KR100680181B1 - Transparent conductive thin films and thereof manufacturing method - Google Patents

Abstract

The present invention relates to a transparent conductive thin film and a method for manufacturing the same, comprising: depositing a transparent conductive thin film on a glass or plastic substrate; Generating a plasma at atmospheric pressure with a discharge gas and a cleaning gas supplied with an RF power source, and irradiating the thin film deposited on the substrate to clean the surface; And depositing a carbon thin film on the cleaned thin film by any one of sputtering, ion deposition, and plasma chemical vapor deposition.

According to the present invention, the carbon thin film is deposited on the surface of the transparent conductive thin film by using atmospheric pressure plasma to chemically deposit impurities to have a very flat surface roughness, high light transmittance, and even without leaving a difference in sheet resistance before and after deposition. It is maintained high without lowering the work function value due to the adsorption of provides a great effect to solve the problems such as black spot generation, luminous efficiency, high driving voltage at a glance.

Transparent conductive thin film, ITO, plasma, carbon thin film, deposition

Description

Transparent conductive thin film and its manufacturing method {TRANSPARENT CONDUCTIVE THIN FILMS AND THEREOF MANUFACTURING METHOD}

1 is an exemplary configuration diagram of an apparatus for manufacturing a transparent conductive thin film according to the present invention;

Figure 2 is a cross-sectional photograph of the substrate before and after carbon thin film deposition according to the present invention,

Figure 3 is a surface shape photograph according to the deposition thickness and before and after the carbon thin film deposition according to an embodiment of the present invention,

4 is a graph showing the surface roughness change according to the deposition thickness of the carbon thin film according to the embodiment of the present invention,

5 is a graph showing changes in carbon concentration and binding energy in the carbon thin film according to the deposition thickness of the carbon thin film according to the embodiment of the present invention;

6 is a graph showing the light transmittance according to the deposition thickness of the carbon thin film according to the embodiment of the present invention,

7 is a graph showing a work function value according to the deposition thickness of the carbon thin film according to the embodiment of the present invention.

♧ description of the symbols for the main parts of the drawing ♧

100 .... Upper electrode 110 .... Electrode body

120 .... Chamber 122 .... Gas Supply

124 .... Plasma 200 .... Bottom electrode

300 .... feed roll 400 .... power supply

The present invention relates to a transparent conductive thin film and a method of manufacturing the same, and more particularly, to a transparent conductive thin film improved to be suitable for the electrode device of a display device and a solar cell requiring high light transmittance and excellent electrical properties, and a manufacturing method thereof. will be.

With the recent advance in informatization, the importance of information display devices that can exchange information such as text, voice, and images in real time is accelerating regardless of time and place.

This phenomenon has also changed the mainstream of display devices represented by Cathode Ray Tubes (CRTs), which has increased the proportion of flat panel displays (FPDs), which are ergonomic, environmentally friendly, and highly functional.

Typical flat panel displays include liquid crystal display (LCD), which has the advantages of light weight and thinness, and low power consumption, but it is not a light emitting device but a passive device that requires a separate light source, so brightness, contrast, viewing angle, and large area are increased. Many technical limitations are revealed.

Transparent conductive thin films are emerging as constituent materials of next-generation flat panel display devices that can overcome such limitations.

Transparent Conductive Thin Films are degenerate n-type semiconductors with relatively wide band gap energy (3.55-4.39 eV) because of their high transmission (> 80%) in the visible region (wavelength of about 380-780 nm). in ₂ O _3, SnO may be mentioned _2, ZnO, ITO or the like.

Since the transparent conductive thin film has a relatively low electrical resistivity value (2 × 10 ⁻³ Ω㎝), it is widely used in optoelectronic devices, liquid crystal display devices, solar cells, and other thin film devices. LCD, PDP, OLED (Origanic electroLumine-Scence Display).

However, these transparent conductive thin films are required to improve the product life and the luminance of light emitted. To this end, it is necessary to perform the thin film process at a lower deposition temperature, the surface planarization and the impurity cleaning through the polishing process.

This is because the transparent conductive thin film has a sharp surface roughness and roughness due to the difference in local crystal growth and the remaining organic matter on the surface of the thin film. This is because it causes damage to the organic matter during light emission, thereby causing black spots to cause product defects.

In particular, the larger the work function value of the transparent conductive thin film, the lower the charge injection barrier between the anode and the organic material layer, so that a large number of holes are injected into the light emitting layer, thereby lowering the light emission start voltage. Accordingly, a high work function value is required. However, when a large amount of carbon-based impurities are adsorbed on the surface of the transparent conductive thin film, the work function is reduced, which plays an important role in the operation and performance of the OLED device.

As a result, polishing and impurity cleaning processes for planarizing the surface of the transparent conductive thin film are very important factors for product life and performance.

To this end, conventional cleaning using chemical cleaning, low-pressure plasma, ultraviolet / ozone, etc., but the disadvantage that the cleaning effect is lost due to the adsorption of impurities while the transparent conductive thin film is cleaned and exposed to the air by these methods This was caused.

In particular, when low-pressure plasma is used, the most effective cleaning can be achieved, but expensive vacuum equipment is required separately, and the size of the substrate that can be cleaned is limited due to the size of the vacuum chamber. There were also disadvantages.

The present invention was created in view of the above-described problems of the prior art, and is developed to solve this problem, and by depositing a carbon thin film on a transparent conductive thin film, including ITO thin film, which is excellent in surface roughness and light transmittance while being left in the air for a long time. In this case, the main purpose of the present invention is to provide a transparent conductive thin film having a high luminous luminance, excellent operating characteristics, and a long lifespan, and a method of manufacturing the same, which is maintained without increasing the work function value due to the adsorption of impurities.

The present invention is a process for depositing a transparent conductive thin film on a glass or plastic substrate to achieve the above technical problem; Generating a plasma at atmospheric pressure with a discharge gas and a cleaning gas supplied with an RF power source, and irradiating the thin film deposited on the substrate to clean the surface; The present invention provides a transparent conductive thin film comprising a process of depositing and forming a carbon thin film by any one of sputtering, ion deposition, and plasma chemical vapor deposition on the cleaned thin film surface, and a method of manufacturing the same.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

1 is an exemplary configuration diagram of an apparatus for manufacturing a transparent conductive thin film according to the present invention.

The present invention is a process for depositing a transparent conductive thin film including an ITO thin film of the required thickness on a glass or plastic substrate, and a process of depositing a carbon thin film of a certain thickness to improve its characteristics on the surface of the transparent conductive thin film once again. Is done.

At this time, the transparent conductive thin film is formed by a method such as sputtering, ion deposition, electroplating and chemical vapor deposition, the carbon thin film is formed by a method such as sputtering, ion deposition and plasma chemical vapor deposition.

To this end, a plasma generating apparatus through atmospheric pressure discharge as shown in FIG. 1 may be used.

The atmospheric pressure plasma generator is divided into an upper electrode 100 and a lower electrode 200, and is installed on a transfer line through which the substrate B is transferred.

In this case, the substrate B is disposed to be transferred by the transfer roll 300, and the conductive thin film deposited on the substrate B is disposed to face the upper electrode 100.

That is, the substrate B is disposed to be horizontally moved along the space between the upper electrode 100 and the lower electrode 200.

The upper electrode 100 is embedded in the electrode body 110 and is provided insulated from the dielectric 102.

In addition, the electrode main body 110 has a hollow chamber 120 provided therein, and a gas supply hole 122 is provided above the chamber 120 to supply helium, which is a discharge gas, and oxygen, which is a cleaning gas. The discharge gas supply line (L1) and the cleaning gas supply line (L3) is connected and piped, and also the processing gas supply line (L2) to supply hydrocarbon-based gas such as methane, acetylene, propane as the processing gas for plasma chemical vapor deposition ) Is also added.

In addition, the plasma 120 is formed by applying a voltage to the mixed gas supplied between the upper electrode 100 and the lower electrode 200 through the chamber 120 to discharge atmospheric pressure.

In this case, the discharge gas is not limited to helium, it is possible to use an inert gas, and more preferably, helium and argon are mixed at an appropriate ratio.

The upper electrode 100 and the lower electrode 200 are connected to the power supply 400.

Referring to the thin film manufacturing process according to the present invention using a plasma generating device having such a configuration as follows.

First, a transparent conductive thin film is deposited on a glass or plastic substrate to a required thickness by sputtering, ion deposition, electroplating, or chemical vapor deposition.

Subsequently, the substrate on which the transparent conductive thin film is deposited is transferred to a plasma generator, and the surface of the transparent conductive thin film is cleaned by plasma irradiation under appropriate conditions.

At this time, the total amount of discharge gas may be helium. However, it is very good in terms of the cleaning efficiency that oxygen is added and mixed with this helium by 0.05 to 5%.

This is because it is preferably added in the range of 0.05 to 5% in consideration of the cleaning effect and stability of the discharge plasma. Specifically, when added to 0.05% or less, the cleaning effect is almost insignificant. This is because discharge is impossible.

In addition, a sine wave AC power, pulsed DC power, or RF power may be used as the power supply source 400, which may maximize the cleaning effect through plasma heating while preventing damage to the substrate (panel) during dual plasma cleaning. RF power is most preferred.

In this case, if a voltage is applied through the RF power supply, it is desirable to maintain the power density at 5 to 50 W / cm 2, which is hardly exhibited when the power density is 5 W / cm 2 or less, and 50 W / cm 2. In the above case, it is preferable to maintain the above range value because there is a high possibility that the substrate is damaged by the micro arc.

Furthermore, in the case of the washing time, it is preferable to limit the processing efficiency to 1 to 10 seconds. This is the titration time chosen by the enemy through the experimental results.

Subsequently, the cleaning is completed and at the same time, a carbon thin film having a required thickness is deposited on the surface of the transparent conductive thin film by sputtering, ion deposition, or plasma chemical vapor deposition.

At this time, it is more preferable to perform cleaning and deposition in one facility through the plasma generator. Here, it is preferable to use a hydrocarbon gas as the processing gas for forming the carbon thin film, and the hydrocarbon gas is also added by 0.005 to 5% by the same reason as the reason for limiting the oxygen content added to the above-described discharge gas. Is preferred.

In particular, the carbon thin film has a peak value at a binding energy of C1s of 284 or more on the surface of the transparent conductive thin film manufactured in a conventional manner, and is preferably deposited to a thickness of 20 nm or more.

The reason for this is that a carbon thin film having a peak value of 284 eV or more with a binding energy of C1s must be deposited to a thickness of 20 nm or more to increase the work function value, and the value does not change even when left in the air.

EXAMPLE

In the embodiment of the present invention in order to determine whether the carbon thin film formed through the manufacturing method according to the present invention can sufficiently perform the operating characteristics of the transparent conductive thin film, the surface shape, surface roughness, carbon of the carbon thin film after deposition Changes in concentration and binding energy, light transmittance, sheet resistance, and work function were investigated.

To this end, first, a 150 nm ITO transparent conductive thin film was manufactured by sputtering using an ITO target containing 10% SnO ₂ on a glass substrate. Then, the glass substrate on which the ITO transparent conductive thin film was deposited was transferred to a roll. The plasma generated by discharging at atmospheric pressure while being transferred to 300 was irradiated to the surface of the plasma and washed.

At this time, the plasma generation conditions were helium + oxygen as the discharge gas while maintaining a power density of 5 to 50 W / ㎠ through the RF power source, and the generated discharge plasma was irradiated on the surface of the ITO transparent conductive thin film for 2 seconds to clean it. It was.

Subsequently, a carbon thin film was deposited on the surface of the ITO transparent conductive thin film by 6 nm, 27 nm, and 49 nm thicknesses by supplying 1% methane and 99% helium and applying RF power with a power density of 25 W / cm 2. The photo is shown in Fig. 2 (a) is a cross section of only the ITO transparent conductive thin film deposited before the carbon thin film is deposited, (b) is a cross section of the carbon thin film deposited at 49nm, Figure 3 is a photograph shown to contrast the surface shape (a) is an ITO transparent conductive thin film, (b) a carbon thin film deposited at 6nm, (c) a carbon thin film deposited at 27nm, (d) is 49nm The deposited transparent thin film is shown.

As shown in the photograph of FIG. 3, in the state where the carbon thin film is not deposited, the surface shows a sharp columnar state, but as the thickness of the carbon thin film increases, the surface is flattened.

Furthermore, as a result of examining the change in the Rmax surface roughness according to the thickness of the carbon thin film, as shown in FIG. 4, it was confirmed that the Rmax surface roughness value was significantly lowered as the thickness of the carbon thin film was increased.

On the other hand, as a result of confirming the change in the C1s binding energy in the deposited carbon thin film, it was confirmed that as the thickness increases, the peak value of the C1s binding energy increases.

For example, in contrast to the peak of graphite phase at 284.4 eV and the peak of diamond phase at 285.2 eV, in the present invention, as the deposition time increases, the peak position of C1s in the carbon thin film moves toward the diamond phase. there was.

That is, it was confirmed that the fraction of sp ³ / sp ² moved to the larger side.

In addition, as a result of examining the light transmittance according to the thickness of the carbon thin film, it can be seen that as the carbon thin film is deposited as shown in Fig. 6, the light transmittance is increased in the wavelength region of 400 ~ 550nm, especially as the thickness becomes thicker It was confirmed that the light transmittance was further increased.

For example, it can be seen that the light transmittance is significantly increased from 75% to 91% in the wavelength region of 410 ~ 430nm.

In addition, the surface resistance characteristics were investigated. As shown in Table 1 below, in the case of the ITO transparent conductive thin film only, the sheet resistance was 3.34 Ω / ㎠, but in the case of the ITO transparent conductive thin film as shown in Table 1 even though the carbon thin film was deposited at various thicknesses on the surface thereof. It was confirmed that the surface resistance of the equivalent level with.

          Transparent conductive thin film                 Sheet resistance (Ω / ㎠)       150nm ITO                    33.34       150nm ITO + 6nm Carbon Thin Film                    32.87       150nm ITO + 27nm Carbon Thin Film                    32.98       150nm ITO + 49nm Carbon Thin Film                    32.83

Lastly, as shown in FIG. 7, the work function value of the carbon thin film was investigated, and the work function of the ITO transparent conductive thin film before the carbon thin film deposition was 4.65 eV, but as the deposition time of the carbon thin film was increased, that is, the thickness became thicker. As the work function was increased, it was found that the work function value increased by 0.64 eV to 5.29 eV at 49 nm thickness compared to before treatment.

The carbon film was left in the air for more than 24 hours after deposition and nevertheless exhibited a high work function value.

As a result, it was confirmed that excellent operating characteristics can be obtained by depositing a carbon thin film on a transparent conductive thin film including ITO.

As described in detail above, according to the present invention, a carbon thin film having a constant thickness is chemically deposited on the surface of the transparent conductive thin film by using atmospheric pressure plasma to have a very flat surface roughness, high light transmittance, and a difference in sheet resistance before and after deposition. In addition, even if left in the air for a long time, the work function value is maintained high without lowering it provides a great effect that can simultaneously solve problems such as black spot generation, luminous efficiency, high driving voltage.

Claims (8)

A transparent conductive thin film deposited on a glass or plastic substrate by sputtering, ion deposition, electroplating, or chemical vapor deposition to a certain thickness and widely used in optoelectronic devices, liquid crystal display devices, solar cells, and other thin film devices; A transparent conductive thin film, characterized in that the carbon thin film further formed on the surface of the transparent conductive thin film deposited. The method according to claim 1, The carbon thin film is deposited to a thickness of 20 ~ 49nm, a transparent conductive thin film, characterized in that the binding energy of C1s has a peak value at 284 ~ 287eV. Depositing a transparent conductive thin film on a glass or plastic substrate; A process of cleaning the surface by irradiating a thin film deposited on a substrate by discharging the discharge gas at atmospheric pressure with a discharge gas and a cleaning gas supplied with RF power and supplied with an RF power source; Method of manufacturing a transparent conductive thin film comprising the step of depositing and forming a carbon thin film by any one of the method of sputtering, ion deposition, plasma chemical vapor deposition on the cleaned thin film surface. The method according to claim 3, The cleaning process, A method for producing a transparent conductive thin film, characterized in that helium is used as the discharge gas and 0.05 to 5% oxygen is mixed as the cleaning gas. The method according to claim 3, The cleaning process, A method for manufacturing a transparent conductive thin film, wherein argon or nitrogen is used as the discharge gas. The method according to claim 3, The cleaning process, Transparent conductive thin film manufacturing method characterized in that it is made at a power density of 5 to 50 W / ㎠ through an RF power source. The method according to claim 3, In the case of plasma chemical vapor deposition during the carbon thin film deposition process, Method for producing a transparent conductive thin film, characterized in that any one of a hydrocarbon gas of methane, acetylene, propane as a carbon source gas. The method according to claim 7, The hydrocarbon-based processing gas is a transparent conductive thin film manufacturing method, characterized in that 0.05 to 5% addition to the discharge gas is mixed.

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