JPH0436992A - Manufacture of el element - Google Patents

Abstract

PURPOSE:To form a light emission layer having a stoichiometric composition and excellent in crystallinity even without high temp. on the base board by using a gas containing xenon as sputter gas in the sputtering process. CONSTITUTION:A clear electrode 2, SiO2 film 3, and No.1 dielectric substance layer 4 are formed one over another on a clear base board 1 in the form of a plurality of band-shaped films. A compound layer 5 consisting of SiO2 is formed in the formed of a film on the No.1 dielectric substance layer 4. Using xenon gas as the sputtering gas, sputters are made on a sputter target of SrS:Ce as sintered object obtained by 0.1 mol% doping of CeCl3 wherein St sulfide is used as the light emission center substance under the conditions of the pressure being 0.65 Pa, high frequency output 3.6 W/cm<2>, and base board temp. 200 deg.C. Thus a light emission layer 6 is formed in the form of a film on the compound layer 5. This light emission layer 6 is subjected to a 600 deg.C heat treatment under a vacuum for two hours.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an east-facing display device that is used as a means for displaying still images or moving images in a display device such as a terminal of a computer system. The present invention relates to a method for manufacturing an L element.

[Conventional technology]

In the manufacturing method of an EL element, transparent electrodes made of In2O5, SnO2, etc. are usually arranged on a transparent substrate such as a glass substrate, and then a first dielectric layer and a light emitting center are formed with 0.0. O
1~0. After sequentially laminating a light-emitting layer made of a supra-alkaline sulfide such as strontium sulfide (SrS) or zinc sulfide (Zn, S) doped with 4 mo 1% of rare earth, and a second dielectric layer, This process consisted of arranging back electrodes made of ff-Ni alloy or the like.

In particular, the EL characteristics of the light emitting layer formed by the above steps, such as luminance, are greatly influenced by its stoichiometric composition and crystallinity.

For example, in Japanese Patent Publication No. 65-4m2:1, a light-emitting layer is formed by sputtering using a mixed gas of argon, nitrogen, l\lium, or neon as a sputtering gas, and this light-emitting layer is It is described that the crystallinity of the light emitting layer can be improved by heat treatment at ~400°C.

[Problem to be solved by the invention]

However, in the method described in the above publication, when forming a light emitting layer by sputtering, if a mixed gas of argon and nitrogen, helium, or neon is used as a sputtering gas, a film with a composition close to the stoichiometric composition of the light emitting layer can be obtained. However, sufficient crystallinity cannot be obtained, and even if the crystallinity is increased by heat treatment, the crystallinity increases to some extent, but the crystallinity of the heat-treated surface is not good, so it is difficult to obtain a film with sufficient crystallinity. However, the improvement in luminescent properties was insufficient.

Furthermore, in the method of the above-mentioned publication, the film forming conditions for achieving the best crystallinity of the light-emitting layer film due to the scattering and swaying are when the substrate temperature is as high as 350°C or higher, so it is necessary to increase the crystallinity of the film. Eventually, the substrate temperature must be raised, and as the substrate temperature increases, for example, in the case of a light-emitting layer made of sulfide doped with rare earth elements, sulfur, which has a high vapor pressure, is likely to be depleted and the stoichiometric composition will be reduced. There was a drawback that a light-emitting layer having the same structure could no longer be obtained.

Therefore, the object of the present invention is to provide, by sputtering,
By forming a light-emitting layer with excellent crystallinity and a stoichiometric composition without raising the substrate temperature as in conventional methods, the crystallinity is further improved by heat-treating it. The present invention provides a method for producing an EL element with excellent light emitting characteristics.

[Means to solve the problem]

The present invention has been made to achieve the above object, and the method for manufacturing an EL element of the present invention includes a transparent electrode, a first dielectric layer, a light emitting layer, a second dielectric layer, and a transparent electrode on a transparent substrate. In the method for manufacturing an EL element obtained by laminating back electrodes, the step of forming the light emitting layer includes the step of forming the light emitting layer by sputtering using a gas containing xenon as a sputtering gas; The method is characterized in that it includes a step of heat-treating the formed light-emitting layer.

Further, it is preferable that the amount of xenon in the sputtering gas when forming the light emitting layer by sputtering is north of G Ov o I 96 with respect to the sputtering gas in the apparatus. This is because when the amount of xenon is less than 60 v o ] 96 , the effect of improving the stoichiometry and crystallinity of the light emitting layer is small. Furthermore, preferably 80 v o
196 or more.

Further, as the gas that can be mixed with xenon during sputtering, gases commonly used as sputtering gases such as argon, neon, and helium can be used.

By using a gas containing xenon as a sputtering gas, a light-emitting layer with high crystallinity and a stoichiometric composition can be obtained even when sputtering is performed at a low substrate temperature during film formation. Furthermore, since the light-emitting layer is formed at a low temperature, even if heat treatment is performed, the crystallinity of the light-emitting layer can be further improved while maintaining the stoichiometric composition.

If the heat treatment temperature at this time is less than 300°C, the effect of the heat treatment will not be sufficiently exhibited, and if it exceeds 700°C, sulfur will be easily lost from the light emitting layer.
0℃ is good. Further, if the heat treatment time is less than 0.5 hours, the effect of the heat treatment will not be sufficiently exhibited, and even if it exceeds 5 hours, the improvement effect of the heat treatment will hardly change.

〔Example〕

Next, examples of the present invention will be shown, but the present invention is not limited to these examples.

FIG. 1 is a sectional view of an EL element according to an embodiment of the present invention. The present invention will be explained below with reference to FIG.

First, a transparent thin conductive film (thickness: 2000 mm) made of indium oxide mixed with tin oxide was deposited on a transparent substrate l made of aluminosilicate glass (for example, NA40 manufactured by HOYA Corporation) measuring 240 x 240 mm using a vacuum evaporation method. After forming a film using the method described above, a plurality of band-shaped transparent electrodes 2 (in FIG. one of which is shown in longitudinal section).

Next, using silicon dioxide as a sputtering target, an argon atmosphere, a pressure of 0.45 Pa, and a high frequency output of 3.3 W/
A SiO2 film 3 having a thickness of about 200 mm is formed on the transparent electrode 2 by sputtering under the conditions of al.

Next, using silicon as a sputtering target, an argon atmosphere containing approximately 3096 nitrogen gas and a pressure of JjO, 45
Reactive sputtering was performed under conditions of high frequency output of 6.6 W/ai, and a film thickness of 20 mm was formed on the SjO2 film 3.
A dielectric layer 4 made of j*N+ having a luminescence of approximately 0.0000000000 is formed.

Furthermore, silicon dioxide was used as a sputtering target in an argon atmosphere, at a pressure of 0.45 Pa, and at a high frequency output of 3.3 W.
Sputtering is performed under the condition of /cn to form a compound layer 5 having a thickness of about 300 and consisting of 5jOz on the first dielectric layer 4.

After that, strontium sulfide (SrS) doped with 0.1 mo1% of Ce CI a as a luminescent center substance and sintered was used as a sputtering target, and xenon gas was used as a sputtering gas at a pressure of 0, (i5Pa, and a high frequency output of 3). Sputtering was performed under conditions of 6 W/al and a substrate temperature of 200°C to form a film with a thickness of 1000 nm on the compound layer 5.
The light emitting layer 6 is formed by about 0 people.

Thereafter, the light-emitting layer 6 is heat-treated in vacuum at a temperature of 600° C. for 2 hours.

Thereafter, the Sj+N4 thin film layer 7a is deposited to a thickness of about 1000 luminous intensity by the reactive sputtering method in the same manner as in the deposition of the first dielectric layer 4.

Furthermore, using metal tantalum as a sputtering target, an argon atmosphere containing approximately 30% oxygen gas and a pressure of 0.6
Reactive sputtering was performed under conditions of high frequency output of 6.61 J/cd to form a thin film layer 7b of light-emitting a2O with a thickness of about 2000 on the 5i8N film 7a, and 5j
=N=second layer consisting of thin film 7a and TazOs thin film layer 7b
A dielectric layer 7 is formed.

Finally, an All thin film is formed on the T a 20 s thin film layer 7b, and after photolithography is applied to this, an etching process is performed using a mixed solution of nitric acid and phosphoric acid as an etching solution, and a plurality of A strip-shaped back electrode 8 is formed so as to be perpendicular to each of the transparent electrodes 2 (in the direction perpendicular to the plane of the paper in FIG. 1).

Next, as a comparative example, the same example was used except that when forming the light emitting layer 6, a mixed gas of argon 60 v o I 96 and helium 40 v o 196 was used instead of xenon gas and the substrate temperature was 350°C. An EL device was produced in the same manner as described above.

FIG. 2 is a graph showing a comparison between the luminance characteristics of the EL device manufactured by the method of the above-described example and the luminance characteristics of the EL device manufactured by the method of the comparative example. In Figure 2, the vertical axis represents luminance (unit: c
d/n? , c d : candela), and the horizontal axis is the applied voltage (unit: v).

Curve A shows the case according to the present example, and curve B shows the case according to the comparative example.

As is clear from the above graph, it was confirmed that the EL device manufactured according to this example had much superior luminance compared to the EL device manufactured according to the comparative example.

In this example, 5iOz was used for the compound layer 5, but 5iOz was used for the compound layer 5.
Z r Oz or T j 02 may be used instead of iOz, and the compound layer 5 may not be provided.

Further, in the above embodiment, a single layer was used as the first dielectric layer and a double layer was used as the second dielectric layer, but each may be a single layer or a multilayer. Furthermore, as a dielectric layer,
S is N4, Taz Os, 8 J220s, Y
201, ZrO2, BaTa20g, PbTjOs
, silicon oxynitride, etc., or a multilayer combination of these materials.

Furthermore, 5102 between the transparent electrode 2 and the first dielectric layer 4
The membrane 3 may not be provided.

In addition, the light emitting layer 6 was made of SrS doped with CeCl3, but the dopants were EuCI=, SmC]g, Pr
C]s 1. Rare earth compounds such as TbFs and DyFi and rare earth elements alone may be used, and instead of SrS, CaS, B
aS may be used, and the target used when forming the light emitting layer 6 does not need to be a sintered powder or the like.

In this embodiment, the substrate temperature for forming the light emitting layer was 200° C., but it does not need to be 200° C., and may be any temperature that does not cause loss of a substance with a high vapor pressure such as sulfur.

〔Effect of the invention〕

As detailed above, the EL element of the present invention! ! ! According to the method, by using a gas containing xenon as a sputtering gas during sputtering, a light emitting layer with excellent crystallinity and a stoichiometric composition can be formed without raising the substrate temperature. By heat-treating it, the crystallinity can be further improved, resulting in an EL element with excellent light-emitting characteristics.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an ET device manufactured according to an embodiment of the present invention. FIG. 2 shows the E produced by the method of one embodiment of the present invention.
3 is a graph showing the luminance characteristics of an L element r and an EL element manufactured by a method of a comparative example. 1... Transparent substrate, 2... Transparent electrode, 3... SiO
2 thin film, 4... first dielectric layer, 5... compound layer, 6
...Light emitting layer, 7...Second dielectric layer, 7a-3isN
4 thin film, 7b"'TazOa thin film, 8... back electrode. Patent applicant Po-Ya Co., Ltd.

Claims (1)

[Claims] 1. In a method for manufacturing an EL device obtained by laminating a transparent electrode, a first dielectric layer, a light emitting layer, a second dielectric layer, and a back electrode on a transparent substrate, the step of forming the light emitting layer comprises using a sputtering gas as a sputtering gas. A method for manufacturing an EL device, comprising the steps of forming a light-emitting layer by sputtering using a gas containing xenon, and heat-treating the formed light-emitting layer.