JPH02135696A - Manufacture of el display panel - Google Patents

Abstract

PURPOSE:To manufacture an EL display panel in a short time by irradiating a substrate with gas in which any of Zn, strontium and Ca is evaporated, gas of hydrogen sulfide and the product produced by cracking the hydrogen sulfide and also the gas generated due to evaporation of such as element which mainly emits light repeatedly in this order. CONSTITUTION:A substrate 1 in which layers up to the first insulating layer 13 have been formed is disposed in a container 21. The container 21 is then made vacuous. Atoms of Zn and Mn formed by evaporating such as a metal 22 of Zn and that 23 of Mn among Zn, strontium and Ca by resistance heating deposition and gas of H2S heated in a cell 24 disposed in the container 21 are repeatedly radiated onto the substrate 1 in this order to form a luminous layer 14. Regarding to the radiation in order, a shutter 26 or 27 may be opened and closed in the case of radiating the atom of Zn or Mn. On the other hand, an air valve 28 is opened and closed when the H2S is radiated. Accordingly, a thin film EL display panel with high intensity, stable luminous characteristics and high reliability is manufactured in a short time.

Description

[Detailed Description of the Invention] [Summary] [Field of Industrial Application] The present invention relates to an EL display panel, which is a type of flat display panel.
The present invention relates to a method of manufacturing a display panel, and particularly to a method of manufacturing a light-emitting layer that provides a highly reliable and high-brightness display panel.

EL display panels have very thin light-emitting layers, and

Because the electrode layer has a Y matrix structure and has good dimensional accuracy, the displayed image is clear and has excellent display quality without any blurring of light emission. Furthermore, it has features such as the ability to easily achieve thinner and lighter panels and low power consumption, and is used in computer terminal display devices and the like.

Such an EL display panel is required to have high reliability and high brightness characteristics. The present invention provides such a panel with high reliability and high brightness.

[Conventional technology]

As shown in FIG. 4, a conventional EL display panel has a plurality of striped transparent electrodes made of, for example, a solid solution of indium oxide (Ink) and tin oxide (SnOz) (abbreviated as ITO) on a transparent glass substrate 1. 2 is provided.

On its upper surface, a luminescent material containing impurities, which becomes a luminescent center, is formed, for example, made of zinc sulfide (ZnS) containing manganese (Mn), through a transparent first insulation N3 made of silicon oxynitride (SiO, N, ''), etc. A light emitting layer 4 is laminated, and a plurality of strip-shaped back electrodes 6 made of aluminum (^l) etc. are formed on top of the layer 4 with a transparent second insulating layer 5 made of silicon oxynitride (SiO, N, ) etc. are disposed perpendicular to the transparent electrode 2, and a surface protection film 7 is further formed thereon.

Conventionally, in order to obtain a light-emitting layer without a dead layer in such a panel, ALE (atomic layer epitaxy) was used, in which a halide of the base metal constituting the light-emitting layer and H, S gas, which is not heated at room temperature, are alternately sprayed. ) is used.

Another method for ALE is to use Zn atoms as a base material,
A method has also been proposed in which the substrate is alternately irradiated with H and S gases that are not heated at room temperature.

[Problem to be solved by the invention]

In such conventional EL display panels, as described above, a halogen compound with a low vaporization temperature is used as a raw material for the light emitting layer. It is known that when a light emitting layer is formed using a halogen compound as a raw material, the halogen element remains as an impurity in the formed light emitting layer. These impurities are activated by the electric field of the display drive pulse, form unnecessary electronic levels in the energy band gap of the light emitting layer base material, and cause fluctuations and deterioration of the light emitting characteristics.

Further, when a light emitting layer is formed by alternately irradiating Zn and room temperature ths, ZnS growth will not occur unless the substrate temperature is maintained at at least 600°C or higher.

When using a glass substrate, the practical maximum temperature is at most 600"C, but if a light-emitting layer is formed by alternately irradiating Zn and Has at this temperature, one UZS irradiation time is more than 1 minute. A thin film that functions as a light-emitting layer cannot be grown unless it is maintained for a long time.Furthermore, H that remains in the processing container or has gotten under the substrate
Just by touching the substrate, lS reacts with Zn.

For the above reasons, it takes a long time of at least 50 hours to obtain a 400 nm light-emitting layer, which requires too many manufacturing steps, making it impossible to form a practical light-emitting layer for an EL display panel.

In view of the above-mentioned conventional drawbacks, the present invention aims to provide a method for manufacturing a panel having a light-emitting layer that has no or significantly less dead layer and contains almost no halogen element as an impurity in a short time and at low cost. This is the purpose.

[Means to solve the problem]

The method for manufacturing an EL panel of the present invention that achieves the above object is as follows:
In the production of an EL display in which display electrodes, at least one of which is translucent, are disposed on both sides of a light-emitting layer with an insulating layer interposed therebetween, the display electrode on one side and the insulating layer are formed in that order on an insulating substrate, and then the While heating the substrate in vacuum, the substrate is evaporated with a gas in which one of metal elements such as zinc, strontium, or calcium, hydrogen sulfide and its decomposition product gas, and an element or compound that becomes a luminescent center are evaporated. The method is characterized in that a light-emitting layer is formed on the insulating layer by repeatedly irradiating the gas in that order a predetermined number of times.

[For production]

In the manufacturing method of the present invention, a metal halide compound which is a luminescent base material is not used.

Therefore, halogen elements are activated by the electric field of the display driving pulse and form unnecessary electronic levels in the energy band gap of the metal compound that is the base material of the emissive layer, causing fluctuations and deterioration of the emissive characteristics. A high-brightness EL panel can be obtained without any impurities remaining in the EL panel.

Also, Zn, Sr (strontium), Ca
(calcium) which reacts with any element M and H! Since the decomposition products of S are alternately irradiated onto the substrate to form a light-emitting layer of metal sulfide, the metal atoms M that form the metal sulfide and the S atoms with which they are combined are regularly arranged. They are arranged to form metal sulfide crystals. Therefore, the cause of the formation of a dead layer with poor crystallinity can be removed, and a highly reliable light-emitting layer with good crystallinity and no dead layer can be obtained.

In addition, by thermally decomposing or ionizing HzS and irradiating it onto the substrate, the crystal growth rate of the metal sulfide can be increased, and the substrate temperature can be lowered than the reaction temperature of H, S and the metal element M. The decomposition products of S and S2, which react with M, are solid at room temperature, and excess S and St that do not contribute to the reaction with metal atoms M stick to the walls of the reaction vessel. There is less risk of the particles remaining inside or going under the substrate.

As a result, compared to the conventional ALE method, the time required to form the light emitting layer is reduced to at least 1/2 or less, and a panel can be obtained at low cost.

〔Example〕

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

FIG. 1 is a sectional view showing an EL display panel formed by the manufacturing method of the present invention.

As shown in the figure, a plurality of striped transparent electrodes 12 made of an ITO film are formed on a transparent glass substrate 11 by sputtering and photoetching, and then aluminum chloride (AfCj!s) and water (HzO) are applied thereon. Alumina film formed by CVD method using titanium chloride (TiCl x') and HzO as raw materials, or titanium oxide (TiO
z) Forming a transparent first insulating layer 13 made of a film or the like.

Furthermore, impurities that become luminescent centers are added on top of it, such as manganese (
After forming the light-emitting layer 14 of ZnS:)1n by the method of the present invention including Mn), a second insulating layer 15 made of the same material as the first insulating layer 13 is formed, and is perpendicular to the transparent electrode 12. After a striped back electrode 16 made of aluminum (A2) or the like is formed by vapor deposition or photoetching, a moisture-proof protective film 17 is formed thereon.

Now, in the first embodiment, in order to form the light emitting layer 14, as shown in FIG.
is installed in the container 21, and the inside of the container 21 is 2×10-'
Evacuate to a vacuum level of torr. Then, Zn atoms and Mn atoms formed by evaporating Zn metal 22 and Mn metal 23 as evaporation sources by the resistance heating evaporation method, and H2S gas heated in the cell 24 installed in the container 21 are applied to the substrate. The light-emitting layer 14 is formed by sequentially irradiating the light in that order alternately.

When irradiating Zn atoms or Mn atoms, one of the shutters 26 and 27 is opened and closed, and when H2S is irradiated, the air valve 28 is opened and closed.

This H2S is heated to 900°C by the heater 25 of the cell 24.
Heat to S2 and H! and introduced into the container 21.

The amount of introduction is set to 10 seconds using a mass flow controller (not shown).

In addition, Zn atoms, H, S gas (St, IIz, Ha
When the substrate is sequentially irradiated with 1IIn atoms (mixing of s) and 1IIn atoms, between each irradiation, the vacuum pump 30 connected to the container 21 increases the degree of vacuum in the container to I x 10-
' Evacuate until the vacuum level is higher than torr.

The above Zn atom, H! S gas (St, Hz, It
Assuming that the irradiation time of Mn atoms on the substrate is 2 seconds each, and the exhaust time after each source irradiation is 10 seconds, one cycle of the irradiation time of the three types of atoms and gases described above is 36 seconds. It takes 10 hours to perform this irradiation for 1000 cycles and form a light emitting layer with a thickness of 300 nm.

In this embodiment, H and S are decomposed and irradiated as Sts or S. The vapor pressure of S, S, is 1O- at 80℃
7 torr or less, most of it collides with the wall of the container and sticks there, and the amount floating inside the container is extremely small. On the other hand, although ths is a gas even at room temperature, it does not directly react with Zn or Mn, so it does not cause any problems even if it floats in the container. Furthermore, the vapor pressure of Zn and Mn is lower than that of S2, and as with 82 above, the amount floating in the container is extremely small. This small amount of residual gas can be almost completely removed by the evacuation process performed between alternate irradiations.

As a result, in the first embodiment, the crystallinity does not deteriorate due to the influence of residual gas, and the evacuation time between each irradiation is shortened.
A high-brightness light-emitting layer can be formed in a short time.

Further, in this example, the temperature for thermal decomposition of HtS is 900°C. Thermal decomposition of H and S begins at temperatures above 550°C.
At temperatures below 1000''C, only S2 is produced and S is not produced.

Since the above-mentioned S has a vapor pressure as low as that of ZnS, it sticks to the film by itself, and tends to make the stochiometry (stoichiometric bond) of ZnS excessive, reducing crystallinity. However, in this example, as mentioned above, since S is not generated by thermal decomposition, a ZnS film with good crystallinity can be obtained.

Furthermore, when the thermal decomposition temperature of Has is 900″C, S
Since almost no evaporation of t occurs, it is easy to process (cheap Si
cells can be used for pyrolysis. In addition, 110
If a Si cell is used at a temperature of 0° C. or higher, Si will evaporate and be included in ZnS, significantly impairing crystallinity.

In the above first embodiment, 1 (2S gas was heated to 900'C and introduced into the container in which the substrate was installed, but
Temperatures above °C may be used. Alternatively, a method may be used in which a counter electrode (not shown) is provided in the cell 24 and a high voltage is applied between the electrodes to ionize and irradiate the H2S gas.

Incidentally, the thin film EL display panel manufactured according to this example was manufactured at a luminescence threshold voltage of +30v1 and a pulse width of 25μS, 6
When driven at 0 Hz, a high brightness of 70 fL was obtained, and as a result of an accelerated life test conducted at 10 KHz for 60 hours, no decrease in luminance was observed, confirming that there was no change in luminous characteristics. .

FIG. 3 is an explanatory diagram of another embodiment of the present invention.

The panel structure formed in this second embodiment is the same as that in FIG.

In the second embodiment, in order to form the light emitting Jii 14, as shown in FIG.
.

Evacuate to a vacuum level of rr. Then, the substrate is sequentially moved onto each source partitioned by a partition wall, and Zn atoms and Mn atoms formed by evaporating the Zn metal 22 and Mn metal 23 as the evaporation sources by the resistance heating evaporation method, and further the container 21
The light emitting layer 14 is formed by alternately irradiating the substrate with H2S gas heated in the cells 24 inside. At this time, for example, when the substrate is above the Zn source 22, only Zn is irradiated, and when the substrate is next above the HzS source, the shutter 26 above the Zn source is closed and 11□8 is irradiated.

After the gas irradiation of each source, the inside of the container 21 is evacuated for 5 seconds by the vacuum pump 30.

The heating method and temperature of His are the same as in the first embodiment. In the second embodiment, the substrate is sequentially moved over three types of sources, and each source is partitioned with a partition wall 29, so mutual interference between the sources is minimized and a light-emitting layer with good crystallinity can be formed in a short time. Can be formed. Furthermore, if each partition is evacuated using a dedicated vacuum pump, mutual interference between the sources can be further reduced. In this way, 1 cycle 2
When rotated for 0 seconds, it takes only 6 hours to form a 300 nm light emitting layer compared to the first embodiment described above.

Further, in the second embodiment, since plasma can be isolated by the isolation wall 29, irradiation with Zn atoms or Mn atoms may be performed using a sputtering method. The same good results as in the first example were obtained with the thin film EL display panel manufactured according to the second example.

〔Effect of the invention〕

As is clear from the above explanation, according to the method of the present invention, the problem of dead layer formation in the light emitting layer is solved, and there is no fear of impurities such as halogen elements being included, so light is emitted with high brightness. Highly reliable thin film EL with stable characteristics
Display panels can now be manufactured in a short time, which is extremely useful in practice.

FIG. 4 is a cross-sectional view of an EL display panel formed by a conventional manufacturing method.

In the figure, 11 is a glass substrate, 12 is a transparent electrode, 13 is a first insulating layer, 14 is a light emitting layer, 15 is a second insulating layer, 16 is a back electrode,
17 is a protective film, 21 is a container, 22 is Zn, 23 is Mn
, 24 is a cell, 25 is a heater, 26.27 is a shutter, 28 is an air-driven pulp, 29 is a separating wall, and 30 is a vacuum pump.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an EL display panel formed by the manufacturing method of the present invention, FIG. 2 is an explanatory diagram of the apparatus used in the first embodiment of the present invention,

Claims (1)

[Claims] A display electrode (12,
16), after forming the display electrode (12) on one side and the insulating layer (13) in that order on the insulating substrate (11), the substrate is heated in vacuum while the substrate is heated. A gas in which a metal element such as zinc, strontium, or calcium has evaporated, a gas in which hydrogen sulfide and its decomposition products have evaporated, and a gas in which an element or compound that is the center of luminescence has evaporated are repeatedly applied a predetermined number of times in that order. irradiation to form a light-emitting layer (14) on the insulating layer (13).
) A method for manufacturing an EL display panel, the method comprising forming: Regarding the manufacturing method of EL display panels, dead layers with extremely poor crystallinity
less occurrence of layers that do not contribute to light emission, called er),
Aiming at manufacturing an EL display panel having a light-emitting layer that does not contain halogen elements as an impurity and is capable of high-brightness display, display electrodes, at least one of which is translucent, are arranged on both sides of the light-emitting layer with an insulating layer interposed therebetween. In the production of an EL display, after forming a display electrode on one side and an insulating layer on an insulating substrate in that order, a metal element such as zinc, strontium, or calcium is applied to the substrate while heating the substrate in a vacuum. A light-emitting layer is formed on the insulating layer by repeatedly irradiating a gas in which hydrogen sulfide and its decomposition products are evaporated, a gas in which an element or compound serving as a luminescence center is evaporated, in that order, a predetermined number of times. It consists of: