JP2001313167A - Color el panel and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color EL panel having parallel patterned light emitting layers for a high quality display, and to provide a manufacturing method of the color EL panel by preventing increase of power consumption and lowering of brightness. SOLUTION: A luminous layer 14 is formed by etching a luminous layer material so as to form a plurality of patterns in parallel on an insulation layer 13 formed on one surface of a substrate 11, and a film surface improving layer 15 is formed on the luminous layer by the film forming method which does not include etching, hereupon, a part of the luminous layer intended to make illuminate is covered with the material having crystalline affinity with the luminous layer material, and after forming another insulation layer 16 on the above, the color EL panel is manufactured including a heat treating process. ZnS: Mn and SrS: Ce are used for the luminous layer material and ZnS is used for the material of the film surface improving layer 15. The heat treatment is carried out with the temperature of more than 400 deg.C and less than the temperature transforming or transmuting the substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electroluminescent (E) device in which a light emitting layer is formed by juxtaposing a plurality of light emitting layer materials by patterning.
L) The present invention relates to a color EL panel composed of elements, and more particularly, to a filter type color EL panel composed by combining a color filter with the EL element and a method of manufacturing the same.

[0002]

2. Description of the Related Art A thin film EL panel is composed of a lower electrode, a lower insulating layer,
It has a structure in which a light emitting layer, an upper insulating layer, and an upper electrode are sequentially laminated, and light emission is obtained by applying an AC voltage between the upper electrode and the lower electrode. A thin-film EL panel that has been practically used is a yellow monochrome display using a ZnS: Mn thin film for a light-emitting layer. A light-transmitting conductive film is used for a lower electrode, a metal electrode is used for an upper electrode, and light is emitted from the lower electrode side. Take out.

[0003] With the recent development of the information industry, the demand for color displays is increasing, and the application of thin-film EL panels to colorization is being actively promoted. In order to color the thin film EL panel, many filter type thin film EL panels in which a thin film EL element and a color filter are opposed to each other have been developed. The filter system refers to a system in which a single color light emitted from a thin film EL element is separated by a color filter composed of a plurality of organic substances to obtain a plurality of emission colors.

[0004] In addition to a filter system, a thin-film EL panel is provided with a color juxtaposition system in which luminous layers of different luminous colors are arranged to form picture elements, and a EL system of different luminous colors.
A main method is a double-substrate method in which EL elements of different emission colors are formed on two substrates and the two elements are overlapped, and a lamination method in which elements are stacked and laminated.

[0005] The filter system has the advantage that the EL element is provided with one kind of light-emitting layer, which simplifies the manufacturing process and makes it easy to manufacture, and can reduce the manufacturing cost. Has been adopted. However, since a single-color light-emitting layer having a broad light-emission spectrum is separated into a plurality of light-emission colors by a color filter, there is a problem that some of the light-emission spectrum is cut off by the color filter and the luminance tends to be insufficient.

In order to solve the above problem, a plurality of luminescent layer materials exhibiting an emission spectrum close to a desired luminescent color are patterned in accordance with a desired color, so that a luminescent layer formed in a juxtaposed manner is used for an EL panel. Consider that. At present, for the purpose of obtaining light emission of a desired emission color itself, it is not necessarily that color filters are not employed at all because of problems such as luminance and life. In consideration of the luminance due to the desired emission color, the type using both the juxtaposition method and the color filter method can obtain higher luminance.

A plurality of light emitting layer materials are patterned to form a light emitting layer by a juxtaposition method, a color filter is combined with an EL panel, and light emitted from the EL element is separated by the color filter. This makes it possible to use a light-emitting layer material that emits light close to each color, so that the portion where the light emission spectrum is cut by the color filter is reduced, and the light emission efficiency of the panel is apparently increased, and as a result, As a result, it is possible to improve the luminance of the color EL panel.

A technique of forming a color EL panel by juxtaposing a method by patterning a light emitting layer is disclosed in Japanese Patent Application Laid-Open No. 61-1 / 1986.
No. 3597. In the publication, an etching technique, a photolithography method, a mask evaporation method, and the like are proposed as a patterning method of the light emitting layer. As a light emitting layer patterning method for a color EL panel, the pixels of the panel are very small and the pixel density is high, and the light emitting layer material characteristics are well known.
Generally, an etching technique is used.

[0009]

In the color EL panel of the juxtaposition type in which the color filters are combined as described above, the light emitting layer is patterned by etching. When viewed in detail, the surface of the light emitting layer has a very rough shape. When an EL element is formed by forming an upper insulating layer and an upper electrode on a roughened light emitting layer, crystal defects are likely to occur in the roughened portion, so that there are many shallow levels of charge between the light emitting layer and the interface of the insulating layer. The EL element starts to emit light due to the formation of the light-emitting layer where the electric field is low, and the luminance-applied voltage characteristic of the EL element characteristics is not sharp.

Usually, an EL element exhibits a sharp luminance-applied voltage characteristic in which the luminance sharply increases at a threshold voltage which is a light emission start voltage. If the luminance-applied voltage characteristic is not steep, a large modulation voltage is required for the color EL panel, and the power consumption of the panel increases. In addition, since electric charge flows at a low light emitting electric field, a strong electric field is not applied to the light emitting layer, and the energy of the electric charge flowing in the light emitting layer is reduced, and as a result, the light emission luminance is reduced.

Therefore, it is necessary to take measures against a decrease in panel power consumption caused by deterioration of the luminance-applied voltage characteristic and a decrease in luminance due to the fixed modulation voltage of the drive circuit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color EL panel having a good display quality by preventing an increase in power consumption and a decrease in light emission luminance in a color EL panel of a juxtaposition type in which a light emitting layer of an EL element is patterned. To provide.

[0013]

According to the present invention, there is provided a semiconductor device comprising: a substrate; upper and lower electrodes disposed on one side of the substrate; two insulating layers disposed between the upper and lower electrodes; A light-emitting layer in which a plurality of light-emitting layer materials are patterned by etching in contact with the insulating layer, and a light-emitting layer which is in contact with the light-emitting layer on the light-emitting layer and does not include etching by a material having good crystalline compatibility with the light-emitting layer material A color EL panel having an electroluminescent element including a film surface improving layer formed by a film forming method and covering a light emitting layer portion to emit light.

According to the present invention, in a color EL panel constituted by a juxtaposition system for patterning a light emitting layer of an EL element, the light emitting layer material has a crystal structure close to the entire surface of the light emitting layer where light emission is desired or light emission. Since the film surface improvement layer is formed using a material that is easily linked to the crystal of the layer material,
The continuity of the crystal of the light emitting layer is improved at the patterning portion of the light emitting layer. Since the light-emitting layer damaged by the etching process and deteriorated in crystallinity, the surface of the film surface improvement layer formed by various film forming methods such as a vapor deposition method and a sputtering method not including the etching process has better crystallinity, Between the insulating layer and the film quality improving layer, a shallow level of charge cannot be formed due to crystal defects, and a deep level of charge is formed. As a result, the luminance-applied voltage characteristic of the EL element can be steeply maintained, so that it is possible to prevent an increase in the power consumption of the panel and a decrease in the luminous luminance.
An L panel can be configured.

The present invention is characterized in that a color filter formed on a light-transmitting substrate is provided so as to face the electroluminescent element.

According to the present invention, light emitted from an EL element having a plurality of patterned light emitting layer materials is separated by using a color filter, so that light emitting layer materials exhibiting light emission close to each color can be used. As a result, the portion where the emission spectrum is cut by the color filter is reduced, the panel emission efficiency is apparently increased, the brightness of the color EL panel can be improved, and the color EL panel with good display quality can be obtained. Can be configured.

According to the present invention, the film thickness dm of the film surface improving layer is provided.
(M) is the relative permittivity εm of the film surface improving layer, the amplitude value of the applied voltage waveform to start light emission determined by the driving circuit of the color EL panel is Va (V), and the relative permittivity of the light emitting layer is εp, the threshold electric field of the light emitting layer at which the light emitting layer starts to emit is Et
h (V / m), the thickness of the light emitting layer is dp (m), the sum of the thicknesses of the two insulating layers is di (m), and the sum of the apparent dielectric constants of the two insulating layers is εi. Where dm ≦ (εm × Va) / (εp × Eth) −εm × dp / εp−
It is characterized by being selected so as to satisfy the relationship of εm × di / εi.

According to the present invention, by setting the film thickness of the film surface improving layer to be equal to or less than a certain film thickness, the voltage necessary for causing the EL element to emit light as in the case where the film thickness exceeds the certain film thickness is reduced to the designed voltage. When the modulation voltage of the driving circuit of the color EL panel is fixed, the luminance is lowered because the modulation voltage cannot be obtained and the EL element does not emit light even when the maximum voltage applied by the driving circuit is applied. No problem. In the case where the light emitting layer is formed by juxtaposition of a plurality of different materials, dm is calculated from the above formula for each material portion, and the smallest dm among them is EL.
What is necessary is just to set it as the upper limit of dm of the whole element.

The present invention comprises a step of forming a lower electrode and an insulating layer on one surface of a substrate, and a step of forming a luminescent layer on the insulating layer by patterning a plurality of luminescent layer materials by etching and juxtaposing them. Forming a film surface improving layer on the light emitting layer by using a material having good crystallinity compatibility with the light emitting layer material, covering a light emitting layer portion to emit light, and using a film formation method not including etching; After forming another insulating layer on the surface improving layer, the method includes a step of heat-treating the laminated layer and a step of forming an upper electrode on the heat-treated insulating layer.

According to the present invention, in a color EL panel constituted by a juxtaposition system for patterning a light emitting layer of an EL element, a light emitting layer material or a crystal structure is close to the entire surface of the light emitting layer where light emission is desired. Since the film surface improvement layer is formed using a material that is easily linked to the crystal of the layer material,
The continuity of the crystal of the light emitting layer is improved at the patterning portion of the light emitting layer. Since the light-emitting layer damaged by the etching process and deteriorated in crystallinity, the surface of the film surface improvement layer formed by various film forming methods such as a vapor deposition method and a sputtering method not including the etching process has better crystallinity, Between the insulating layer and the film quality improving layer, a shallow level of charge cannot be formed due to crystal defects, and a deep level of charge is formed. In addition, the heat treatment improves the interface state between the patterning surface of the light emitting layer of the EL element and the film surface improving layer, and improves the crystallinity at the interface to reduce crystal defects. It is possible to manufacture a color EL panel with good display quality that can be kept steep and prevent an increase in panel power consumption and a decrease in light emission luminance.

According to the present invention, ZnS: Mn is used for the light emitting layer material.
And when using SrS: Ce and ZnS as a material of the film surface improving layer, in the heat treatment step,
It is characterized in that the temperature is 400 ° C. or higher.

According to the present invention, Zn is used as a light emitting layer material.
S: Mn and SrS: Ce, ZnS as a film surface improving layer
Is performed at 400 ° C. or higher, so that the crystallinity in the vicinity of the interface between the film surface improving layer and the light emitting layer is improved and crystal defects are reduced.

The present invention is characterized in that in the heat treatment step,
The temperature is set to a temperature lower than the lower one of the deformation temperature and the transformation temperature of the substrate.

According to the present invention, since the heat treatment is performed at a temperature lower than the temperature at which the substrate is deformed and deteriorated, the panel yield is improved and the panel cost is improved without causing the panel deformation during and after the manufacture of the color EL panel. Can be reduced, and deterioration of display quality due to distortion of the panel can be prevented.

[0025]

FIG. 1 is a sectional perspective view of a color EL panel according to an embodiment of the present invention. The color EL panel includes an EL panel substrate 123, a color filter substrate 120, and a resin adhesive 115. The EL panel substrate 123 is made of E
It includes an L element substrate 119, an insulating liquid 20, a sealing plate 18, an injection hole 19, a sealing plate 110, and a sealing resin 117.

The EL element substrate 119 has, for example, a thickness of 1.
An EL element 118 is formed on a substrate 11 which is a glass substrate having a size of 1 mm and a glass size of 150 mm × 110 mm. The EL element 118 is sequentially connected to, for example, ITO (In
transmissive lower electrode 12 having a thickness of 50-500 nm, a lower insulating layer 13 having a Si ₃ N ₄ / SiO ₂ laminated film having a thickness of 200-500 nm, ZnS: Mn and SrS: Ce at 300-1000 nm
The light-emitting layer 14, Z patterned in a stripe
nS: a film thickness of 1 using ZnS having the same crystal structure as Mn.
Film surface improving layer 15 formed to 50 nm, SiO ₂ / Si ₃ N
An upper insulating layer 16 in which a _four- layer film is formed with a thickness of 50 to 500 nm, and a translucent upper electrode 17 in which ITO is formed with a thickness of 100 to 800 nm are stacked.

The film surface improving layer 15 includes a light emitting layer of ZnS: M
A material having good crystalline compatibility with the light-emitting layer, such as ZnS, which is the same as the base material of n, is used. Although ZnS has a different crystal structure from SrS, ZnS has good crystal compatibility and is often used as a charge accelerating layer of a blue-green light-emitting element using SrS: Ce as a light-emitting layer. Therefore, there is no problem even if the ZnS layer is used on SrS: Ce in the sense that the charges flow smoothly in the light emitting layer.

If the film surface improving layer 15 is a substance that emits light, the light emitting layer becomes meaningless when patterned, and if the film surface improving layer 15 shines, the emission color of the EL element changes and the display quality of the panel deteriorates. Therefore, an undoped (non-doped) luminescent layer material having no luminescent center is used for the film surface improving layer 15. The thickness of the film surface improving layer 15 is set to a certain thickness or less as described later.

The color filter substrate 120 has a thickness of 1.1.
mm on a surface of a transparent substrate 111 such as a glass plate,
Red, green and blue color filters 11 having a thickness of 1.2 μm
2 are sequentially formed in parallel in a stripe shape, and a region where each color filter 112 is overlapped serves as a black mask 113.

The EL element substrate 119 and the color filter substrate 120 are bonded by the resin adhesive 115 on the EL element 118 side so that the EL element 118 and the color filter 112 have a very short distance of about 20 μm without contacting each other. Laminated. The resin adhesive 115 is not applied to the entire periphery of the color filter substrate 120, but is applied to four corners or a part of one side of the color filter substrate 120.

The EL element substrate 119 and, for example, a plate having a thickness of 1.
One side of 8 mm glass is dug to a depth of 0.7 mm leaving a frame portion, and a sealing plate 18 provided with an injection hole 19 is provided.
Are bonded by a sealing resin 117 such as an epoxy resin provided around the display section. When the insulating liquid 20 is injected from the injection hole 19 into the gap between the EL element substrate 119 and the seal plate 18, the resin adhesive 1
Since 15 is applied to the four corners and a part of one side of the color filter substrate 120, the space between the EL element 118 and the color filter 112 is also filled with the insulating liquid 20. Injection hole 1
Reference numeral 9 denotes an EL panel substrate 1 sealed by a sealing plate 110.
23 are formed.

FIG. 2 is a plan view of the color EL panel of FIG. When viewed from the normal direction 21, the lower electrode 12 and the upper electrode 17 form a lattice shape orthogonal to each other, and a pixel 216 is formed by the intersection of the lower electrode 12 and the upper electrode 17. A black mask 113 is formed between the stripe-shaped color filters 112, and a color filter substrate 120 is formed by the translucent substrate 111, the color filter 112, and the black mask 113.

FIG. 3 shows that ZnS: Mn is formed by using a film surface improving layer.
4 is a graph showing luminance-applied voltage characteristics of an EL element having a light emitting layer. FIG. 4 is a graph showing the luminance-applied voltage characteristics of an EL element having no film surface improving layer and using ZnS: Mn as a light emitting layer. The element structure of the EL element used in FIG. 3 is the same as that of FIG. 1 except that the light emitting layer 14 is not patterned and the color filter substrate 120 is not provided.
Since the film surface improving layer uses ZnS, it has extremely good crystalline compatibility with the light emitting layer.

The element structure of the EL element used in FIG. 4 is the same as the element structure of the EL element in FIG. 3 except that there is no film surface improving layer. 3 and 4, ZnS: Mn of the same lot is used for the light emitting layer, and the frequency is 100H.
The measurement was performed with the same AC pulse voltage waveform having z and a pulse width of 35 μm.

The EL element is driven by a modulation voltage during driving.
The non-light emitting state of the pixel is determined. The modulation voltage is a difference between a voltage having a luminance of 1 ft-L or less and a voltage L50 at the time of light emission at which a required luminance higher than 1 ft-L can be sufficiently obtained, and the maximum value is practically determined by the relationship of the performance of the driving circuit. , About 50V
The degree is taken. The voltage L50 at the time of light emission is represented by L50 = threshold voltage + modulation voltage, assuming that a voltage indicating luminance of 1 ft-L is a threshold voltage. When the luminance of the panel is 1 ft-L or more, the pixels appear to emit light to human eyes, and the contrast with the light emission is reduced, and the display quality of the panel is lowered. A lower value is chosen. Since the maximum value of the voltage that can be applied during light emission is a fixed value, the luminance-applied voltage characteristic of the panel needs to be steep.

In FIG. 3, since the vicinity of 1 ft-L is steep, the threshold voltage is about 170 V and the modulation voltage is 50
Assuming that the voltage is V, the voltage L50 at the time of light emission is about 220 V, and a luminance of about 100 ft-L is obtained. In FIG.
Light emission starts at a low voltage, and is gentle around 1 ft-L, the threshold voltage is around 155 V, and the modulation voltage is 50
V, the voltage L50 at the time of light emission is 205V, and the luminance is 5
It is considerably low at about 5 ft-L. As a result, when a conventional EL element having no film surface improving layer is used for a color EL panel, display quality is deteriorated. On the other hand, in a color EL panel of the present invention using an EL element having a film surface improving layer, It can be seen that the luminance-applied voltage characteristic of the EL element can be kept steep to prevent an increase in power consumption of the panel, and a decrease in emission luminance can be prevented, thereby improving display quality.

The EL element emits light when electric charges flowing in the light emitting layer excite a light emitting center in the light emitting layer. Mainly the additive in the light emitting layer becomes the light emission center. 1M for this excitation
A high electric field of V / cm or more is required, and in order to make the EL element emit light efficiently and with higher luminance, it is necessary to allow the charge to flow smoothly in the light emitting layer. For this purpose, it is necessary to allow the charge flowing through the insulating layer and the light emitting layer to flow when a high electric field is applied to the light emitting layer.
It is essential that the electric charge stored between the light emitting layer and the insulating layer is captured at a deep level.

In the conventional EL device having no film surface improving layer, the electric charge trapped between the light emitting layer and the insulating layer tends to be at a shallow level, whereas in the EL device having the film surface improving layer, the electric charge trapped is at a deep level. Since the positions are formed, a color EL panel having high luminance can be efficiently formed.

In the color EL panel, it is necessary to set the thickness of the film surface improving layer 15 to a certain thickness or less in order not to cause a problem such as a decrease in luminance or no emission of light.

When the thickness of the light emitting layer is dp (m), the threshold electric field of the light emitting layer at which the light emitting layer starts to emit light is Eth (V / m), and the voltage applied to the light emitting layer is Vp (V), the light emitting layer emits light. For this purpose, dp × Eth ≦ Vp (1) is sufficient. When viewed electrically, an EL element having a film surface improving layer is equivalently connected in series with three types of capacitors, that is, a film surface improving layer capacitance Cm, a light emitting layer capacitance Cp, and a total capacitance Ci including the upper and lower insulating layers. It can be regarded as a series connection of three capacitors. Assuming that the total capacitance when Cm, Cp, and Ci are connected in series is the total capacitance C of the EL element, the voltage applied to the film surface improving layer is Vm, and the voltage applied to the insulating layer is Vi, the voltage Va is applied to this element. From the formula showing the electrical relationship, the amount of charge stored in each capacitor when applied is: C × Va = Cm × Vm = Cp × Vp = Ci × Vi (2) Va = Vm + Vp + Vi (3) From equation (2), Vm = C × Va / Cm, Vp = C × Va / Cp, Vi = C × Va / Ci (4) By substituting equation (4) into equation (3) and rearranging, C = 1 / (1 / Cm + 1 / Cp + 1 / Ci) (5) From the equations (2) and (5), the voltage Vp applied to the light emitting layer is as follows: Vp = Cm × Ci × Va / (Cm × Cp + Cp × Ci + Cm × Cp) (6)

The dielectric constant of vacuum is εo, and the relative dielectric constants of the film surface improving layer, the light emitting layer and the insulating layer are εm, εp and εi, respectively.
Since all three capacitors of the same EL element have the same area, the area of Cm, Cp or Ci is S (m ² ), the film surface improving layer, the light emitting layer and the insulating film are dm (m), respectively.
In terms of dp (m) and di (m), from the formula showing the electrical relationship, Cm = εo × εm × S / dm, Cp = εo × εp × S / dp, Ci = εo × εi × S / di ... (7) Substituting equation (7) into equation (6) and rearranging, Vp = dp × εm × εi × Va / (dp × εm × εi + dm × εp × εi + di × εm × εp) (8) Become. By substituting equation (8) into equation (1) and rearranging, dm ≦ (εm × Va) / (εp × Eth) −εm × dp / εp−εm × di / εi (9)

If the thickness dm of the film surface improving layer exceeds the condition of the equation (9), the voltage required for causing the EL element to emit light becomes higher than the designed voltage, and the modulation voltage cannot be obtained. Luminance is reduced, and the EL element does not emit light even when the maximum voltage applied by the drive circuit is applied. The maximum value of the modulation voltage is practically determined by the relationship of the performance of the drive circuit, and is technically possible up to about 250 V at present.

Next, a method of manufacturing a color EL panel according to an embodiment of the present invention will be described in detail with reference to FIG.

First, a sheet thickness of 1.1 mm and a glass size of 1
A glass substrate of 50 mm × 110 mm (1737: manufactured by Corning Japan) or the like is used as the substrate 11, and a transparent conductive film such as ITO is formed on the substrate 11 by various thin film forming methods such as a sputtering method, an electron beam evaporation method, and a spray method. After that, a light-transmissive lower electrode 12 is formed by forming the film into a stripe shape by a photoetching process.

Then, Si ₃ N ₄ / SiO is formed on the lower electrode 12.
_A lower insulating layer 13 was formed by forming a light-transmitting insulating film such as a _two- layered film to a thickness of 200 to 500 nm by, for example, a sputtering method.

Next, the substrate temperature is set to 20 on the lower insulating layer 13.
0-300 ° C, 0.2-0.6 wt% in ZnS
Of Mn added ZnS: Mn pellets as an evaporation source,
A ZnS: Mn layer having a thickness of 300 to 1000 nm was formed by an electron beam evaporation method. The formed ZnS: Mn layer was etched into a stripe pattern orthogonal to the lower electrode 12.

Specifically, on the ZnS: Mn layer, a photoresist (OFPR8600: manufactured by Fuji Film Ohlin Co., Ltd.) was applied by a spin coating method, and was exposed in a predetermined stripe pattern by a photomask and an ultraviolet exposing machine. . After developing with a developing solution (FH2130: manufactured by Fuji Film Ohlin Co., Ltd.) diluted 5 times, the substrate was washed with water. ZnS for 20 seconds at room temperature using 35% hydrochloric acid:
The Mn was etched and washed, and the photoresist was removed with acetone to form striped ZnS: Mn.

Further, the substrate temperature was maintained at 500 to 650 ° C., and a film thickness of 300 to 1000 nm was obtained by electron beam evaporation using SrS: Ce pellets obtained by adding 0.05 to 0.5% by weight of Ce to SrS as an evaporation source. SrS: Ce layer was formed. The formed SrS: Ce layer was etched in a stripe pattern in a portion perpendicular to the lower electrode 12 and without ZnS: Mn.

Specifically, a photoresist (OFPR8600: manufactured by Fuji Film Orin Co.) is applied on the SrS: Ce layer by a spin coating method, and a photomask is used on a layer without ZnS: Mn to expose an ultraviolet light. Exposed to a stripe pattern. After developing with a developing solution (FH2130: manufactured by Fuji Film Ohlin Co., Ltd.) diluted 5 times, the substrate was washed with water. Etch SrS: Ce with 5% phosphoric acid at room temperature for 5 seconds, rinse with water, remove photoresist with acetone, ZnS: Mn
And a light emitting layer 14 in which SrS: Ce was patterned.

Next, a substrate temperature of 20
While maintaining the temperature at 0 to 300 ° C., ZnS having the same crystal structure as ZnS: Mn was formed as the film surface improving layer 15 by electron beam evaporation using ZnS pellets as an evaporation source. The thickness dm of the film surface improving layer 15 was set to satisfy the condition of the expression (9) as described above. For example, in the light emitting layer 14 where ZnS: Mn is patterned, εm = 8 and Va = 20.
0 (V), εp = 8, Eth = 1.0 (MV / cm),
dp = 1 (μm), di = 0.5 (μm) and εi =
In the device manufactured to be 5, dm ≦ (8 × 200) / (8 × 1.0 × 10 ⁶ /1.0×10 ⁻² ) −8 × 1.0 × 1
0 ⁻⁶ /8−8×0.5×10 ^{−6 / 5} dm ≦ 0.2 × 10 ⁻⁶ (m), and the SrS: Ce patterned light emitting layer 14
In the part, εm = 8, Va = 200 (V), εp = 1
0, εth = 0.8 (MV / cm), dp = 1 (μ
m), di = 0.5 (μm), and εi = 5, the element calculated as follows from equation (9) gives dm ≦ 0.4 × 10 ⁻⁶ (m), Since dm is smaller in ZnS: Mn,
In this embodiment, since dm may be 0.2 (μm) or less, the thickness of the film surface improving layer 15 is set to 0.15 μm.

Next, an insulating film such as a SiO ₂ / Si ₃ N ₄ laminated film is formed in the same manner as the lower insulating layer 13, and is sequentially laminated as the upper insulating layer 16.

The substrate on which each layer is formed in this manner is
450-650 ° C in vacuum for improving crystallinity, etc.
Heat treatment was performed for 6 hours.

In the EL element, it is necessary for the charge to flow smoothly in the light emitting layer in order to efficiently emit light with high luminance, and therefore, it is required that the light emitting layer has better crystallinity. As described above, since the film surface improving layer is formed using a material that is close in crystallinity to the light emitting layer, the light emitting layer and the film surface improving layer can be considered as a light emitting layer as a whole. Even if crystal defects are present between such a light emitting layer and a film surface improving layer, the crystal defects can be reduced by heat treatment, so that the flow of charges can be made smooth and the brightness and efficiency of the EL panel can be improved. .

The reason why the heat treatment was performed at 400 ° C. or more was that ZnS: Mn and SrS: Ce used as the light emitting layer material were:
This is because it is known that the crystallinity is sufficiently improved at 400 ° C. or higher as shown in FIG. 5 to improve the luminance.

FIG. 5 shows a color EL according to this embodiment.
Panel annealing temperature of 300 ° C, 350 ° C, 400 ° C
The luminance at L50 of the color EL panel prepared at ℃, 500 ℃ and 650 ℃ is shown. As shown in FIG. 5, the luminance is greatly improved at the annealing temperature of 400 ° C. or higher. When heat treatment is performed at a temperature lower than 400 ° C., the color E having low brightness and efficiency is obtained.
Only L panels can be formed.

Since the upper limit of the heat treatment temperature is set to 650 ° C., which is lower than the deformation and alteration temperature of the glass substrate (1737: manufactured by Corning Japan), deterioration in yield and display quality due to distortion of the substrate and the like are prevented. Will not occur. Since the crystallinity is improved in the light emitting layer 14 and the film surface improving layer 15, the charge flows smoothly,
Brightness and luminous efficiency improved.

Finally, as with the lower electrode 12, ITO is formed to a thickness of 100 to 800 nm by various film forming methods, and then the upper electrode 17 is formed in a stripe shape so as to be orthogonal to the lower electrode 12 by a photoetching process. To form

The EL element 118 thus formed
The light-transmitting electrode is used for the lower electrode 12 and the light-transmitting electrode is also used for the upper electrode 17, and the light extraction direction from the light emitting layer is opposite to that of the conventional monochrome thin-film EL panel. The surface side is the upper direction in FIG. Light from the light-emitting layer 14 in the lower direction in FIG. 1 can be extracted upward when a metal electrode is used or when a reflective material such as an Au-based material is used for the lower electrode 12. The lower electrode 12 needs to have heat resistance to withstand heat treatment. Therefore, refractory metals such as Mo, W and Ta may be used.

The light emitting layer 14 may contain Mg for improving the emission spectrum. ZnS: Tb and SrAl ₂ S ₄ : Eu may be included in the light emitting layer to improve the light emission spectrum of the light emitting layer. There may be more than two types of substances constituting the light emitting layer.

Next, separately from the EL element, a plate thickness of 1.1 m
m on a transparent substrate 111 such as a glass plate, a red filter (CR-7001: manufactured by Fuji Film Ohlin Co., Ltd.) in which a red pigment, a green pigment, and a blue pigment are dispersed in a photosensitive resin, and a green filter ( CG-7001: Fuji Film Ohlin) and blue filter (CB-
7001: manufactured by Fuji Film Ohlin Co., Ltd.), a red, green, and blue color filter 112 having a film thickness of 1.2 μm was sequentially arranged in a stripe shape by photolithography to form a color filter substrate 120. At the time of formation, the green color filter slightly overlaps the red color filter formed earlier, and the blue color filter slightly overlaps the green color filter.
A region in which the color filter to be formed next and the color filter to be formed next were slightly overlapped outside the pixel 216 region was used as the black mask 113.

Next, the light emitting layer 14 and the color filter 112
And so that ZnS: Mn becomes red and green, and SrS: Ce becomes blue.
20 was bonded to an EL element substrate 119 via a resin adhesive 115 (X-9318: manufactured by Mitsui Chemicals, Inc.). Note that X
-9318 is a modified epoxy resin that is fluid and has a low viscosity before curing.

Specifically, on the EL element substrate 119,
20μm diameter plastic beads (Micropearl SP-220: manufactured by Sekisui Fine Chemical Co., Ltd.)
The EL element substrate 119 on which the plastic beads were scattered was bonded to a color filter substrate 120 having a small amount of X-9318 attached to the four corners of the substrate with a toothpick or the like. . Accordingly, the bonding can be performed at a constant distance of 20 μm between the EL element 118 and the color filter 112, which is close enough to avoid the problem of the viewing angle.

Next, the seal plate 18 is attached to the color filter substrate 12 via a seal resin 117 such as an epoxy resin.
0 was attached to the EL element substrate 119 to which the 0 was attached. The sealing plate 18 was prepared in advance by digging one side of a glass plate having a thickness of 1.8 mm to a depth of 0.7 mm using a grindstone, leaving a frame portion, and also providing an injection hole 19.
The substrate on which the EL element substrate 119 on which the color filter substrate 120 was bonded and the seal plate were bonded was placed in a vacuum chamber, and the gap between the EL element substrate 119 and the seal plate 18 was sufficiently evacuated through the injection hole 19.

Injection holes 19 were placed in an insulating liquid 20 composed of silicone oil mixed with 25% by weight of silica gel.
Then, the insulating liquid 20 is leaked from the injection hole 19 by leaking the inside of the vacuum chamber with nitrogen, so that the EL element substrate 119 on which the color filter substrate 120 is bonded.
It was injected into the gap between the sealing plate 18 and the gap between the EL element 118 and the color filter 112. As described above, since the resin adhesive 115 is applied to the four corners of the color filter substrate 120, the EL element substrate 11 is
When the insulating liquid 20 is injected into the gap between 9 and the seal plate 18, the space between the EL element 118 and the color filter 112 is also filled with the insulating liquid 20. However, the silica gel in the silicone oil has a particle size sufficiently smaller than the distance 20 μm between the EL element 118 and the color filter 112, for example, about 5 μm.

After the gap is filled with the insulating liquid 20,
The injection hole 19 was sealed by bonding the sealing plate 110 to the injection hole 19 with an epoxy resin or the like, thereby forming an EL panel substrate 123 as a color EL panel. Insulating liquid 2
0 has a role of protecting the EL element 118 which is extremely weak against moisture.

As described above, according to the embodiment of the present invention, a material having a crystal structure close to that of the light emitting layer material or easily associated with the crystal of the light emitting layer material is used on the entire surface of the light emitting layer where light emission is desired. By forming the film surface improving layer, the continuity of the crystal of the light emitting layer is improved in the patterning portion of the light emitting layer.

Further, the surface of the film surface improving layer formed by various film forming methods such as the vapor deposition method and the sputtering method not including the etching process is more crystalline than the light emitting layer damaged by the etching process and having deteriorated crystallinity. Therefore, between the insulating layer and the film quality improvement layer, a shallow level of charge cannot be formed due to crystal defects, and a deep level of charge is formed, so that the luminance-applied voltage characteristic of the EL element can be steeply maintained. It is possible to prevent an increase in panel power consumption and a decrease in light emission luminance.

Further, the heat treatment improves the interface state between the patterning surface of the light emitting layer of the EL element and the film surface improving layer, and improves the crystallinity at the interface to reduce crystal defects. It is possible to provide a color EL panel with good display quality that can maintain the voltage characteristics steeply and can prevent an increase in panel power consumption and a decrease in light emission luminance.

[0069]

According to the present invention, the continuity of the crystal of the light emitting layer is improved in the patterning portion of the light emitting layer, and a shallow level of charge due to crystal defects is formed between the insulating layer and the film quality improving layer. Since a deep level of electric charge is formed and the luminance-applied voltage characteristic of the EL element can be kept steep, a color EL panel with good display quality that can prevent an increase in panel power consumption and a decrease in light emission luminance can be configured. can do.

According to the present invention, the luminance of a color EL panel can be improved by separating the light emitted from an EL element having a plurality of patterned light emitting layer materials using a color filter, and furthermore, the display quality is good. Color E
It is possible to configure an L panel.

According to the present invention, by setting the film thickness of the film surface improving layer to be equal to or less than a certain film thickness, the voltage necessary for causing the EL element to emit light as in the case where the film thickness exceeds the certain film thickness is reduced to the designed voltage. When the modulation voltage of the driving circuit of the color EL panel is fixed, the luminance is lowered because the modulation voltage cannot be obtained and the EL element does not emit light even when the maximum voltage applied by the driving circuit is applied. No problem.

According to the present invention, the continuity of the crystal of the light emitting layer is improved at the patterning portion of the light emitting layer, and a shallow level of charge due to crystal defects cannot be formed between the insulating layer and the film quality improving layer. Is formed. In addition, the heat treatment improves the interface state between the patterning surface of the light emitting layer of the EL element and the film surface improving layer, and improves the crystallinity at the interface to reduce crystal defects. It is possible to manufacture a color EL panel with good display quality that can be kept steep and prevent an increase in panel power consumption and a decrease in light emission luminance.

According to the present invention, Zn is used as the light emitting layer material.
S: Mn and SrS: Ce, ZnS as a film surface improving layer
And heat treatment at 400 ° C. or higher can provide a color EL panel with high luminance and high luminous efficiency.

According to the present invention, since the heat treatment is performed at a temperature lower than the temperature at which the substrate is deformed and deteriorated, the panel yield is improved and the panel cost is improved without causing the panel deformation during and after the manufacture of the color EL panel. Can be reduced, and deterioration of display quality due to distortion of the panel can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view of a color EL panel according to an embodiment of the present invention.

FIG. 2 is a plan view of the color EL panel of FIG.

FIG. 3 is a graph showing luminance-applied voltage characteristics of an EL element using ZnS: Mn as a light emitting layer using a film surface improving layer.

FIG. 4 is a graph showing luminance-applied voltage characteristics of an EL element having a light emitting layer of ZnS: Mn without a film surface improving layer.

FIG. 5 is a graph showing the luminance of the color EL panel at L50 when the annealing temperature of the color EL panel according to the embodiment of the present invention is 300 to 650 ° C.

[Explanation of symbols]

 Reference Signs List 11 substrate 12 lower electrode 13 partial insulating layer 14 light emitting layer 15 film surface improving layer 16 upper insulating layer 17 upper electrode 111 translucent substrate 112 color filter 113 black mask

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 11/55 CPC C09K 11/55 CPC 11/56 CPC 11/56 CPC H05B 33/12 H05B 33/12 B 33/22 33/22 ZF term (reference) 3K007 AB02 AB03 AB11 AB18 BA06 BB01 BB03 BB05 BB06 CA01 CB01 DA05 DB01 DB02 DC02 DC04 EA02 EC03 FA01 FA02 FA03 4H001 CA05 CC07 XA16 XA30 XA38 YA25 YA58

Claims (6)

[Claims] A substrate, upper and lower electrodes disposed on one surface side of the substrate, two insulating layers disposed between the upper and lower electrodes, and an insulating layer on the substrate side, which is in contact with the insulating layer by etching. A light-emitting layer in which a plurality of light-emitting layer materials are patterned and juxtaposed; a light-emitting layer which is in contact with the light-emitting layer on the light-emitting layer; What is claimed is: 1. A color EL panel comprising: an electroluminescent element including: a film surface improving layer covering a light emitting layer portion to be formed; 2. The color E according to claim 1, further comprising a color filter formed on a light-transmitting substrate, facing the electroluminescent element.
L panel. 3. The film thickness dm (m) of the film surface improving layer is a relative dielectric constant εm of the film surface improving layer and an amplitude value of an applied voltage waveform to start light emission determined by a driving circuit of a color EL panel. Is Va (V), the relative permittivity of the light emitting layer is εp, and the threshold electric field of the light emitting layer at which the light emitting layer starts to emit light is Eth (V /
m), the thickness of the light emitting layer is dp (m), the sum of the thicknesses of the two insulating layers is di (m), and the sum of the apparent dielectric constants of the two insulating layers is εi, dm ≦ (εm × Va) / (εp × Eth) -εm × dp / εp-
2. The color EL panel according to claim 1, wherein the color EL panel is selected so as to satisfy a relationship of [epsilon] m * di / [epsilon] i. 4. A step of forming a lower electrode and an insulating layer on one surface of a substrate; a step of forming a light emitting layer on the insulating layer by patterning a plurality of light emitting layer materials by etching and juxtaposing them; Forming a film surface improving layer on the layer by using a material having good crystallinity compatibility with the light emitting layer material and covering a light emitting layer portion to be made to emit light by a film forming method not including etching; Forming a second insulating layer on the layer and then heat-treating the laminated layer; and forming an upper electrode on the heat-treated insulating layer. Method. 5. The light emitting layer material includes ZnS: Mn and S
rS: Ce is used, and ZnS is used as a material of the film surface improving layer.
Is used, the temperature is set to 4 in the heat treatment step.
5. The method for producing a color EL panel according to claim 4, wherein the temperature is set to 00 ° C. or higher. 6. In the step of heat-treating, the temperature is:
5. The method according to claim 4, wherein the temperature is set lower than the lower one of the deformation temperature and the transformation temperature of the substrate.