KR100606668B1 - method for fabricating Organic Electroluminescent display Device - Google Patents

Abstract

The present invention relates to a method of manufacturing an organic electroluminescent display device, comprising sequentially stacking a first electrode and a buffer layer on a light transmissive substrate, and using a dry etching method using any one of a laser beam, an ion beam, and a plasma having a predetermined wavelength. After removing the buffer layer of the light emitting region, the organic light emitting layer and the second electrode are sequentially stacked on the entire surface including the buffer layer. Then, the step of removing the buffer layer of the light emitting region and the step of stacking the organic light emitting layer and the second electrode are repeated once or several times, and then dry etching using any one of a laser beam, an ion beam, and a plasma having a predetermined wavelength. In this way, the pixelation process is performed such that adjacent pixels are electrically separated from each other by removing all or part of the second electrode and the organic light emitting layer on the buffer layer, thereby simplifying the manufacturing process and improving the reliability of the device.

Dry etching

Description

Method for fabricating Organic Electroluminescent display Device

1, 2 and 3 show an organic EL display element according to the prior art.

4A-4D, 5A-5C, and 6A-6J illustrate an organic EL display device manufacturing process according to the prior art.

7A to 7I are process cross-sectional views showing a process for manufacturing an organic EL display element according to a first embodiment of the present invention.

8A and 8B are views showing the shape of the first electrode of the first embodiment of the present invention.

9A and 9B show a pixelation shape of the first embodiment of the present invention.

10A to 10K are cross-sectional views illustrating a process of manufacturing an organic EL display device according to a second embodiment of the present invention.

Explanation of symbols for main parts of the drawings

101: light transmissive substrate 102: first electrode

103: buffer layer 104a, b, c: organic light emitting layer

105a, b, c: second electrode 106: protective film

107: insulation layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to display devices, and more particularly, to a method of manufacturing organic electroluminescent display devices.

Recently, as the size of the display device increases, the demand for a flat display device having less space occupancy is increasing. As one of such flat display devices, an organic EL display device is attracting attention.

In the organic EL display device, an exciton generated by injecting electrons and holes from an electron injection electrode and a hole injection electrode into the light emitting unit is combined with the injected electrons and holes, respectively, from the excited state to the ground state. It is a device that emits light when it falls, and there is an advantage that it can be driven at a low voltage of about 3 to 20V, and research is being actively conducted.

In addition, the organic EL display element has excellent characteristics such as wide viewing angle, high speed response and high contrast, so it can be used as a pixel of a graphic display, a pixel of a television image display or a surface light source. They are thin, light, and have good color, making them suitable for next-generation flat panel displays.

In fabricating an organic EL display element used for such a purpose, a simple method for forming a pixel is to band the first electrodes 2 onto the light transmissive substrate 1, as shown in Figs. After forming in a stripe shape, the organic light emitting layer 3 is coated on the first electrodes 2 by a vacuum deposition method, and then a shadow mask 5 is used for the first electrodes 2. A method of forming the second electrodes 4 in the form of a band in a vertical direction may be mentioned.

In addition, a method of making fine pixels using the partition wall 6 as shown in FIG. 3 to form a finer second electrode strip is also known.

The above methods are mainly used to make monochrome organic EL display elements, and the method of making full-color organic EL display elements is somewhat more complicated than the method of making monochrome organic EL display elements.

Various methods are also known for implementing a full-color organic EL display element, among which Japanese Patent Application Laid-open No. Hei 8-315981 is known as a method for producing a high efficiency full-color organic EL display element.

This method is a method of separately depositing a material emitting red (R), green (G), blue (B) using a shadow mask as shown in Figure 4a to 4d.

That is, as shown in FIG. 4A, the first electrode 2 strips are formed on the transparent substrate 1, and the partition wall 6 is formed in advance to form the second electrode strips thereon.

In addition, the red mask material 5-1 is used to jump over the three partition walls 6 to form one red emitting material layer 4-1.

Next, as shown in FIGS. 4B and 4C, similar to the method of forming the red light emitting material layer 4-1, the green is moved by one space by one side using other shadow masks 5-2 and 5-3. After forming the light emitting material layer 4-2 and the blue light emitting material layer 4-3, as shown in FIG. 4D, the second electrode 3 is deposited on the front surface to display the full-color organic EL display. Fabricate the device.

However, the pixel formation method using the shadow mask has the following difficulties.

In other words, it is difficult to manufacture a shadow mask having a fine pattern, and the width of the partition wall becomes small, which makes it difficult to align the shadow mask on the partition wall.

Therefore, later methods of forming pixels without using a shadow mask began to appear, which is known from US Pat. No. 5,693,962 and Japanese Patent Laid-Open No. 9-293589.

US Pat. No. 5,693,962 is a method of forming sub-pixels that emit red, green, and blue light, respectively, using photoresist as shown in Figs. 5A-5C.

In more detail, as shown in FIG. 5A, the first electrode 12 is formed on the light transmissive substrate 11, and a dielectric material layer 13 made of an organic material or an inorganic material is deposited thereon.

The photoresist 14-1 is formed on the dielectric material layer 13, and the photoresist 14-1 is patterned to expose the surface of the dielectric material layer 13.

The patterned photoresist 14-1 is masked to form a cavity 15-1 structure, and the exposed dielectric material layer 13 is removed using conventional wet or dry etching techniques.

Subsequently, the red light emitting material layer 16-1 and the second electrode 17-1 are sequentially formed in the cavity 15-1, and the photoresist 14-1 is lifted off. To form a first sub-pixel that emits red light.

As shown in FIGS. 5B and 5C, the second and third sub-emitters emit green and blue light in the same manner as the first sub-pixel formation method using the photoresists 14-2 and 14-3. Form the pixels.

On the other hand, Japanese Patent Laid-Open No. 9-293589 is a method using a resist as in the US patent as shown in Figs. 6A to 6J.

In detail, as illustrated in FIG. 6A, the first electrode 22, the red light emitting material layer 23, the second electrode 24, and the passivation layer 25 are sequentially formed on the light transmissive substrate 21, and FIG. 6B. As shown in Fig. 1, a resist 26 is formed on the protective film 25.

6C, the resist 26 is patterned to form a resist pattern 26a in the red light emitting region. As shown in FIG. 6D, reactive ion etching is performed using the resist pattern 26a as a mask. The protective layer 25, the second electrode 24, and the red light emitting material layer 23 are etched, and then the resist pattern 26a is removed to form subpixels emitting red light.

Subpixels emitting green light are also formed through the process shown in FIGS. 6E to 6G in the same manner, and subpixels emitting blue light are also formed through the process shown in FIGS. 6H to 6J in the same manner. .

However, in the conventional method, the organic light emitting layer, the electrode, and the like are damaged by etching such as various gases generated in the resist or the removal of the resist since the pixelation is performed by using a solvent-containing organic substance such as a resist. There are drawbacks to this.

The resist degrades the reliability of the device and has a fatal effect on the life of the device.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and an object thereof is to provide a method for manufacturing an organic EL display element which can be easily pixelated without using a shadow mask and a resist.

A feature of the method for manufacturing an organic EL display element according to the present invention is a method of manufacturing an organic EL display element comprising a first electrode, an organic light emitting layer made of at least one organic material, and a second electrode, wherein a buffer layer is formed on the first electrode After forming and removing the portion where the subpixels of the buffer layer are to be formed using a dry etching method, the organic light emitting layer and the second electrode are sequentially deposited on the entire buffer layer to pixelate the organic EL display element.

Other features of the present invention include a first step of sequentially forming a first electrode, a buffer layer, an organic light emitting layer made of at least one organic material, and a second electrode on a light-transmissive substrate, and a second electrode and organic material of a predetermined region by dry etching. And a second step of performing pixelation so that adjacent pixels are electrically separated from each other by removing the light emitting layer.

Another feature of the present invention is to use any one of a laser beam, an ion beam, and a plasma during dry etching.

Another feature of the present invention is to perform a flattening process after forming the second electrode when etching using plasma.

Still another feature of the present invention is a buffer layer of a light emitting region by a first step of sequentially stacking a first electrode and a buffer layer on a light transmissive substrate, and a dry etching method using any one of a laser beam, an ion beam, and a plasma having a predetermined wavelength. A second step of removing the second step; a third step of sequentially stacking the organic light emitting layer and the second electrode on the entire surface including the buffer layer; a fourth step of repeating the second step and the third step once or several times; A method of performing pixelation such that adjacent pixels are electrically separated from each other by removing all or part of the second electrode and the organic light emitting layer on the buffer layer by a dry etching method using any one of a laser beam, an ion beam, and a plasma having a wavelength of? It consists of 5 steps.

Referring to the accompanying drawings, a method of manufacturing an organic EL display device according to the present invention having the above characteristics is as follows.

The concept of the present invention is that when manufacturing an organic EL display element having at least two electrodes and an organic light emitting layer composed of a single or a plurality of organic layers formed between the electrodes, instead of using a shadow mask or a resist, instead of a laser beam, ion It is simply pixelation by dry etching using a beam, plasma, or the like.

In actual production of a full-color organic EL display panel, a plurality of R (Red), G (Green), and B (Blue) sub-pixels are formed, but for convenience, each of R, G, and B Only the subpixel manufacturing process will be described.

7A to 7I are cross-sectional views illustrating a process of fabricating an organic EL display device according to the present invention. As shown in FIG. 7A, a first material made of indium tin oxide (ITO) or other transparent conductive material on a light transmissive substrate 101 is illustrated. Electrodes 102 are formed.

Here, the first electrode 102 may be formed in a strip form as shown in FIG. 8A, or may be formed in a delta form as shown in FIG. 8B.

Subsequently, as shown in FIG. 7B, the buffer layer 103 is formed on the entire surface including the first electrodes 102.

In this case, the material used for the buffer layer 103 may be a material having good insulating properties and capable of patterning in a process, and organic or inorganic materials such as photoresist, silicon oxide, and silicon nitride may be used.

In addition, the buffer layer 103 is generally spin coating (dipping), dipping (Dr. Blade) method, thermal evaporation (thermal evaporation) method, e-beam evaporation method, sputtering ( The vapor deposition may be performed by sputtering, chemical vapor deposition, or the like.

As shown in FIG. 7C, the buffer layer 103 of the portion where the red subpixel is to be formed is removed using a dry etching method using a laser beam, an ion beam, a plasma, and the like.

If a monochromatic organic EL display panel is to be manufactured, the buffer layer 103 of the portion where the subpixel (light emitting area) is to be formed is removed as a whole.

The monochromatic organic EL display panel will be described later.

As shown in FIG. 7D, the organic substrate emits red light on the entire surface including the buffer layer 103 after cleaning the substrate through oxygen plasma treatment or UV / ozone cleaning. The light emitting layer 104a and the second electrode 105a are sequentially deposited to form a red subpixel.

For example, the organic light emitting layer 104a is formed by stacking a hole injection layer, a hole transport layer, and a light emitting layer. The hole injection layer is coated with copper phthalocy anine at a thickness of about 10 to 30 nm, and the hole transport layer is about 30 nm to Formed with N, N'-diphenyl-N, N'-bis (3-methylphenyl)-(1,1'-biphenyl) -4,4'-diamine (TPD) having a thickness of 60 nm and emitting layer thereon Silver tris (8-hydroxy-quinolate) aluminum (abbreviated Alq ₃ ) was deposited to a thickness of 40 nm to 60 nm and DCM 2 was used as the dopant.

As the second electrode 105a, any one of Al, Ca, Mg: Ag, and Al: Li is used.

Next, as shown in FIG. 7E, the buffer layer 103 of the portion to be formed by the green subpixel is removed using a dry etching method using a laser beam, an ion beam, a plasma, and the like as in FIG. 7C.

As shown in FIG. 7F, the organic light emitting layer 104b and the second electrode 105b emitting green light are deposited.

Here, for example, Alq ₃ is doped with coumarin 6 as the light emitting material of the organic light emitting layer 104b.

Subsequently, as shown in FIG. 7G, portions to form a blue subpixel are equally removed, and as shown in FIG. 7H, the organic light emitting layer 104c and the second electrode 105c emitting blue light are shown. Deposit.

Here, as the light emitting material of the organic light emitting layer 104c, for example, BAlq ₃ is doped with perylene.

As shown in FIG. 7I, the second electrodes 105a, b, and c on the buffer layer 103 are dry-etched using a laser beam, an ion beam, a plasma, and the like to electrically insulate the sub-pixels. All or part of the organic light emitting layers 104a, b, and c are removed.

Here, in the case where the first electrode has a stripe shape as shown in FIG. 9A, the line separating the laser beam is a straight line, but when the first electrode is in the delta shape as shown in FIG. 9B, the difference is not a straight line. have.

Thereafter, a protective film (moisture absorbing layer, moisture proof layer, etc.) 106 is formed on the entire surface, and then sealed with a shield glass.

In the present invention using the dry etching method as described above, when performing the etching process with a laser beam, at least the device should be carried out in a vacuum or dried inert gas atmosphere to prevent deterioration of the device.

In addition, in consideration of the physicochemical characteristics of the material to be etched from among the various lasers in the infrared to ultraviolet wavelength range, the one having the appropriate wavelength and power is selected and used.

The most important consideration is the absorption wavelength of the material.

Among the lasers, frequency doubled Nd: YAG lasers with green wavelengths or excimer lasers with ultraviolet wavelengths are suitable, and pulse widths are properly adjusted in an average range of several mW to several kW. do.

In the present invention, a pulse laser is more effective than a continuous oscillation laser because the device is easily damaged by thermal degradation when using a continuous oscillation laser.

In contrast, pulsed lasers suffer very little thermal damage because the reaction time with the material to be etched is very short.

The pulse repetition rate of this pulse laser is generally 1 Hz to 10 ¹⁵ Hz.

In addition to such a laser beam, in the case of using a plasma such as reactive ion etching, an additional process is added.

Referring to FIGS. 10A to 10K, since the processes of FIGS. 10A to 10H are the same as those of FIGS. 7A to 7H, detailed descriptions thereof will be omitted.

As shown in FIG. 10I, an insulating layer 107 is formed by spin coating a well planarized electrically insulating organic material on the entire surface including the second electrode 105.

As a result of this planarization, the entire surface including the portion where the buffer layer is etched is of similar height.

Next, as shown in FIG. 10J, when the etching is performed by a reactive ion etching method using plasma, a thin portion of the insulating layer 107 is first etched, and then a part of the second electrode 105 and the organic light emitting layer 104 below it. Or all are removed so that adjacent subpixels can be electrically separated.

On the other hand, a portion where the insulating layer 107 is thick is etched only part or all of the insulating layer 107 during the same time and does not damage the second electrode 105 below it.

At this time, it is important to control the process parameters as the thickness and etching rate of the insulating layer 107 as appropriate.

Then, as shown in FIG. 10K, a protective film (moisture absorbing layer, moisture proof layer, etc.) 106 is formed on the entire surface, and then sealed with a shield glass.

The method of manufacturing a full-color organic EL display element has been described so far, and it is more effective to use the present invention using a laser to produce a monochrome organic EL display element.

That is, the first electrode and the buffer layer are sequentially formed on the light transmissive substrate, and the buffer layer of the portion where the subpixel (light emitting region) is to be formed is removed as a whole by dry etching, and then the organic light emitting layer made of at least one organic material, and the second The process is very simple and fast because the electrodes can be formed sequentially and the device can be pixelated by the dry etching method of the present invention.

The organic EL display element manufacturing method according to the present invention has the following effects.

First, the desired portion can be selectively cut or etched.

Second, it does not use a photolithography process and is not subject to solvents that are lethal to the device.

Third, since the shadow mask and the wet process are not used, the process is simple, the productivity is improved, and the defect rate can be significantly reduced.

Fourth, the etched cross section is clean and the etching depth can be easily adjusted.

Fifth, a wide range of materials that can be etched, fine widths of about 15 μm or less can be etched or cut, and large areas of panels can be processed simply and quickly.

Claims (13)

In the method of manufacturing an organic EL display element comprising a first electrode, an organic light emitting layer made of at least one organic material, and a second electrode, After forming a buffer layer on the first electrode and removing a portion where the subpixels of the buffer layer are to be formed by using a dry etching method, the organic light emitting layer and the second electrode are sequentially deposited on the entire buffer layer to form the organic EL display device. The organic EL display device manufacturing method characterized in that the pixelation. The method of manufacturing an organic EL display element according to claim 1, wherein the dry etching method uses any one of a laser beam, an ion beam, and a plasma. A first step of sequentially forming a first electrode, a buffer layer, an organic light emitting layer made of at least one organic material, and a second electrode on the light transmissive substrate; And a second step of performing pixelation such that adjacent pixels are electrically separated from each other by removing the second electrode and the organic light emitting layer in a predetermined region by a dry etching method. 4. The method for manufacturing an organic EL display element according to claim 3, wherein the dry etching method uses any one of a laser beam, an ion beam, and a plasma. The method of claim 4, wherein when etching using the laser beam, the laser beam has a pulse and a wavelength of the laser beam is determined according to an absorption wavelength of a material to be removed. The method according to claim 4, further comprising the step of performing a planarization process after forming the second electrode when etching using the plasma. The method of manufacturing an organic EL display element according to claim 6, wherein the organic material is spin coated for the planarization process. The method of claim 3, wherein in the second step, And removing adjacent portions of the second electrode and the organic light emitting layer under the second electrode to separate adjacent pixels. 4. A method according to claim 3, wherein the buffer layer is electrically insulating. 4. A method according to claim 3, wherein the buffer layer is formed of any one of photoresist, silicon oxide, and silicon nitride. The method of claim 3, wherein the buffer layer is spin coating, dipping, Dr. blade method, thermal evaporation method, e-beam evaporation method, sputtering method A method of manufacturing an organic EL display element, characterized in that it is formed by any one of a sputtering method and a chemical vapor deposition method. A first step of sequentially stacking a first electrode and a buffer layer on the light transmissive substrate; A second step of removing the buffer layer of the light emitting region by a dry etching method using any one of a laser beam, an ion beam, and a plasma having a predetermined wavelength; A third step of sequentially stacking the organic light emitting layer and the second electrode on the entire surface including the buffer layer; A fourth step of repeating the second step and the third step once or several times; Pixelation is performed such that adjacent pixels are electrically separated from each other by removing all or part of the second electrode and the organic light emitting layer on the buffer layer by a dry etching method using any one of a laser beam, an ion beam, and a plasma having a predetermined wavelength. The organic electroluminescent display element manufacturing method consists of a 5th step which is carried out. 13. The organic EL display device according to claim 12, further comprising the step of performing a planarization process by forming an insulating layer on the entire surface after the fourth step when etching using plasma in the fifth step. Manufacturing method.

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