KR100859148B1 - High flatness transparent conductive thin films and its manufacturing method - Google Patents

Abstract

A manufacturing method of a high flatness transparent conductive film is provided to manufacture a transparent conductive film with a flat surface that can be used for organic light emitting diodes through a new process that is a multilayer process method as an inexpensive and general DC-magnetron sputtering method. A manufacturing method of a transparent conductive film used in flat panel displays using DC magnetron sputtering comprises the steps of: forming a first layer on a substrate by magnetron sputtering at a high process pressure of 0.5 to 1.2 Pa under an argon gas atmosphere into which oxygen is not added at room temperature; forming a second layer on the first layer continuously by the magnetron sputtering at a low process pressure of 0.1 to 0.4 Pa under an atmosphere containing 0.4% of oxygen relative to argon at room temperature; and heat-treating a multilayer thin film comprising the first layer and the second layer under the non-reactive gas atmosphere. The heat-treatment step is performed by heat-treating the multilayer thin film at a temperature of 100 to 350 deg.C under a pressure of 10^-3 Pa to 10^-5 Pa. The first layer is formed by forming an ITO thin film with a thickness of 30 to 90 nm in the first layer forming step, and the second layer is formed by forming an ITO(Indium Tin Oxide) thin film with a thickness of 60 to 120 nm in the second layer forming step.

Description

High flatness transparent conductive thin films and its manufacturing method

1 is a flowchart illustrating a film forming process of a transparent conductive film according to the present invention.

2 is a cross-sectional view of the transparent conductive film according to the present invention.

3 is a view showing the surface structure shape of the transparent conductive film according to the present invention.

4 is a view showing the surface structure of the transparent conductive film according to the prior art.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a transparent conductive film used in a flat panel display. In particular, an organic light emitting diode, which is spotlighted as a next-generation display, has a high concentration of current density when the surface roughness of a thin film of a transparent conductive film is high. Black spots are generated and a transparent conductive film having flat surface characteristics is required. Accordingly, the present invention relates to a method for manufacturing a high flat transparent conductive film applicable to an organic light emitting diode (OLED) through process control of a DC-magnetron sputtering device which is used in general among film forming apparatuses.

Recently, as interest in displays increases, development of flat panel displays (FPDs), such as thin and light liquid crystal displays (LCDs), plasma display panels (PDPs), organic light emitting diodes (OLEDs), and the like, is actively increasing.

In particular, organic light emitting diodes (OLEDs) are attracting attention as next-generation flat panel displays due to their advantages such as self-luminous characteristics, low voltage driving, fast response speed, and wide viewing angle. Since the organic light emitting diode (OLED) is a current driving method, charge accumulation occurs on the protrusions on the surface of the transparent conductive film, and sparks easily occur, which may cause defects such as black spots. . In order to manufacture flat transparent conductive films for organic light emitting diodes, ion-assisted-sputtering or ion plating processes have been commonly used.

In conventional thin film fabrication, thin film manufacturing methods using high keV energy cause a lot of damage to the substrate or thin film. Accordingly, an ion assisted deposition method is used in which the energy of a material to be deposited by mounting an ion assist facility is reduced to several eV so as not to damage a substrate or a thin film. Ion assisted vapor deposition impinges an atom or gas with energy on the surface of the substrate while depositing or depositing a metal on the other side of the material, or a mass of gas, atoms or clusters, and energizing itself. It is a film-forming method to vapor-deposit. The ion assisted deposition method with low damage to the substrate or the thin film can implement a flat thin film required by the transparent conductive film for the organic light emitting diode, compared to the general thin film manufacturing method.

Figure 4 shows the surface structure of the transparent conductive film prepared using the ion assisted deposition method as described above, such an ion assisted deposition method can deposit a thin film having a flat surface, but the deposition rate is low, the equipment is high, difficult to large area Because of this, there are many difficulties in applying to mass production.

In addition, another method is a method of finely polishing and planarizing the surface of a thin film manufactured using conventional DC-magnetron sputtering. However, as the new process is added, the investment of equipment and space is required, and thus the price of the final product is increased. It causes a problem of ascension.

In the case of a transparent conductive film having a high surface modification property applied to the organic light emitting diode, the organic material is damaged due to the concentration of the current density, so that a poor black spot is caused, so that a flat surface property is required. Generally, thin films formed by DC-magnetron sputtering have a high surface roughness of Rrms of 1 nm or more and Rpv of 20 nm or more, which is reported to be difficult to use for organic light emitting diodes. The DC-magnetron sputtering method is applied to the large-area substrate due to the low facility cost, stable discharge, excellent controllability, and high film formation speed and mass productivity. There is an advantage that can form a uniform thin film.

Therefore, in order to increase the size of the organic light emitting diode, a low cost and general purpose film forming apparatus such as DC magnetron sputtering is required. Accordingly, the present invention provides a method for producing a transparent conductive film having a flat surface that can be used for an organic light emitting diode through a new process called a multilayer process method as a low-cost and general-purpose DC-magnetron sputtering method.

In order to achieve the above object, according to the present invention, in the transparent conductive film used for a flat panel display using DC magnetron sputtering, magnetron sputtering at a high process pressure of 0.5 to 1.2 Pa in an argon gas atmosphere without oxygen at room temperature The first layer formed on the substrate using the method, and the second layer continuously formed on the first layer using a magnetron sputtering method at a low process pressure of 0.1 to 0.4 Pa in an oxygen gas atmosphere of 0.4% compared to argon at room temperature And a multilayer thin film comprising the first layer and the second layer is formed by heat treatment under a non-reactive gas atmosphere.

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Here, the heat treatment of the multilayer thin film is characterized in that formed by heat treatment at 100 ℃ ~ 350 ℃ under a pressure of 10 ^-3 Pa ~ 10 ^-5 Pa.

The first layer may be an ITO thin film formed to a thickness of 30 to 90 nm, and the second layer may be an ITO thin film formed to a thickness of 60 to 120 nm.

In addition, according to the present invention, in the method of manufacturing a transparent conductive film used for a flat panel display using DC magnetron sputtering, by using the magnetron sputtering method at a high process pressure of 0.5 to 1.2 Pa under oxygen-free argon gas atmosphere at room temperature Forming a second layer on the first layer continuously using the magnetron sputtering method at a low process pressure of 0.1 to 0.4 Pa under an oxygen gas atmosphere of 0.4% compared to argon at room temperature. And a step of heat-treating the multilayer thin film including the first layer and the second layer in a non-reactive gas atmosphere is provided.

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Here, in the heat treatment step, the heat treatment of the multilayer thin film is characterized in that the heat treatment at 100 ℃ ~ 350 ℃ under a pressure of 10 ^-3 Pa ~ 10 ^-5 Pa.

Further, in the forming of the first layer, the first layer is formed by forming an ITO thin film with a thickness of 30 to 90 nm, and in the forming of the second layer, the second layer is formed of 60 to 120 nm. It is characterized by being formed by forming an ITO thin film with a thickness.

Hereinafter, the process of the transparent conductive film according to the present invention will be described in detail with reference to FIGS. 1 and 2.

1 is a flowchart illustrating a film forming process of a transparent conductive film according to the present invention.

The first layer (crystallization inhibiting layer) 2 formed on the substrate 1 is formed by injecting only argon gas at a high process pressure of 0.5 to 1.2 Pa to achieve flat surface roughness, and forming a thickness of 30 to 90 nm thin film at room temperature. do. Since the ITO transparent conductive film is generally known to be amorphous formed below 70 nm, DC-magnetron sputtering minimizes non-uniform crystal growth.

In addition, the high process pressure shortens the mean free path of the deposited particles in the chamber, and thus the thin films continuously deposited are grown at low deposition particle energy. However, the thin film grown in the first layer does not contain an appropriate amount of oxygen gas, which realizes low electrical resistance due to the generation of free electrons due to oxygen deficiency and substitution of tin in the indium position, thereby increasing the electrical resistance of the ITO transparent conductive film. do.

Next, the second layer (low resistance realization layer) formed on the first layer is injected with 0.4% oxygen gas compared to argon at a low process pressure of 0.1 to 0.45 Pa to realize a low resistance thin film. The thickness is 60-120 nm and the two layers combine to form 150 nm. Oxygen gas, which is added to compensate for the low resistance of the thin film formed in the first layer, also serves to promote crystallization of the ITO thin film, thereby increasing the mobility of free electrons, thereby reducing the resistance. In addition, the low process pressure increases the mean free path of particles to be deposited by DC-magnetron sputtering, so that high deposition particle energy minimizes the collision between the deposition particles. The crystallinity becomes high.

The prepared thin film is heat-treated at 100 ° C. to 350 ° C. to crystallize the deposited thin film. Crystallization is accelerated by the heat treatment of the multilayer thin films formed into the first and second layers, and high hole mobility can be obtained, thereby achieving low resistance.

2 is a cross-sectional view of the transparent conductive film of the present invention prepared by the above method. As shown in Fig. 2, a general substrate 1 is formed at the bottom, a crystallization inhibiting layer 2 is formed thereon, and finally a low resistance realization layer is formed.

EXAMPLE

A thin film is deposited on a glass substrate from an ITO (In ₂ O ₃ -90%, SnO ₂ -10%) target with DC power of 1 kW using DC-magnetron sputtering. The glass substrate is at room temperature (25 ° C) and argon gas is injected at 100 sccm at a process pressure of 0.54 Pa. The deposition thickness is controlled to 70 nm to suppress crystallization nucleus growth and to form a first layer for controlling the surface roughness.

100 sccm and 0.4 sccm of argon gas and oxygen gas are respectively injected at a process pressure of 0.25 Pa continuously in the same chamber on the deposited first layer, and a second layer is formed to a thickness of 80 nm.

The formed ITO multilayer thin film is heat-treated at 300 ° C. for 10 min in a heat treatment chamber to prepare an ITO transparent conductive film having a flat surface and low resistance.

Table 1 shows the sheet resistance, Rrms, and Rpv of the ITO transparent conductive film prepared according to the present embodiment and the ITO transparent conductive film prepared by conventional DC-magnetron sputtering. As shown in Table 1, it was confirmed that the ITO transparent conductive film manufactured by the method of the present embodiment was improved in flatness while maintaining a low resistance value compared with the conventional method.

division Sheet resistance (Ω / □) Rrms (nm) Rpv (nm) ITO transparent conductive film prepared according to the embodiment 10.1 0.918 12.091 ITO transparent conductive film manufactured by a conventional method 11.4 1.858 29.206

As described above, according to the present invention, a transparent conductive film having a flat surface usable for an organic light emitting diode can be manufactured by using a multilayer process method using a low cost and general purpose DC-magnetron sputtering method. Can be used for flat panel displays such as plasma display panels and organic light emitting diodes.

Claims (8)

In the transparent conductive film used for flat panel displays using DC magnetron sputtering, A first layer formed on a substrate by using a magnetron sputtering method at a high process pressure of 0.5 to 1.2 Pa under an oxygen-free argon gas atmosphere at room temperature, It comprises a second layer continuously formed on the first layer by using a magnetron sputtering method at a low process pressure of 0.1 ~ 0.4Pa in an oxygen gas atmosphere of 0.4% compared to argon at room temperature, And a multilayer thin film comprising the first layer and the second layer is heat-treated under a non-reactive gas atmosphere. delete The method of claim 1, Heat treatment of the multilayer thin film is a transparent conductive film, characterized in that formed by heat treatment at 100 ℃ ~ 350 ℃ under a pressure of 10 ^-3 Pa ~ 10 ^-5 Pa. The method of claim 1, The first layer is an ITO thin film formed to a thickness of 30 ~ 90nm, The second layer is a transparent conductive film, characterized in that the ITO thin film formed to a thickness of 60 ~ 120nm. In the method of manufacturing a transparent conductive film used for a flat panel display using DC magnetron sputtering, Forming a first layer on a substrate by using a magnetron sputtering method at a high process pressure of 0.5 to 1.2 Pa under an oxygen-free argon gas atmosphere at room temperature; Continuously forming a second layer on the first layer by using a magnetron sputtering method at a low process pressure of 0.1 to 0.4 Pa under an oxygen gas atmosphere of 0.4% of argon at room temperature; And heat-treating the multilayer thin film including the first layer and the second layer under a non-reactive gas atmosphere. delete The method of claim 5, In the heat treatment step, the heat treatment of the multilayer thin film is a transparent conductive film manufacturing method characterized in that the heat treatment at 100 ℃ ~ 350 ℃ under a pressure of 10 ^-3 Pa ~ 10 ^-5 Pa. The method of claim 5, In the step of forming the first layer, the first layer is formed by forming an ITO thin film with a thickness of 30 ~ 90nm, In the forming of the second layer, the second layer is a transparent conductive film manufacturing method, characterized in that formed by forming an ITO thin film with a thickness of 60 ~ 120nm.

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