JPH02183994A - Multi-color thin el element - Google Patents

Abstract

PURPOSE:To unify luminous intensity by arranging a pattern-processed pollution preventing layer and an etching-resistant layer preventing the etching on a phosphor thin film on a pattern-processed phosphor thin film covered with a pollution preventing layer. CONSTITUTION:An ITO thin film is formed on a glass substrate 1 by spattering, this thin film is processed by the photolithography process, and a stripe-shaped transparent thin film 2 is formed. SrTiO3 is spattered on it at the preset temperature in the AR atmosphere containing O to form the first insulator layer 3. A phosphor thin film made of ZnS:Tb is formed on the layer 3 by the electron beam deposition method. This thin film is processed by the photolithography process using nitric acid or the like to form a stripe-shaped green emitter layer 4. BaTa2O6 is rf-spattered on it in the AR atmosphere to form an etching- resistant layer 7. A red emitter layer 5 covered with a pollution preventing layer 9 is formed, an etching-resistant layer 8 is formed on it in the AR atmosphere containing N gas, a blue emitter layer 6 covered by a pollution preventing layer 10 is formed, and the second insulating layer 11 is obtained on the layers 4, 5 and 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a multicolor thin film EL device, and in particular to a multicolor thin film whose luminance is uniform over a wide area, from a low brightness region to a high brightness region. This relates to the E1-element.

2. Description of the Related Art In recent years, multicolor thin film E1-4 elements have been actively researched as flat displays used in computer terminals and the like. Such a thin film EL element is formed as follows (see FIG. 2).

A tin-doped indium oxide (ITO) thin film is deposited on a glass substrate IF, and a striped transparent electrode 2 is formed by a photolithography process. On top of that, S: ]Na, Y2O3
, SrT: (h) is formed by a vacuum evaporation method or sputtering method.Subsequently, on the first insulator N3, a green light-emitting phosphor composed of, for example, Z.S:Tb,F is formed. A thin film is formed by a vacuum evaporation method or a sputtering method.Then, it is processed into a stripe shape by a photolithography process, and after removing the photoresist, a red light-emitting phosphor thin film consisting of, for example, c, s: E, is formed by a vacuum evaporation method or a sputtering method. After that, it is processed into a stripe shape using a photolithography process, and after removing the photoresist, a blue-emitting phosphor thin film made of, for example, S, S:C, is formed using an α-vacuum deposition method or a sputtering method. Processed into stripes and removed the photoresist, the luminescent layer 4.5
．． Complete 6. Next, a second insulating layer 11 made of S+3Na, Y2O1, BaT-206, etc. is formed on one of the light emitters rt54.5.6 by vacuum evaporation or sputtering, and finally a transparent electrode is formed. A thin film E1-element is completed by forming a back electrode 12 consisting of striped ^1 thin strips in orthogonal directions.
(See Publication No. 46192).

Problems to be Solved by the Invention However, when a multicolor thin film EL element is formed using conventional techniques, the emission start voltage varies depending on the location even within the same substrate, causing uneven emission, especially at low brightness levels. There was a problem.

Therefore, the display quality during gradation display is insufficient, and there is a problem in full-color display in particular.

It is an object of the present invention to provide a multicolor thin film EL device that solves the problems of the prior art and has uniform luminance over a wide area.

Means for Solving the Problems The present invention provides a multi-f! ! In the thin film E f element, a contamination prevention layer is placed on top of the phosphor thin film patterned using photolithography technology to prevent contamination and dissolution caused by photoresist and developer. On the substrate surface containing the phosphor thin film covered with a layer,
Next, when patterning other types of phosphor thin films deposited, the patterned contamination prevention layer and the etch-resistant layer to prevent the phosphor thin film from being etched are arranged. This is a multicolor thin film EL device characterized by comprising a light emitting layer.

Function: It has been found that one of the causes of local differences in luminescence starting voltage and uneven luminescence within the same substrate is a difference in the surface condition of the phosphor thin film. This difference in surface condition may be caused by, for example, contamination by the photoresist or metal elements contained in the photoresist, or by dissolution or decomposition of the phosphor thin film by the developer.By protecting the surface of the phosphor thin film with a contamination prevention layer, the surface condition was able to keep it clean. Another cause is that due to the distribution of etching speed within the substrate, during the second and subsequent etching of the phosphor thin film, even the phosphor thin film that has already been patterned is partially etched, which causes the emission starting voltage to vary from place to place. may change,
By arranging the etching-resistant layer on the surface of the substrate including the anti-contamination layer, thin-film EL with uniform luminance over a wide area can be achieved.
It became possible to manufacture the device.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an element structure for explaining one embodiment of the multicolor thin film EL element of the present invention. A 11'0 thin film with a thickness of 300 nm was formed on a glass substrate 1 by sputtering. Next, the ITO thin film was processed using a photolithography process consisting of resist coating, exposure, development, etching, resist removal, etc., to form striped transparent electrodes 2. Then, by RF sputtering SrT;
= 3 was formed.

On the first insulator layer 3, a 560 nm thick phosphor thin film made of Z, S:Tb was formed by electron beam evaporation, and then closed heat treatment was performed at 500° C. in vacuum for 1 hour. .

This Z. A striped green phosphor layer 4 was formed on the S:Tb thin film by a photolithography process using a wet etching method using nitric acid, phosphoric acid, acetic acid, or the like. Thereon, an etching-resistant layer 7 with a thickness of 50 nm was formed by RF sputtering BaTa2O6 in an argon atmosphere. Subsequently, the thickness was 600 nm by electron beam evaporation method.
A phosphor thin film consisting of C, S:E and a contamination prevention layer consisting of ZnS were formed, and then heat treatment was performed at 500° C. for 1 hour in vacuum. This CaS:Eu'4 film and the anti-contamination layer were subjected to a photolithography process using a tri-etching method using methanol and argon gas to produce a striped red luminescent material r! coated with anti-contamination N9. i5
was formed. On top of that, etching-resistant N8 made of S;3N4 with a thickness of 50 nm was formed by sputtering 51 in an argon gas atmosphere containing nitrogen gas.Subsequently, an etching-resistant N8 made of S;3N4 was formed with a thickness of 700 nm by electron beam evaporation.
A phosphor thin film consisting of m S, S:C, and a thickness of 50n
A contamination prevention layer made of Al2O3 was formed in an amount of 100 m thick, and then heat treatment was performed at 500° C. for 1 hour in a vacuum. This S, S:C
, the thin film, and the contamination prevention layer were subjected to a photolithography process using a tri-etching method using methanol and argon gas to form a striped blue luminescent layer 6 covered with the contamination prevention layer 1O.

A second insulating layer 11 with a thickness of 300 nm is formed by RF sputtering B and TA206 in an argon atmosphere on the light emitting layer 4.5.6 formed in this manner.
was formed. Finally, a striped back electrode 12 made of A1 having a thickness of 250 ru++ was formed to complete a thin film EL device.

The brightness-voltage characteristics of the thin film EL element produced by the manufacturing method of the present invention at 6011□ were such that the difference in one emission starting voltage was 5 V or less within the entire emission area of 150 x 200 mm2. Furthermore, the light emission state was also uniform from the low voltage region to the high voltage region.

In this example, no contamination prevention layer was provided on the green phosphor thin film, but the Z,S:Tb phosphor thin film was not contaminated or dissolved by photoresist or developer. This is because of this. On the other hand, C, S:E
, S, S:C, and phosphor thin films are sometimes contaminated or dissolved by photoresist, developer, etc., so a contamination prevention layer such as ZoS or Al2O3 is provided. It is desirable that the contamination prevention layer be easily etched when the phosphor thin film covered with the contamination prevention layer is etched. Practically speaking, it is desirable that the ratio of the etching rate of the contamination prevention layer to the phosphor thin film covered with the contamination prevention layer be 0.5 or more. If the etching rate of the contamination prevention layer is lower than this value, uneven etching or etching residues may occur.

As the etching-resistant layer, Ha Ta 20s or 5r3 is used.
Although Na was used, it is practically sufficient that the etching rate ratio of the etching-resistant layer to the phosphor thin film provided on the etching-resistant layer is 0.5 or less, and other S, 02, S
Insulator thin films such as rT;0:+ and Ta2'5 could also be used. If this ratio is 0.5 or more, even the phosphor thin film that has already been patterned may be etched.The etching methods for the phosphor layer, where the emission start voltage tends to vary within the substrate, include nitric acid, phosphoric acid, A wet etching method using an aqueous solution such as acetic acid, a dry etching method using alcohol, carbon tetrachloride, etc., or a sputter etching method using a rare gas such as argon gas could be used.

As for the type of phosphor thin film constituting the luminescent layer, in addition to zinc sulfide-based phosphors, easily hydrolyzed phosphors such as calcium sulfide-based and strontium sulfide-based phosphors can also be used. Although the insulating layer type thin film EL element has been described, the present invention can also be applied to a single side insulating layer type thin film EL element that does not use a first insulating layer, or a DC type thin film EL element that does not use an insulating layer. Of course.

Effects of the Invention As explained above, the present invention can provide a thin film EL element with uniform luminance over a wide area from a low luminance region to a high luminance region. Therefore, it has great practical value, especially when forming a multicolor thin film EL element in which a luminance modulation function is essential.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a multicolor thin film EL device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional multicolor thin film EL device. l...Glass substrate, 2...ITO transparent electrode, ;(・
...First insulator layer, 4.5.6... Luminous layer, 7.8
,... Etching resistant layer, 9, IO... Contamination prevention layer, 11... Second insulator layer, 12... Back electrode.

Claims (4)

[Claims] (1) A multicolor thin film EL device is formed by laminating a transparent electrode, an insulator layer, a light emitter layer having two or more types of phosphor thin films, electrodes, etc. on a transparent substrate, and is patterned using photolithography technology. A contamination prevention layer is placed on the phosphor thin film to prevent contamination and dissolution by photoresist and developer, and the substrate surface including the patterned phosphor thin film covered with the contamination prevention layer is Next, when patterning other types of phosphor thin films that have been deposited, a structure in which an already patterned contamination prevention layer or an etching resistant layer is arranged to prevent the phosphor thin film from being etched. Multicolor thin film EL characterized by having a light emitting layer
element. (2) The multicolor thin film EL device according to claim 1, wherein the ratio of the etching rate of the contamination prevention layer to the phosphor thin film covered with the contamination prevention layer is 0.5 or more. (3) The multicolor thin film EL device according to claim 1, wherein the etching rate ratio of the etching-resistant layer to the phosphor thin film provided on the etching-resistant layer is 0.5 or less. (4) The phosphor thin film is made of zinc sulfide, strontium sulfide,
Claim 1 The main component is one or more types of calcium sulfide.
The multicolor thin film EL device described above.