damage area that occurs due to breakdown caused by imperfections peculiar to thin film EL elements, such as pinholes, when electricity is applied. A thin film EL panel 11 is known that prevents and immobilizes the air, provides moisture protection in an atmospheric environment, has a heat dissipation effect, and is also effective against vibration and deflection.

This thin film EL panel 11 will be explained based on FIG. 4. The left half of FIG. 4 shows a cross-sectional view in the X direction parallel to the transparent electrode 2, and the right half shows a cross-sectional view of the transparent electrode 2.
A cross-sectional view in the Y direction perpendicular to is shown. Reference numeral 1 denotes a glass substrate, on which transparent electrodes 2 are arranged parallel to each other in a band shape at a constant pitch interval, and on top of which a first dielectric layer 3, a light emitting layer 4, and a second dielectric layer are arranged. 5. Thin film EL element 12 with laminated back electrode 6
is configured. A dish-shaped cover glass 13 is placed on the glass substrate 1 so as to house this thin film EL element 12.
A thin film EL element 12 is superimposed on the top and in the internal gap.
is built-in. Glass substrate 1 and cover glass 13
The joints are sealed with an adhesive 14 such as epoxy resin or photocurable resin (photopond). That is, the glass substrate 1 and the cover glass 13 are thin film EL.
An envelope 15 for the element 12 is constructed. A thin film EL element 12 is built in the envelope 15, and a thin film of silicone oil, vacuum grease, etc.
An insulating protective fluid 16 for protecting the EL element 12 is filled and sealed (Japanese Unexamined Patent Publication No. 122990/1983).

In the thin film EL panel 1, the first dielectric layer 3, the light emitting layer 4, and the second dielectric layer 5 are all formed by attaching a metal mask 19 to the glass substrate 1, as shown in FIG. A predetermined substance 22 is evaporated from an evaporation source 21 with an electron beam 23 while the base of the glass substrate 1 is heated with a halogen lamp 20.

Problems to be Solved by the Invention However, when the metal mask 19 is used as described above and a film is formed by heating the base of the glass substrate 1 with the halogen lamp 20 and depositing it, the metal mask 19
A temperature difference occurs between the center and the periphery of the glass substrate 1 due to thermal conduction, heat capacity, etc., which affects the crystallinity and film quality of the light-emitting layer 4 and causes uneven brightness between the center and the periphery. ing. In addition, glass substrate 1
When the base is heated, the area around the opening of the metal mask deforms as shown in the figure, and the adhesion with the glass substrate 1 deteriorates, so the metal mask 19 and the glass substrate 1
As a result, as shown in FIG. 6, the vapor-deposited material wraps around the gap between the two, resulting in an extremely thin part at the periphery, where peeling is likely to occur. For this reason,
If the back electrode 6 crosses this portion, it may cause the back electrode 6 to break.

Means for Solving the Problems Therefore, in the present invention, the first dielectric layer 3 is formed by sputtering a dielectric material such as Al ₂ O ₃ , Si ₃ N ₄ , Ta ₂ O ₅ or the like using a metal mask. A light emitting layer such as ZnS:Mn is formed on the first dielectric layer by vapor deposition or the like without using a metal mask, and then patterned by known photolithography or the like.

Effect: According to the above method, the first dielectric layer is formed by sputtering with strong adhesion to the glass substrate, so peeling of extremely thin parts that occur around the periphery does not occur, and the mask Since the light emitting layer that has been formed on the entire surface is patterned without using a light emitting layer, it is possible to form a light emitting layer that has uniform crystallinity and thickness throughout the entire surface, and therefore has a clear border around the periphery. A thin film EL panel with no unevenness can be obtained.

Embodiment Hereinafter, a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1A to 1D show cross-sectional views at each stage of film formation of the first dielectric layer 3 and the light emitting layer 4. first,
After forming a large number of striped transparent electrodes 2 parallel to the X direction on a glass substrate 1 by a known method, a metal mask 19 is attached on top of the transparent electrodes 2, and Al ₂ O having excellent acid resistance is formed. A first dielectric layer ₃ having a thickness of about 3000 Å is formed by sputtering a dielectric material such as 3, Si ₃ N ₄ or Ta ₂ O ₅ (FIG. 1A).

Next, the metal mask 19 is removed and a phosphor such as ZnS:Mn is deposited on the first dielectric layer 3 and the transparent electrode 2 to form a light emitting layer 4 with a thickness of about 6000 to 8000 Å. (Figure 1B).

Next, a photoresist film 2 is formed on the entire surface of the light emitting layer 4.
4 is formed, and the photoresist film 24 is patterned into a predetermined shape through known exposure and development steps (FIG. 1C).

When the whole is immersed in an etching solution such as cold hydrochloric acid in the above state, the light-emitting layer 4 that is not covered with the photoresist film 24 is etched, and a light-emitting layer 4 with a pattern corresponding to the pattern of the photoresist film 24 is formed. Ru. Thereafter, when the photoresist film 24 is dissolved and removed with an organic solvent, the light emitting layer 4 with clearly defined boundaries of a predetermined shape is exposed (FIG. 1D).

In the above embodiment, the light emitting layer 4 is patterned by wet etching using cold hydrochloric acid, but it may also be patterned by dry etching such as reactive ion etching (RIE).

Effects of the Invention According to the present invention, since the first dielectric layer is formed by sputtering using a metal mask, it has good adhesion to the glass substrate, and it is possible to use a mask on top of the first dielectric layer. After forming a light-emitting layer, the light-emitting layer is patterned into a predetermined shape, so a light-emitting layer with uniform crystallinity and uniform thickness is formed on the entire surface, resulting in a thin film EL without peeling of the light-emitting layer or uneven brightness. You get a panel.

[Brief explanation of the drawing]

FIGS. 1A to 1D are thin films of an embodiment of the present invention.
FIG. 3 is a cross-sectional view of each step for explaining the method of manufacturing an EL panel. FIG. 2 is a sectional view of a thin film EL element, FIG. 3 is a schematic plan view of FIG. 2, and FIG. 4 is a sectional view of a thin film EL panel. FIG. 5 is a cross-sectional view during film formation for explaining a conventional method for manufacturing a thin-film EL panel, and FIG. 6 is an enlarged cross-sectional view of a main part of a film formed by the conventional method. DESCRIPTION OF SYMBOLS 1... Glass substrate, 2... Transparent electrode, 3... First dielectric layer, 4... Light emitting layer, 5... Second dielectric layer, 6... Back electrode, 19... Metal mask,
24...Photoresist film.

Claims (1)

[Claims] 1(a) forming a transparent electrode on a glass substrate; (b) sputtering a dielectric material onto the transparent electrode using a metal mask to form a first dielectric layer in a predetermined pattern; (c) forming a light-emitting layer on the first dielectric layer without using a metal mask; and (d) patterning the light-emitting layer into a predetermined shape. A method for manufacturing a thin film EL panel characterized by the following.