KR100611754B1 - Method for fabrication of organic electro luminescence device - Google Patents

Abstract

The present invention deposits ITO used as a transparent electrode in a flat panel display device in a conventional manner such as sputtering, and the transparent electrode is a gas for etching ITO such as Cl ₂ gas, BCl ₃ gas, HBr gas and HI gas. The present invention relates to a method for producing an organic electroluminescent device which improves the roughness of the surface of the ITO such that the surface of the ITO is subjected to surface treatment so that the average roughness of the surface of the ITO is 10 kPa or less.

The method of manufacturing an organic EL device of the present invention comprises the steps of forming a transparent electrode on the substrate; And surface treatment of the transparent electrode using a plasma formed by using at least one of Cl ₂ gas, BCl ₃ gas, HBr gas, and HI gas. .

Therefore, in the method of manufacturing the organic electroluminescent device of the present invention, the surface roughness of the ITO, such as Cl ₂ gas, BCl ₃ gas, HBr gas, and HI gas, is etched, so that the average roughness of the surface of the ITO is 10 kPa or less. This is effective in providing a method of manufacturing an organic EL device having excellent electrical characteristics by solving a defect such as current leakage.

ITO, Roughness, Plasma Surface Treatment

Description

Method for fabricating an organic electroluminescent device {Method for fabrication of organic electro luminescence device}             

1 is a band diagram for a general organic electroluminescent device.

2A and 2B are cross-sectional views of organic electroluminescent devices.

3A and 3B are sectional views of the ITO surface treatment process according to the present invention.

4A to 4C are photographs showing average roughness after ITO formation, after plasma treatment of the present invention, and after conventional wet etching.

 <Description of the symbols for the main parts of the drawings>

302: ITO 303: plasma surface treatment

304: organic light emitting layer

The present invention relates to a method of manufacturing an organic electroluminescent device, and more particularly, the surface of the ITO by plasma surface treatment using a gas for etching ITO, such as Cl ₂ gas, BCl ₃ gas, HBr gas and HI gas, The present invention relates to a method of manufacturing an organic electroluminescent device having excellent electrical properties such that the roughness is 10 kPa or less.

In the flat panel display field, a light crystal and a low power consumption liquid crystal display device have been the most attracting display elements, but since the liquid crystal display is a light receiving element instead of a light emitting element, brightness, Due to technical limitations in contrast, viewing angle, and large area, development of new flat panel display devices that can overcome these disadvantages is being actively developed. Among them, organic electroluminescent devices are receiving the most attention. have.

The organic electroluminescent device is excellent in viewing angle, contrast, etc., compared to a liquid crystal display because it is a self-emission type, and can be light and thin because it does not require an external light source such as a backlight, and is advantageous in terms of power consumption. In addition, since it can be driven by DC low voltage, the response speed is fast, and all the elements constituting the device are solid, they are resistant to external shock, wide use temperature range, and especially inexpensive in terms of manufacturing cost.

In particular, unlike the liquid crystal display device or the plasma display panel (PDP), the deposition and encapsulation process are all performed in the manufacturing process of the organic EL device, and thus, the process is very simple.

On the other hand, the driving method of the organic EL device includes a passive matrix method that does not include a separate thin film transistor in a pixel, and an active matrix method in which a thin film transistor that serves as a switch is formed for each pixel. have.

However, since the passive matrix method has many limitations such as resolution, power consumption, and lifespan, active matrix type organic light emitting display devices are being researched and developed for manufacturing next-generation displays requiring high resolution and large screens.

In the passive matrix method, a scan line and a signal line cross each other to form a device in a matrix form, whereas in the active matrix method, a thin film transistor (ON) is turned on / off. Thin Film Transistor) is located for each pixel, and the thin film transistor serves as a switch to transmit a signal for turning on / off pixel by pixel to a first electrode, and a second electrode facing the first electrode is used as a common electrode. .

FIG. 1 is a diagram illustrating a band diagram of a general organic light emitting display device.

As shown, the organic light emitting device is interposed between an anode 11 and a cathode 12 and the anode and the cathode, and a hole injection layer 13 from the anode layer. ), An organic layer such as a hole transporting layer 14, an emission layer 15, an electron transporting layer 16, an electron injecting layer 17, and the like, are sequentially It consists of. At this time, holes 18 injected into the light emitting layer through the hole injection layer and the hole transport layer from the anode, and electrons 19 injected into the light emitting layer through the electron injection layer and the electron transport layer from the cathode are excitons ( exciton) 20, which emits light corresponding to the energy between the hole and the electron.

The reason why the organic light emitting device is manufactured in a multilayer thin film structure is that the mobility of holes and electrons varies greatly in the case of an organic material. This is because the luminous efficiency is high when the density of holes and electrons is balanced in the light emitting layer.

At this time, when the surface roughness of the ITO formed by the anode is bad, that is, when the roughness is large, a current leakage occurs between the anode and the organic layer or between the anode, the organic layer and the cathode layer, which adversely affects the electrical characteristics of the organic light emitting device. Has the disadvantage of giving.

Accordingly, the present invention is to solve the above-mentioned disadvantages and problems of the prior art, ITO using a transparent electrode ITO by etching the ITO such as Cl ₂ gas, BCl ₃ gas, HBr gas and HI gas, etc. It is an object of the present invention to provide a method for manufacturing an organic electroluminescent device which improves the electrical properties of a display device by improving the roughness of the ITO surface so that the surface of the surface of the surface of the ITO so that the average roughness of the ITO surface is 10 kPa or less.

The object of the present invention is to form a transparent electrode on the formed substrate; And surface-treating the transparent electrode using a plasma formed using any one or more of Cl ₂ gas, BCl ₃ gas, HBr gas, and HI gas.

Details of the above object and technical configuration of the present invention and the effects thereof according to the present invention will be more clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

2A and 2B are cross-sectional views of organic electroluminescent devices.

First, FIG. 2A is a cross-sectional view of a passive organic EL device. As shown in the figure, a transparent electrode 102, which is an anode electrode, is formed on an insulating substrate 101 such as plastic or glass, and not only separates and insulates the transparent electrodes, but also insulates and corrects a step. To form. In this case, the insulating film may be formed first, and the transparent electrode may be formed later. Subsequently, the organic light emitting layer 104 and the cathode 105 are sequentially formed in a direction perpendicular to the direction in which the transparent electrode is formed. In this case, the transparent electrode is generally formed of ITO. In addition, the organic light emitting layer is formed of any one or more of a light emitting layer, a hole injection layer, a hole transport layer, an electron transport layer and an electron injection layer.

In this case, the present invention forms the transparent electrode ITO, and before the organic light emitting layer is formed, the surface of the ITO is treated so that the average roughness is 10 kPa or less. In this case, the reason that the average roughness of the ITO is 10 kW or less is that as described above, the organic light emitting layer is formed on the upper portion of the ITO formed as the anode. In this case, when the average roughness of the ITO increases, leakage current occurs. Since the leakage current adversely affects the electrical characteristics and reliability of the organic light emitting diode, the roughness of the ITO is better. Generally, the roughness of the surface on which leakage current hardly occurs is known to be 10 kW or less.

Next, FIG. 2B is a cross-sectional view of an active organic electroluminescent device. As shown in the figure, a semiconductor layer 202, a gate insulating film 203, a gate electrode 204, an interlayer insulating film 205, and a source / drain including a source / drain region on an insulating substrate 201 such as plastic or glass. A thin film transistor including a drain electrode 206 is formed, and a planarization film 207 formed of an organic film or an inorganic film is formed over the entire surface of the substrate. Subsequently, a predetermined region of the planarization layer is etched to form a contact hole exposing the surface of the source / drain electrode, and an anode 208 which is a transparent electrode such as ITO is formed on the substrate. Subsequently, a PDL layer 209 defining a pixel region of the display element is formed on the substrate, and an organic emission layer 210 is formed on the entire surface of the substrate. Subsequently, a cathode (not shown), which is a common electrode, is formed on the organic emission layer. In this case, the organic light emitting layer may include a light emitting layer, and may further include any one or more layers of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer. In this case, a reflective film (not shown) may be further formed below the anode, which is the transparent electrode, to be used as a top emission organic EL device.

In this case, after forming ITO which is the transparent electrode, the present invention may then surface-treat the ITO or form ITO which is the transparent electrode, and after forming the PDL layer, the ITO may be formed and surface treated. That is, the ITO is surface treated only before the organic light emitting layer is formed on the ITO so that the average roughness is 10 kPa or less.

3A and 3B are sectional views of the surface treatment process of ITO according to the present invention. 3A and 3B are enlarged views of region A of FIG. 2A and region B of FIG. 2B. The application ranges of the two regions form passive and active organic light emitting devices or ITO, which is a transparent electrode, which is the subject of the present invention. After the surface treatment of the surface of the ITO, the process of forming the organic light emitting layer will be described in the same drawing as similar.

First, FIG. 3A is a cross-sectional view of a step of forming ITO on a substrate and performing surface treatment. As shown in the figure, an ITO 302 which is a transparent electrode is formed on the substrate or the planarization layer 301. At this time, the ITO is deposited to a thickness of 200 to 2000 Pa using a sputtering apparatus in a temperature range of 150 to 250 ℃. 4A is a result of measuring the average roughness of ITO formed by the sputtering apparatus, and it can be seen that the average roughness is about 22 GPa.

Subsequently, the surface of the ITO is plasma-treated by an ICP or RIE apparatus using a gas for etching the ITO, such as Cl ₂ gas, BCl ₃ gas, HBr gas, HI gas, or the like, to thereby surface treatment 303.

At this time, as an example of the surface treatment, the surface of the ITO is processed using a process pressure of 0.5 to 1.0 Pa, a source power of 2000 to 3000 W, a bias power of 800 to 1600 W, and a source gas of 80 to 120 sccm using the ICP device. When the surface treatment, as shown in Figure 4b it can be seen that the average roughness has an average roughness of less than 10Å to 5 ~ 8Å, which is the average roughness when surface treatment with a conventional wet etching solution as shown in Figure 4c Not only was worse than the average roughness when first formed at 105 kPa, but the average roughness by the surface treatment according to the present invention was improved by 13 times or more than when the surface was treated with a conventional wet etching solution. can see. At this time, the source gas uses any one or more of Cl ₂ gas, BCl ₃ gas, HBr gas and HI gas.

Accordingly, the present invention uses a plasma apparatus such as RIE or ICP, and passive or active organic electroluminescent device using a source gas which is a gas for etching the ITO such as Cl ₂ gas, BCl ₃ gas, HBr gas and HI gas. By surface-treating ITO, which is a transparent electrode formed on the surface, to have an average roughness of 10 kW or less, a leakage current does not occur between the ITO and the light emitting layer or the ITO and the cathode, and thus an organic electroluminescent device capable of manufacturing an organic electroluminescent device having excellent electrical characteristics. Provided is a method of manufacturing a light emitting device.

The present invention has been shown and described with reference to the preferred embodiments as described above, but is not limited to the above embodiments and those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

Therefore, in the method of manufacturing the organic electroluminescent device of the present invention, the surface roughness of the ITO, such as Cl ₂ gas, BCl ₃ gas, HBr gas, and HI gas, is etched, so that the average roughness of the surface of the ITO is 10 kPa or less. This is effective in providing a method of manufacturing an organic EL device having excellent electrical characteristics by solving a defect such as current leakage.

Claims (12)

Forming a transparent electrode on the substrate; And Surface-treating the transparent electrode using a plasma formed using at least one of Cl ₂ gas, BCl ₃ gas, HBr gas, and HI gas Method for producing an organic electroluminescent device comprising a. The method of claim 1, And an insulating film formed on the substrate to separate, insulate, and correct the step between the transparent electrodes. The method of claim 1, The substrate is formed with a semiconductor layer including a source / drain region, a gate insulating layer, a gate electrode, an interlayer insulating layer, and a planarization layer having contact holes formed therein and a thin film transistor including a source / drain electrode. Method of preparation. The method of claim 3, wherein A method of manufacturing an organic electroluminescent device, characterized in that a reflective film is formed on the planarization layer. The method of claim 3, wherein And a contact hole for electrically connecting the contact hole to the source / drain electrode and the transparent electrode. The method of claim 1, The transparent electrode is a method of manufacturing an organic electroluminescent device, characterized in that ITO. The method of claim 6, The ITO is a method of manufacturing an organic electroluminescent device, characterized in that to deposit a thickness of 200 to 2000 내지 by using a sputtering device in the temperature range of 150 to 250 ℃. The method of claim 1, The plasma manufacturing method of the organic electroluminescent device, characterized in that using the ICP or RIE device. The method of claim 8, The ICP device is characterized in that the transparent electrode is surface treated using process conditions including a process pressure of 0.5 to 1.0 Pa, a source power of 2000 to 3000 W, a bias power of 800 to 1600 W, and a source gas of 80 to 120 sccm. The manufacturing method of the organic electroluminescent element. The method of claim 9, The source gas is a method of manufacturing an organic EL device, characterized in that any one or more of Cl ₂ gas, BCl ₃ gas, HBr gas and HI gas. The method of claim 1, The surface roughness of the transparent electrode after the surface treatment is 10 kPa or less, the manufacturing method of the organic electroluminescent element. The method of claim 1, The surface roughness of the transparent electrode after the surface treatment is 5 to 8 kPa, The manufacturing method of the organic electroluminescent element characterized by the above-mentioned.

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