JP2003163081A - Organic electroluminescent display and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent display, together with its manufacturing method, capable of sufficiently curing an insulating film and a barrier wall at a low temperature while keeping a shape of the barrier wall. <P>SOLUTION: The manufacturing method comprises a step of forming an insulating film 5 and a barrier wall 6 through curing by heating positive photoresists 11b and 11c while irradiating ultraviolet ray in vacuum. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organic electroluminescent display and a method for manufacturing the same.

[0002]

2. Description of the Related Art Organic electroluminescence (Electr
2. Description of the Related Art A Luminescence (EL) display is a display device that forms an image by arranging a plurality of organic electroluminescence (EL) elements on a substrate in a grid pattern and causing each element to emit light as a pixel.

These organic EL devices have a structure in which a single or a plurality of thin films made of an organic material (hereinafter collectively referred to as an organic film) are sandwiched between an anode and a cathode. When a voltage is applied between the anode and the cathode, holes can flow from the anode and electrons can flow from the cathode into the organic film, and the organic film can be excited by the energy generated when the electrons recombine to emit light.

The organic film includes at least a light-emitting layer that emits light when holes and electrons are recombined, and a hole-transporting layer for improving the conductivity of holes from the anode to the light-emitting layer, as well as from the cathode. An electron transport layer for improving electron conductivity may be included in the light emitting layer.

As a method of forming an organic EL display in which a plurality of organic EL elements having the above-mentioned structure as a basic structure are arranged, a plurality of anode lines are first unidirectionally formed on a substrate of the organic EL display. After forming the organic film, a plurality of cathode lines are formed at right angles to the anode line, and finally, the anode, the organic film, and the cathode are sealed with a cover glass to form an organic EL device. There is a way to protect the whole thing.

When the organic EL display is formed as described above, the cross section of the intersection of the anode line and the cathode line includes a structure in which the substrate, the anode, the organic film and the cathode are sequentially laminated. Then, a pixel is formed. Therefore, by selecting a line for the anode and a line for the cathode and applying a voltage, it is possible to cause a pixel where these lines intersect to emit light.

In practice, in order to form a pixel, a grid-like insulating film having holes corresponding to the shape of the pixel is formed on the anode, and an organic film is deposited in the holes of the insulating film. Here, the lattice of the insulating film has a forward tapered shape.

Further, in order to form the cathode not in the entire surface of the substrate but in a line in a direction perpendicular to the anode line, a partition wall for separating the cathode line and the inverse taper-shaped cathode for separating the cathode lines from each other is formed. Need to be formed.

A hard glass substrate is usually used as the substrate of the organic EL display, but it is expected to use a plastic substrate such as a light-weight and flexible film substrate.

[0010]

As the material of the insulating film, an oxide such as SiO ₂ or a photosensitive polyimide resin, or a novolac photoresist is usually used.

In order to pattern the insulating film by using an oxide such as SiO ₂ to form a forward taper shape, it is necessary to use a dry process or the like, which causes a problem that the process becomes complicated.

Further, when a photosensitive polyimide resin is used, a normal taper shape can be easily formed by using a normal photolithography method. However, in order to imidize or polymerize the resin, the temperature of the substrate is Need to be hot. Further, the photosensitive polyimide resin is generally expensive.

Further, when a photoresist is used, it is generally relatively inexpensive and can be easily formed into a forward taper type by using an ordinary lithography method and heat treatment. When the solvent or the like remains, the organic film is adversely affected. Therefore, in order to make the state that does not affect the organic film,
High temperature heat treatment is required.

Further, the partition wall must be formed in a reverse taper shape or an overhang shape in order to completely separate the above-mentioned anode line and cathode line. Usually, a photoresist is used that can form the shape relatively easily. For example, in order to form a reverse taper shape, a novolac negative photoresist is used,
To form the overhang shape, a novolac-based negative photoresist surface-treated with an alkaline solution or monochlorobenzene is used. Even when the barrier ribs are formed using these negative photoresists, high-temperature heat treatment is required to keep the organic film from being affected, and the barrier ribs maintain an inverse taper shape or an overhang shape. It is necessary to select the high temperature heat treatment conditions that can be applied.

There is no problem when a glass substrate is used as an organic EL display substrate as in the prior art, but when a plastic substrate such as a film substrate is used, the heat resistance is low, and thus high temperature heat treatment is required. There is a problem that the manufacturing method of the insulating film and the partition wall by the above-described material and method cannot be used.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing an organic EL display capable of sufficiently curing an insulating film at a low temperature.

Another object of the present invention is to provide an organic EL display capable of sufficiently curing the partition walls at a low temperature and at the same time maintaining the shape of the partition walls, and a method for manufacturing the same.

[0018]

The invention according to claim 1 is
An organic electroluminescent display comprising: a step of forming a first electrode on a substrate; a step of forming an organic film on the first electrode; and a step of forming a second electrode on the organic film. In the manufacturing method,
After performing the step of forming the first electrode, an insulating film made of a positive photoresist is formed on the contour portion of the pixel portion of the display, and the insulating film is heated and simultaneously irradiated with ultraviolet rays in a vacuum. It is characterized by including the step of hardening by.

According to the first aspect of the present invention, after performing the step of forming the first electrode, an insulating film made of a positive photoresist is formed on the contour portion of the pixel portion of the display, and the insulating film is formed. Since the method includes the step of curing the film by simultaneously heating the film and irradiating it with ultraviolet rays in a vacuum, it is possible to provide a method for manufacturing an organic electroluminescent display capable of sufficiently curing the insulating film at a low temperature.

The invention according to claim 2 is the manufacturing method according to claim 1.
In the manufacturing method, the purple per unit volume of the insulating film is
External line irradiation energy is 1 × 10²J / cm³Through 3 × 10⁶J
/cm ³Is characterized in that.

According to the invention of claim 2, the irradiation energy of the ultraviolet rays per unit volume of the insulating film is 1
Since it is from × 10 ² J / cm ^{3 to} 3 × 10 ⁶ J / cm ³ , the insulating film can be sufficiently cured at a low temperature and at the same time the shape of the insulating film can be maintained and the deterioration of the pixel portion can be prevented. Thus, it is possible to obtain an organic EL display having a more appropriate emission life.

According to a third aspect of the present invention, in the manufacturing method according to the first or second aspect, the temperature for heating the insulating film is
It is characterized by being 90 ° C. or higher and 130 ° C. or lower.

According to the third aspect of the present invention, the temperature for heating the insulating film is 90 ° C. or higher and 130 ° C. or lower. Therefore, even if the substrate is made of a material having low heat resistance, the insulating film is sufficiently formed. It is possible to provide a method of manufacturing an organic electroluminescence display that can be cured to a desired temperature and at the same time maintain the shape of the insulating film.

According to a fourth aspect of the present invention, a step of forming a first electrode on the substrate, a step of forming an organic film on the first electrode, and a second electrode on the organic film. In the method for manufacturing an organic electroluminescence display having the step of, at least before performing the step of forming the second electrode, forming a partition wall made of a positive photoresist to separate the second electrode. The method is characterized by including the step of curing the partition wall by simultaneously heating the partition wall and irradiating it with ultraviolet rays in a vacuum.

According to the invention described in claim 4, before performing the step of forming at least the second electrode, a partition wall made of a positive photoresist for separating the second electrode is formed, and the partition wall is formed. Since it includes the step of curing by heating ultraviolet rays and irradiating with ultraviolet rays in a vacuum at the same time,
At the same time as the partition wall can be sufficiently cured at low temperature,
It is possible to provide a method for manufacturing an organic electroluminescence display capable of maintaining the shape of partition walls.

According to a fifth aspect of the present invention, in the manufacturing method according to the fourth aspect, the partition walls are dipped in monochlorobenzene at the time of forming the partition walls to dilute the positive photoresist with an alkaline solution. And a step of forming a layer that is difficult to dissolve in.

According to a fifth aspect of the present invention, the barrier ribs are formed by dipping the positive photoresist in monochlorobenzene at the time of forming the barrier ribs to form a layer on the surface of the positive photoresist that is difficult to dissolve in an alkaline solution. Since the method includes the steps, it is possible to provide a method for manufacturing an organic electroluminescence display in which an overhang-shaped partition wall can be easily formed.

According to a sixth aspect of the invention, in the manufacturing method according to the fourth or fifth aspect, the temperature for heating the partition wall is
It is characterized by being 90 ° C. or higher and 130 ° C. or lower.

According to the invention of claim 6, the temperature for heating the partition wall is 90 ° C. or higher and 130 ° C. or lower.
A substrate of a material having low heat resistance can be used, and the partition wall can be sufficiently cured, and at the same time, a method of manufacturing an organic electroluminescence display capable of maintaining the shape of the partition wall can be provided.

According to a seventh aspect of the present invention, in the organic electroluminescent display having at least an anode, an organic film, a cathode, and a partition wall separating the anode or the cathode, the partition wall is a positive electrode. It is characterized in that it is formed of a mold photoresist.

According to the invention of claim 7, since the partition wall is formed of a positive photoresist, the partition wall can be sufficiently cured at a low temperature and at the same time, the shape of the partition wall can be maintained. An organic electroluminescence display can be provided.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. First, a series of manufacturing steps in the organic EL display will be described. As a method of manufacturing an organic EL display having a pixel portion 10 formed by sequentially laminating an anode 2, an organic film 3 and a cathode 4 on a substrate 1 as shown in FIG. 1, as shown in FIG. First, a plurality of lines of the anode 2 are formed on one side of the substrate 1 in one direction (BB ′ direction in FIG. 2), and the organic film 3 is sandwiched between the lines of the anode 2 and the direction perpendicular to the line (A- There is a method of forming a plurality of lines of the cathode 4 in the A ′ direction) and finally sealing the anode 2, the organic film 3 and the cathode 4 with the cover glass 7.

For convenience of explanation, the case where the anode 2, the organic film 3 and the cathode 4 are laminated in this order on the substrate 1 will be described, but the cathode, the organic film and the anode may be laminated in this order on the substrate. . When the organic EL display is formed as described above, the cross section of the intersection of the line of the anode 2 and the line of the cathode 4 has the substrate 1, the anode 2, the organic film 3, the cathode 4, as shown in FIG. Thus, an organic EL element including a structure in which these are sequentially stacked is formed to form a pixel. Therefore, by selecting the line of the anode 2 and the line of the cathode 4 and applying the voltage,
The pixel portion 10 where those lines intersect can be made to emit light.

In the manufacturing process of the organic EL display as described above, specifically, the substrate 1 is usually washed and the transparent ITO is usually used.
Patterning of the anode 2 such as (Indium Tin Oxide), formation of the insulating film 5, and partition wall 6 for cathode separation
Is formed, pretreatment, film formation of the organic film 3, film formation of the cathode 4, film formation of a protective film, and sealing are performed.

FIG. 3 is a diagram for explaining a series of manufacturing steps of the organic EL display, and FIGS. 3 (a) to 3 (h) are
It is the figure seen from the cross section of the AA 'direction in FIG.
(I) thru | or (k) are the figures seen from the cross section of the BB 'direction in FIG.

First, a plurality of anode 2 lines are formed on the substrate 1. As shown in FIG. 3A, the material of the anode 2 is deposited on the entire surface of the substrate 1. A hard glass substrate is generally used as the substrate 1, but a plastic substrate such as a film substrate can also be used. The material of the anode 2 is, for example, I in consideration of obtaining light emission from the anode 2 side.
A transparent conductive film such as TO is used.

In order to form a plurality of lines of the anode 2 from the ITO film formed on the entire surface of the substrate 1, as shown in FIG.
The steps of photolithography and wet etching shown in (e) are performed. As shown in FIG. 3B, a photoresist film 11a is applied on the entire surface of the transparent conductive film. Next, through the mask 12 having a pattern of a plurality of lines as shown in FIG.
A plurality of line portions for forming the anode 2 in a are shielded from light and ultraviolet rays are irradiated to a portion other than the portion for forming the anode 2.

As shown in FIG. 3D, development is performed to remove unnecessary portions (portions other than the portion where the anode 2 is formed) in the photoresist film 11a. Next, by wet etching, the portion of the transparent conductive film not covered with the photoresist film 11a (the portion other than the anode 2) is dissolved. When the remaining photoresist film 11a is removed, a plurality of transparent conductive film lines remain, and
The anode 2 is formed as shown in (e).

Next, the insulating film 5 for forming the pixel portion 10 is formed. An insulating film material 11b such as a photosensitive polyimide resin or a photoresist is applied to the entire surface of the substrate 1 on which the anode 2 is formed as shown in FIG. Here, similarly to the above, after irradiation with ultraviolet rays through a mask, development is performed. When the insulating film material 11b is a positive photoresist, a lattice-shaped mask is used so that the pixel portion 10 is irradiated with ultraviolet rays and the portion other than the pixel portion 10 is not exposed to ultraviolet rays. Further, the insulating film 5 is cured by being heated at the same time.

Thus, as shown in FIG.
The contour of the pixel portion 10 can be formed by the lattice-shaped insulating film 5 whose cross section in the AA ′ direction in FIG. 2 has a forward tapered shape.

Next, a partition for separating the cathode 4 (hereinafter referred to as a partition for cathode separation) is formed. Figure 3 (h)
As shown in FIG. 4, a cathode separation partition wall photoresist 11c for forming the cathode separation partition wall 6 is applied over the entire surface of the anode 2 and the insulating film 5. Since the lines of the plurality of cathodes 4 are formed in the direction perpendicular to the lines of the anode 2, the partition walls 6 for cathode separation are also formed as the partitions extending in the direction perpendicular to the direction of the lines of the anode 2.

Therefore, for the sake of explanation, the subsequent steps will be described with reference to a direction in which the substrate 1 is inverted by 90 °, that is, a view seen from the BB ′ direction in FIG. Figure 3
(I) is a view seen from a 90 ° right angle direction in the same state as in FIG. 3 (h). Similarly to the above, after irradiation with ultraviolet rays through the mask, development is performed to form partition walls. When the cathode separation partition wall photoresist 11c is a positive photoresist, a mask that shields the portion forming the cathode separation partition wall 6 from light and irradiates the portion other than the partition wall forming portion with ultraviolet light is used. To do.

As a result, as shown in FIG.
A cathode separation partition wall 6 having a reverse taper shape or an overhang shape in a cross section in the BB ′ direction is formed on the insulating film 5. At the same time, the cathode separating partition wall 6 is heated to be sufficiently cured. By the partition wall 6 for cathode separation as described above, the cathode 4 can be formed by being separated into a plurality of lines perpendicular to the line of the anode 2, and each pixel portion 10 can independently emit light. Become.

After the partition wall 6 for cathode separation is formed as described above, the organic film 3 and the cathode 4 are sequentially formed as shown in FIG. 3 (k) (when a protective film is provided, a protective film is further formed). Film formation). Finally, the whole of the pixel portion 10 is covered with the cover glass 7 or the metal plate.

At this time, since the organic EL display is severely deteriorated by oxygen and moisture in the air, moisture and oxygen are removed from the film formation of the organic film 3 and the cathode 4 to the sealing with the cover glass 7 or the metal plate. Therefore, it is performed in a dry nitrogen atmosphere. Further, a chemical adsorption type water absorbing agent 8 (for example, BaO) and an oxygen absorbing agent for removing water and oxygen existing inside the sealed organic EL display are attached to the cover glass 7 or the metal plate.

The cover glass 7 or the metal plate is fixed at the end of the substrate 1 by using the ultraviolet curable resin 9. Regarding the completed organic EL display, A- in FIG.
FIG. 4 shows a schematic cross-sectional view in the A ′ direction and the BB ′ direction.

Next, the method for forming the insulating film in the present invention will be described in detail. IT which is often used as an anode when manufacturing the organic EL display as described above.
When O is normally formed, the side surface is not smooth but rough. When the organic film 3 and the cathode 4 are directly laminated on this ITO, the side surface of the rough ITO breaks the organic film 3 and the ITO that is the anode 2 is formed. Contacts the cathode 4. Therefore, when a voltage is applied, a short circuit occurs and the efficiency of light emission is reduced, or light emission is stopped.

Even if no short circuit occurs,
Since the side surface of the anode 2 forms a strong electric field, the contour portion of the pixel portion 10 corresponding to the side surface of the anode 2 easily emits light, which causes a problem that the pixel portion 10 cannot be uniformly emitted.

Therefore, the pixel portion 10 is formed, a short circuit due to the side surface of the anode 2 having a rough surface is prevented to maintain the light emission efficiency, and the anode 2 and the cathode 4 are insulated around the outline of the pixel to emit light around the pixel. It is necessary to prevent this and to make the pixel portion emit light uniformly. Therefore, the forward tapered insulating film 5 covering the side surface of the ITO is provided.

As a general material for the insulating film 5, SiO is used.
Oxides such as ₂ , a photosensitive polyimide resin, a photoresist, etc. are used. When the insulating film 5 is formed of an oxide such as SiO ₂ , it is necessary to use a dry process or the like for patterning in a forward tapered shape, which complicates the process.

When a photosensitive polyimide resin is used, a normal taper shape can be easily formed by using ordinary photolithography, but the temperature of the substrate 1 is set to 300 in order to imidize or polymerize the resin. It is necessary to raise the temperature to ℃ or higher. In addition, the photosensitive polyimide resin is usually expensive.

Further, when a photoresist is used, the material itself is relatively inexpensive, a forward tapered shape can be easily formed by using ordinary lithography as in the case of the photosensitive polyimide resin, and the temperature required for curing is also high. Although it is not necessary to raise the temperature as high as that of the conductive polyimide resin, it is still necessary to heat at about 200 ° C. or higher for curing in the atmosphere which is usually used.

Such high temperature heating is carried out in the organic EL display in order to prevent generation of water in the photoresist and gas of the residual solvent. For example, heating is performed at 200 ° C. for 60 minutes using a hot plate or the like, and the photoresist is used as the insulating film 5 by such high temperature heating for a long time. The heating temperature is 160 ℃
It is confirmed that the insulating film 5 is in an uncured state where the solvent and the like remain in the photoresist because the insulating film 5 is dissolved in the solvent at about 180 ° to 180 ° and is deformed when the high temperature heat treatment is performed again.

As described above, in order to form the insulating film 5 by curing the oxide such as SiO ₂ or the like, the photosensitive polyimide resin, or the novolac-based photoresist in the atmosphere, it is necessary to heat at a high temperature. If the substrate 1 is a glass substrate, it is possible to use these materials and methods because it has a high heat resistance, but it is not possible to use a substrate having a low heat resistance such as a plastic substrate such as a film substrate.

In the present invention, a positive type photoresist is used for forming the insulating film 5, and curing is performed by irradiating ultraviolet rays in a vacuum in addition to heating, thereby forming a forward tapered shape even at a low temperature of 130 ° C. or lower. The photoresist could be completely cured. That is, after curing the photoresist, the formed insulating film 5 does not dissolve in a solvent such as isoamyl acetate, and is not deformed even when the high temperature heat treatment is performed again, and moisture or solvent gas remaining in the photoresist is removed. It was confirmed that it was not released.

This is the same characteristic as that of the conventional insulating film cured by heating at 200 ° C. for 60 minutes in the air using a hot plate. Here, the temperature for heating the positive photoresist for forming the insulating film 5 when irradiating ultraviolet rays in vacuum is preferably 90 ° C. or higher and 130 ° C. or lower. If the heating temperature is lower than 90 ° C., the photoresist cannot be sufficiently cured even if it is irradiated with ultraviolet rays in a vacuum. If the heating temperature is higher than 130 ° C,
When the heat resistance of the substrate is low, the substrate deteriorates due to high temperature and cannot be used.

For curing the photoresist, a vacuum UV curing device was used which heats the sample 21 on the table 22 as shown in FIG. 5 to a certain temperature while applying a vacuum to irradiate it with ultraviolet rays for a certain period of time. The insulating film 5 is irradiated with ultraviolet rays in a nitrogen atmosphere, not in a vacuum, at 130 ° C.
When heated at a low temperature of about 300 ° C., the surface of the photoresist was only cured, and a temperature of 150 ° C. or higher was required to completely cure the interior of the photoresist.

Here, the vacuum UV curing device will be briefly described with reference to FIG. In the vacuum UV curing device, the sample 21 is placed on a vertically movable table 22 and heated, and at the same time, ultraviolet rays emitted from a UV lamp 23 are emitted. The ultraviolet irradiation is started and ended by opening and closing the shutter 26. The reflector 24 is installed to improve the irradiation efficiency of ultraviolet rays, and the illuminance of the ultraviolet rays with which the sample 21 is irradiated can be detected by the illuminance monitor 27. Further, a heat exhaust device 25 is installed to keep the internal temperature constant.

As described above, the positive type photoresist 13
In the case of curing by UV irradiation in a vacuum at a low temperature of 0 ° C. or lower, it is desirable that the UV irradiation amount satisfy the following expression.

[0060] 1 x 10²J / cm³  <E <3 × 10⁶  J / cm³ Here, E in the above equation is a positive type photoresist for forming the insulating film 5.
Energy of ultraviolet rays irradiated per unit volume of gyst
Represents E = Illuminance of ultraviolet rays irradiated (mW / cm^Two) × irradiation time
(Sec) x irradiation area (cm ²) / Photo for the irradiated insulating film
Resist volume (cm³) Given in.

When the value of E is smaller than the lower limit of the above equation,
The amount of ultraviolet irradiation is insufficient and the photoresist film cannot be sufficiently cured. If the value of E exceeds the upper limit of the above equation, since heating is performed at the same time as ultraviolet irradiation, the heating time becomes too long and the light emitting portion deteriorates, and the light emission life of the organic EL display becomes short.

Furthermore, 5 x 10^Four  J / cm³  <E <1 x 10⁶  J / cm³ And in this case photoresist
The UV irradiation time and heating time of the film are appropriate,
The resist film is sufficiently hardened, and the light emission life is more appropriate.
The organic EL display of is obtained.

As described above, by irradiating the positive photoresist with ultraviolet rays in a vacuum, the heating temperature required for curing the photoresist can be lowered as compared with the conventional case. Therefore, it is possible to manufacture an organic EL display using not only a glass substrate but also a substrate having low heat resistance such as a plastic substrate.

Further, even when the glass substrate is used, the heating time of the photoresist film can be shortened by the method of the present invention. Further, when the pixel portion 10 is formed on the thin film transistor formed on the plastic substrate, the insulating film 5 can be formed by the same method, and a display device can be manufactured without destroying the thin film transistor by high temperature heating. You can

In the present invention, the anode 2 is first formed on the substrate 1.
Although the light is emitted toward the substrate side by patterning, even when the cathode is first patterned on the substrate 1 so that the light is emitted from the side opposite to the substrate 1, the pixel portion 10 of The insulating film 5 can be formed on the contour portion.

Next, the method for forming the partition wall in the present invention will be described in detail. However, here, the pixel portion 10 is shown in FIG.
The cathode separation partition wall 6 for separating the cathode 4 formed on the organic film 3 into a plurality of lines will be described as having the configuration shown in FIG.

The cathode separating partition wall 6 is used in order to accurately separate the cathode 4 into a plurality of lines in the direction perpendicular to the line of the anode 2 by having an inverse taper shape or an overhang shape. When the partition wall 6 for cathode separation is not formed, when the cathode 4 is formed, the cathode 4 is spread over the entire EL display, and it becomes impossible to control light emission for each pixel portion.

In order to form the cathode separating partition wall 6 in the reverse taper shape, a negative photoresist is usually used, and in order to form the overhang shape, the negative photoresist is surface-treated with alkali or chlorobenzene. Is used. However, even when using such a negative photoresist, it is usually necessary to perform high-temperature heating at 200 ° C. or higher in order to obtain a state in which the organic film is not affected. Therefore, it cannot be used when the substrate 1 of the organic EL display is a plastic substrate having low heat resistance.

In the present invention, a positive photoresist is used for forming the partition wall 6 for cathode separation, and the vacuum UV curing apparatus shown in FIG. 5 is used to cure while heating and irradiating with ultraviolet rays in a vacuum. Even at a temperature of 130 ° C. or lower, it could be completely cured while maintaining the reverse taper shape.
That is, it was confirmed that even if it was immersed in the solvent isoamyl acetate for about 10 minutes, it did not dissolve and that it did not deform at all even when placed on a hot plate at 200 ° C. This is the same characteristic as the partition wall 6 for cathode separation formed by curing by heating at 200 ° C. for 60 minutes in the atmosphere using a hot plate.

Here, the temperature for heating the photoresist for forming the cathode separating partition wall 6 when it is irradiated with ultraviolet rays in a vacuum is preferably 90 ° C. or higher and 130 ° C. or lower. If the heating temperature is lower than 90 ° C., the photoresist cannot be sufficiently cured even if it is irradiated with ultraviolet rays in a vacuum. If the heating temperature is higher than 130 ° C., the substrate deteriorates due to the high temperature and cannot be used if the substrate has low heat resistance. Even if the same novolac-based positive photoresist is used, the shape of the cathode separation partition 6 is difficult to form when heated at about 130 ° C. in the atmosphere, and it is difficult to form the partition wall 6 for cathode separation.

According to the method of the present invention, the partition wall for the cathode, which is cured by irradiating it with ultraviolet rays in a vacuum using a photoresist, can be a partition wall which is cured at a low temperature of about 130 ° C., and is further immersed in monochlorobenzene. Then, an overhang type partition can be formed.

When the photoresist film is irradiated with ultraviolet rays and then immersed in monochlorobenzene, a layer hardly soluble in an alkali developing solution is formed on the upper surface layer of the photoresist film, and as a result, the photoresist is dissolved in the alkali developing solution during development. Since the velocity is slower at the top of the membrane and faster at the bottom,
An overhang type partition having a wide upper portion and a narrow lower portion can be formed.

In this case, the shape of the partition wall 6 for cathode separation does not change even if it is formed by heating at 90 ° C. for 10 minutes and irradiation with ultraviolet rays, and it does not dissolve in isoamyl acetic acid as a solvent. But it didn't deform. These characteristics are 90
Similar results were obtained when the film was formed under the conditions of heating at 130 ° C. to 130 ° C. for 10 minutes and ultraviolet irradiation.

When the photoresist film used for the insulating film 5 and the cathode separating partition wall 6 is not sufficiently heated and hardened, dark spots grow and the light emitting portion goes from the edge of the pixel toward the center. Area reduction occurs. In particular, when the cathode separating partition wall 6 is not sufficiently heated and hardened, the area of the light emitting portion of the pixel remarkably decreases from the side where the cathode separating partition wall 6 is located toward the center. That is, FIG.
In the pixel portion 10 as shown in (3), the area of the light emitting portion 32 decreases and the area of the non-light emitting portion 33 increases with the passage of time with respect to the initial light emitting portion 31 at the start of light emission, particularly on the side where the partition wall is present.

Such a reduction in the area of the light emitting portion of the pixel is due to the presence of the partition wall 6 for separating the cathode when the organic film 3 and the cathode 4 are formed. This is because the cathode 4 cannot cover the side surface of the organic film 3 close to. That is, when the partition wall 6 for cathode separation is insufficiently cured, the gas in which the water and the solvent remaining in the photoresist are volatilized is discharged from the partition wall and the organic film 3 is removed.
It is conceivable that the light emitting portion area is reduced as a result.

For example, when a conventional negative photoresist is heated on a conventional hot plate at 200 ° C. for 60 minutes to form the partition wall 6 for cathode separation, a water absorbing agent 8 (BaO or the like) is attached to the cover glass 7. If so, there is almost no reduction in the area of the light emitting portion. However, in the case of a negative photoresist, when the partition wall for the cathode is formed by heating at 130 ° C., it does not cure even if it is irradiated with ultraviolet rays in a vacuum, and the area of the light emitting portion of the pixel changes from the side where the partition wall exists. Decrease to.
A positive photoresist according to the present invention is applied at 90 ° C. to 13 ° C.
In the partition wall 6 for cathode separation, which was formed by irradiating ultraviolet rays in vacuum at 0 ° C. for 10 minutes and immersing it in monochlorobenzene, the area of the light emitting portion in the pixel was not reduced.

Further, the positive type photoresist is easy to form a fine pattern with respect to the negative type photoresist, and is suitable for improving the pattern accuracy and therefore for downsizing. In addition, when forming a partition wall, in the case of a negative photoresist, if a reverse taper or an overhang is formed by contact exposure, it is necessary to increase the film thickness (for example, about 2 μm or more) in order to provide contrast of light. However, in the positive type photoresist, since the partition walls having the above-mentioned shape are formed by immersing in the monochlorobenzene, the thickness can be reduced to, for example, about 1 μm or less without depending on the photoresist film thickness.

In the present invention, the anode 2 is first patterned on the substrate 1 so that the light emission direction is the substrate side. However, the cathode 4 is first patterned on the substrate 1 to emit the light from the side opposite to the substrate 1. Even in this case, the partition wall for anode separation in the anode can be formed by the same method.

[0079]

[Example] [Formation of insulating film] A glass substrate on which an ITO film is patterned into a predetermined wiring shape is ultrasonically cleaned using a neutral detergent, an alkaline cleaner, and IPA (isopropyl alcohol), and nitrogen gas is sprayed. It was dried.

After this substrate was pretreated, a novolac-based positive photoresist for an insulating film was applied by spin coating so as to have a film thickness of 1 μm. After the pre-baking, exposure was performed using a photomask so that the ITO edge portion was covered and the pixel portion was formed, and an insulating film was formed by development.

This substrate was vacuum-cured using a vacuum UV curing device.
Substrate temperature 130 ° C in a vacuum of 1 Pa, UV light intensity 32
Irradiation was carried out at mW / cm ² (wavelength 257 nm) for 10 minutes.
After that, α-NPD (bis [N- (1
-Naphthyl) -N-phenyl] benzidine)
m, Alq3 (tris (8-hydroxyquinolinato) aluminum complex) as a light emitting layer having a thickness of 70 nm, and Mg / Ag (10: 1) as a cathode are continuously formed and sealed in a dry nitrogen atmosphere without being exposed to the air. Then, an evaluation element was manufactured.

This device was tested at room temperature of 25 ° C. and 40% RH.
Continuous energization was performed at a current density of 44.4 A / m ² (200 cd / m ² ) to measure the time change of luminance. Similarly, with the UV vacuum curing device, the UV irradiation time was changed to 3 minutes, 5 minutes, and 60 minutes to prepare an evaluation element, and the same measurement was performed. Further, as a comparison, an insulating film was formed by heating and curing on a hot plate at 200 ° C. for 3 minutes and 60 minutes, and an evaluation element was manufactured by the same procedure and the same measurement was performed.

The measurement results are shown in FIG. In FIG. 7, the horizontal axis is l.
The elapsed time of the og scale, and the vertical axis is the relative brightness representing the brightness corresponding to the time with respect to the initial brightness.

An element having an insulating film cured by the UV irradiation time of 10 minutes by the manufacturing method of the present invention has a conventional temperature of 200 ° C.
The device has a relative luminance life that is almost the same as that of an element in which an insulating film is cured by a hot plate for 60 minutes, and is at a level where it can be put to practical use.

Even if the resin is cured at 130 ° C. for 5 minutes by UV, the conventional 20
It is about the same as when it is cured with a hot plate at 0 ° C. for 3 minutes. Even at 130 ° C. and vacuum UV irradiation, if the irradiation time is short at 3 minutes, the light emission life becomes short, indicating that the insulating film is uncured due to insufficient UV irradiation time. The irradiation time is 60
When exposed for a long time as in the case of minutes, it is considered that the light emitting element deteriorates due to heating for a long time.

[Formation of Partition Walls for Cathode Separation] The glass substrate on which the ITO film is patterned into a predetermined wiring shape is ultrasonically cleaned using a neutral detergent, an alkaline cleaning material, and IPA, and dried by spraying nitrogen gas. It was

After pretreating this substrate, a positive photoresist for an insulating film was applied by a spin coating method so as to have a film thickness of 1 μm. After prebaking, exposure was performed using a photomask so that the ITO edge portion was covered and the pixel portion was formed, and an insulating film was formed by development.

This insulating film was heated and cured on a hot plate at 200 ° C. for 60 minutes, and then a novolac-based positive photoresist for partition was spun to a film thickness of 1 μm in order to prepare a partition for cathode separation. It was applied by the coating method. After pre-baking, it was immersed in a monochlorobenzene solution for a predetermined time to form a layer insoluble in an alkali developing solution on the photoresist surface. Then, the above-mentioned substrate was exposed using a photomask for forming partition walls and developed to obtain overhang-shaped partition walls.

Using a vacuum UV curing device, this substrate was prepared.
Substrate temperature 130 ° C in a vacuum of 1 Pa, UV light intensity 32
Irradiation was carried out at mW / cm ² (wavelength 257 nm) for 10 minutes.
Then, α-NPD is 30 nm as a hole transport layer, Alq3 is 70 nm as a light emitting layer, and Mg / Ag is a cathode.
(10: 1) was continuously formed into a film, and sealing was performed in a dry nitrogen atmosphere without exposing it to the atmosphere to manufacture an evaluation element.

This device was stored in a constant temperature bath at 85 ° C., and changes in the light emitting area were confirmed. For comparison, an evaluation element was prepared by the same procedure using a substrate obtained by heating and curing the negative photoresist for partition walls on a hot plate at 200 ° C. for 60 minutes, and the evaluation was performed under the same conditions.

The measurement results are shown in FIG. FIG. 8 is a graph in which the horizontal axis represents the time elapsed from the start of light emission, and the vertical axis represents the light emitting portion area of the elapsed time with respect to the light emitting portion (initial light emitting portion) area at the start of light emission in percentage.

Under the conventional conditions, a negative photoresist is used for the barrier ribs and the photoresist is cured by a hot plate at 200 ° C. for 60 minutes without being irradiated with ultraviolet rays, and when a positive photoresist is used for the barrier ribs and vacuum ultraviolet irradiation is performed at 130 ° C. When it was cured in 10 minutes and immersed in monochlorobenzene, there was almost no reduction in the area of the light emitting portion. Therefore, in the device formed by using the method of the present invention, the photoresist is sufficiently cured by irradiation with vacuum ultraviolet light even at a low temperature of 130 ° C.
The same life as that cured with a 0 ° C hot plate was observed.

Regarding the negative type photoresist, 1
It was shown that the area of the light emitting portion was drastically reduced with time even after vacuum UV treatment at 30 ° C., the device had a short life, and the photoresist was not cured.

The partition walls formed by irradiating with vacuum ultraviolet rays using a positive photoresist and immersing them in monochlorobenzene have a temperature of 90 to 13 when the ultraviolet irradiation time is 10 minutes.
Similar results were obtained in the 0 ° C range.

The present invention is not limited to the wavelength of ultraviolet rays of 257 nm used in the vacuum UV treatment of the insulating film and the barrier ribs of the present invention, but is applicable to all wavelengths in the ultraviolet region, but preferably, It is desirable to use wavelengths below 380 nm.

[0096]

According to the present invention, it is possible to provide a method for manufacturing an organic EL display in which an insulating film can be sufficiently cured at a low temperature.

Further, it is possible to provide an organic EL display capable of sufficiently curing the partition wall at a low temperature and at the same time maintaining the shape of the partition wall, and a manufacturing method thereof.

[0098]

[Brief description of drawings]

FIG. 1 is a sectional view of a pixel portion of an organic electroluminescence display.

FIG. 2 is a plan view of an organic electroluminescent display.

FIG. 3 is a diagram illustrating a series of manufacturing steps of an organic electroluminescence display.

4A and 4B are schematic views showing the structure of an organic electroluminescence display, in which FIG. 4A is a sectional view taken along the line AA ′ and FIG. 4B is a sectional view taken along the line BB ′.

FIG. 5 is a cross-sectional view of a vacuum UV curing device used in the manufacturing process of the present invention.

FIG. 6 is a diagram illustrating a reduction in the area of a light emitting portion in a pixel when the partition wall for cathode separation is insufficiently cured.

FIG. 7 is a graph of relative luminance change between a light emitting device having an insulating film formed by the method of the present invention and a light emitting device having an insulating film formed by a conventional method.

FIG. 8 is a graph showing a change in a light emitting portion area ratio between a light emitting device having a cathode separating partition formed by the method of the present invention and a light emitting device having a cathode separating partition for comparison.

[Explanation of symbols]

1 substrate 2 anode 3 organic film 4 cathode 5 insulating film 6 Cathode separating partition 7 cover glass 8 Water absorbing agent 9 UV curable resin 10 pixel part 11a Photoresist film 11b Photoresist for insulating film 11c Photoresist for partition wall for cathode separation 12 masks 13 UV 21 samples 22 tables 23 UV lamp 24 Reflector 25 Heat exhaust system 26 shutters 27 Illuminance monitor 31 Initial light emitting part 32 Light emitting part 33 Non-light emitting part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor, Ono             1601 Sakai, Atsugi, Kanagawa Mitsumi Electric Co., Ltd.             Company Atsugi Office F term (reference) 3K007 AB11 AB18 BA06 DB03 EA00                       FA01                 5C094 AA31 AA43 AA49 BA27 CA19                       DA13 DB01 FA01 FA02 FB01                       FB15 FB20                 5G435 AA14 AA17 BB05 CC09 HH14                       KK07

Claims (7)

[Claims] 1. A step of forming a first electrode on a substrate, a step of forming an organic film on the first electrode,
A step of forming a second electrode on the organic film, and a method of manufacturing an organic electroluminescent display comprising: a step of forming the first electrode; A method of manufacturing, comprising the steps of forming an insulating film made of a mold photoresist and heating the insulating film to simultaneously cure the insulating film by irradiating it with ultraviolet rays in a vacuum. 2. The irradiation energy of the ultraviolet rays per unit volume of the insulating film is 1 × 10 ² J / cm ^{3 to} 3 × 10 ⁶ J.
The process according to claim 1, wherein the a / cm ^3. 3. The temperature for heating the insulating film is 90 ° C. or higher and 130 ° C. or lower.
The manufacturing method described. 4. A step of forming a first electrode on a substrate, a step of forming an organic film on the first electrode,
A step of forming a second electrode on the organic film, and a method of manufacturing an organic electroluminescent display having a step of forming at least the second electrode, consisting of a positive photoresist, A manufacturing method comprising: forming a partition wall separating the second electrode, and heating the partition wall to simultaneously cure the partition wall by irradiating ultraviolet rays in a vacuum. 5. The partition wall includes a step of immersing the positive photoresist in monochlorobenzene at the time of forming the partition wall to form a layer insoluble in an alkaline solution on the surface of the positive photoresist. Claim 4
The manufacturing method described. 6. The manufacturing method according to claim 4, wherein a temperature for heating the partition wall is 90 ° C. or higher and 130 ° C. or lower. 7. At least an anode above the substrate, an organic film, a cathode, and a partition wall separating the anode or the cathode,
In the organic electroluminescence display having: the partition wall, the partition wall is formed of a positive photoresist.