KR20040065503A - Method for formation of indium-tin oxide film - Google Patents

Abstract

PURPOSE: A method is provided to achieve improved luminance and lengthen the useful life of display device by enhancing the surface roughness of a conductive metal oxide. CONSTITUTION: A method comprises a step of forming an indium-tin-oxide transparent conductive film into an amorphous state on a substrate; and a step of crystallizing the indium-tin-oxide transparent conductive film by heat treating the indium-tin-oxide transparent conductive film. The formation of the indium-tin-oxide transparent conductive film into an amorphous state is performed by a sputtering process using an indium-tin-oxide target at an ordinary temperature to the temperature of 150 Deg.C.

Description

METHOD FOR FORMATION OF INDIUM-TIN OXIDE FILM}

The present invention relates to a method for forming an indium tin oxide (ITO) transparent conductive film and a transparent conductive laminate formed thereby, and in particular, excellent surface roughness in a polycrystalline state by high temperature heat treatment of an ITO film coated in an amorphous state. A method of obtaining a transparent conductive film.

BACKGROUND OF THE INVENTION Organic electroluminescent display devices are the next generation video display devices used in portable terminals, car navigation systems (CNS), display panels for game machines, laptops and wall-mounted televisions. In the light emitting device, many inorganic materials are used. In recent years, the most widely used light emitting devices include light emitting diodes (LEDs), semiconductor laser diodes, and inorganic light emitting devices used as backlights of liquid crystal displays.

The EL element made of the above inorganic material has problems such as high driving voltage, difficulty in full colorization, and high cost of peripheral driving circuits. An organic light emitting device for solving such a problem is a device in which a light emitting region is an organic material, and an element that transmits a current to the organic material and converts its electrical energy into light energy is called an organic light emitting device.

In general, as shown in FIG. 1, an inorganic oxide layer 11 and a transparent conductive anode 12 are deposited as a thin film on a glass substrate 10, and then a hole transport layer 13 is disposed on the glass substrate 10. ), The light emitting layer 14 and the electron transport layer 15 are sequentially stacked, and finally, the metal electrodes 16 and 17 are vacuum deposited to form a cathode (−). In the organic light emitting display device having the above configuration, when a positive voltage is applied to the positive electrode and a negative voltage is applied to the negative electrode, holes are injected into the positive electrode and electrons are injected into the negative electrode. The injected holes and electrons generate light by recombination of electrons and holes in the organic thin film layer through the hole transport layer and the electron transport layer, respectively. In addition, the anode is used as an electrode for driving the organic light emitting display device and also serves as a hole injection.

The positive electrode, which is a transparent conductive film, includes metal thin films such as gold (Au), silver (Ag), and palladium (Pd), oxide semiconductor thin films such as indium oxide, tin oxide, and zinc oxide, and multilayer thin films by laminating metal oxides and metals. have. Metal thin films have the disadvantage of excellent conductivity but poor optical properties such as transmittance, and oxide semiconductor thin films have low conductivity but good optical properties such as transmittance. The item for evaluating the transparent conductive film largely evaluates the characteristics of the thin film through reliability evaluation of electrical conductivity, transmittance, surface roughness, acid resistance, and moisture resistance.

The method of forming a transparent conductive film electrode includes sputtering, ion plating, and e-beam evaporation, and the electrical and optical characteristics of the transparent conductive film are different from each other. The roughness becomes 3 nm or more on the basis of root mean square (RMS), and thus, spikes are formed during the subsequent process, resulting in uneven emission luminance and inferior emission characteristics. The surface structure of the conventional anode electrode is shown in FIGS. 2A, 2B and 3 as AFM and SEM images, respectively.

The organic light emitting display device is particularly related to the surface roughness. If the surface roughness is poor, projections such as spikes are formed to cause leakage current, thereby degrading device characteristics. Needed.

In general, a method of obtaining a transparent conductive film having excellent surface roughness has a process of improving the surface roughness by forming a conductive metal oxide thin film and then polishing the transparent conductive film (Japanese Patent Laid-Open No. 9-120890). There is a problem in that a residual problem occurs and the device characteristics are lowered to lower the luminance of light. Recently, many methods for improving the surface roughness during the formation of the transparent conductive film without the polishing process have been developed (Japanese Patent Laid-Open No. 10-204960), and there is a method called ion-plating. It is known to have excellent surface roughness because it is deposited with a high energy by a method in which a plasma is made into a beam state and the evaporation of the source of evaporation is performed by directly hitting the source of the evaporation element. In addition, there is indium zinc oxide (IZO), but the surface roughness is excellent, but electrical conductivity is inferior.

Therefore, an object of the present invention is to improve the surface roughness of the conductive metal oxide in order to solve the imbalance of the light emitted when manufacturing the organic light emitting display device to form a transparent conductive film to enable the organic light emitting display device to emit light uniformly. To provide.

In order to achieve the above object, in the present invention, when forming an initial ITO thin film, the film is formed at a low temperature to maintain an amorphous state, and then subjected to high temperature heat treatment to polycrystallize while maintaining excellent surface roughness characteristics in an amorphous state, thereby achieving electrical conductivity and transmittance characteristics of the film. To improve.

1 is a view showing a vertical structure of a conventional organic light emitting display device,

2A and 2B are AFM images of the surface of an ITO transparent conductive film of a conventional organic light emitting display device,

3 is an SEM image of the surface of an ITO transparent conductive film of a conventional organic light emitting display device,

4 and 5 are graphs showing a change in specific resistance and a change in transmittance according to heat treatment time of the ITO film formed according to Examples 2 to 7,

6A and 6B are AFM images after 300 ° C. heat treatment of an ITO film formed according to Examples 2-7,

7 and 8 are SEM photographs after 300 ° C. heat treatment of an ITO film formed at room temperature and 100 ° C., respectively, according to the present invention.

9 to 11 are graphs showing the results of the resistivity and transmittance characteristics of the ITO membrane formed according to Examples 12 to 24.

* Names of the main parts of the drawings *

10: glass substrate 11: inorganic oxide layer

12: anode electrode 13: hole transport layer

14 light emitting layer 15 electron transport layer

16: cathode electrode 17: metal auxiliary electrode

According to the invention,

Optionally forming an inorganic oxide or inorganic nitride layer on the substrate and forming an ITO transparent conductive film thereon in an amorphous state; And

Heat-treating the ITO transparent conductive film to polycrystalline

It provides a method for forming an ITO transparent conductive film comprising a.

The present invention also provides an ITO transparent conductive film obtained by the above method and a light emitting device including the same.

Hereinafter, the present invention will be described in more detail.

The ITO transparent conductive film of the present invention is manufactured by the following method.

(1) inorganic layer forming step

First, an inorganic oxide layer or an inorganic nitride layer may be optionally formed on a substrate such as a glass substrate. In general, inorganic oxides such as SiO ₂ , Nb ₂ O ₅ , TiO ₂ , and inorganic nitrides such as Si ₃ N ₄ are frequently used. Of these, SiO ₂ is the most suitable material because of its high film formation speed. Soda-lime glass or an alkali-free glass substrate is used as the glass substrate, and the inorganic oxides or inorganic nitrides are activated in the high temperature process of forming the ITO transparent conductive film and the Na ions implanted during the formation of the soda lime glass are used as the ITO transparent conductive film It serves to suppress the phenomenon of diffusion. In the alkali free glass substrate, since there is no alkali ion in which a diffusion phenomenon occurs, formation of an inorganic oxide layer is not necessary.

(2) forming an amorphous ITO film

Subsequently, an ITO transparent conductive film is formed on the substrate in an amorphous state. The method for forming an ITO transparent conductive film according to the present invention includes sputtering, E-beam evaporation, and chemical vapor deposition. ), Ion-plating (ion-plating) method and the like are used, of which sputtering method is preferred. In the sputtering method, a DC reactive magnetron sputtering method is used, but an inert gas such as argon is used as a discharge gas for forming plasma, and oxygen is used as a reaction gas.

In general, when sputtered at a high temperature, the crystalline phase is generated and the surface roughness is very poor, it is very important to maintain the amorphous form of the initially formed ITO thin film as described above. Since the temperature at which the transparent conductive film starts to crystallize is usually about 150 ° C., in the present invention, the amorphous ITO thin film forming step is performed at room temperature to 130 ° C., especially at a temperature below the crystallization temperature, particularly at 100 ° C. or less. desirable.

When the transparent conductive film is formed by the sputtering, the amount of argon is usually 600 to 1000 sccm, but 200 to 400 sccm is appropriate, and the amount of oxygen is 0 (over) to 20 sccm, but 0.1 to 5 sccm, particularly 3 sccm or less is appropriate. . The higher the power, the lower the power is advantageous since the microcrystals may be formed during the initial film formation. The power is preferably 1KW to 30KW, but 2KW to 10KW, especially 8KW or less is appropriate.

(3) crystalline ITO film forming step

Subsequently, the amorphous ITO transparent conductive film formed as described above is subjected to a heat treatment step of crystallizing the polycrystalline material. It is very important to crystallize the ITO transparent conductive film formed into an amorphous phase in the early stage, and thus it is possible to improve the electrical conductivity and transmittance characteristics by polycrystallizing while maintaining the excellent surface roughness characteristics of the amorphous phase.

In the present invention, the heat treatment process is subjected to a relatively high temperature heat treatment, the heat treatment can be carried out continuously or separately from the film forming process, the heat treatment is preferably carried out continuously in the vacuum chamber is formed for the process efficiency.

The heat treatment conditions should be effective in improving the resistivity and crystallinity and should be made under the condition that there is no microcrystal formation. When ITO transparent conductive film is formed by sputtering at high temperature without heat treatment step, desired resistivity and transmittance characteristics can be obtained, but surface roughness and crystal orientation characteristics can be used to fabricate desired organic electroluminescent display devices. There is no.

According to the present invention, by heating the amorphous ITO transparent conductive film at a high temperature of 300 to 350 ° C., it is possible to obtain not only excellent surface roughness and crystal orientation, but also similar resistivity and transmittance characteristics as those of the ITO transparent conductive film formed by sputtering at high temperature. Do.

The heat treatment time may be in the range of 20 minutes to 2 hours, preferably within 1 hour, more preferably within 30 minutes.

In addition, the atmosphere of the heat treatment chamber during heat treatment is also important. In general, the heat treatment atmosphere may be a vacuum atmosphere, a nitrogen atmosphere, an oxygen atmosphere, an argon atmosphere, or the like, and a vacuum or oxygen atmosphere is particularly preferable.

In the present invention, the thickness, specific resistance, and transmittance of the ITO transparent conductive film can be easily adjusted according to the film formation conditions and the heat treatment conditions.

The specific resistance of the ITO film suitable for use as an electrode is preferably 3.0 × 10 ⁻⁴ Ωcm or less, and more preferably 2.5 × 10 ⁻⁴ Ωcm or less. The transmittance varies depending on the thickness of the ITO, but is preferably 80% or more, and the thickness of the ITO is usually about 1,000 to 2,000 Pa.

The ITO transparent conductive film prepared according to the present invention has much better surface roughness characteristics than the ITO transparent conductive film prepared by the conventional sputtering method, has excellent resistivity and transmittance characteristics, and has a dense crystal structure, so that the density of the electron carrier density inside the film is excellent. It is possible to prevent the voltage drop between wirings by increasing the and increasing the electron mobility.

The present invention will be described in more detail with reference to the following Examples, which are not intended to limit the present invention.

Examples 1-11 and Comparative Example 1

After the glass substrate was placed in the sputtering chamber, the glass substrate was evacuated to 1 × 10 ⁻³ Pa, and CO ₂ gas was added using a Si target to form SiO ₂ by reactive sputtering. The actual thickness was about 150Å.

An ITO transparent conductive film was formed on a glass substrate having a silica layer by using an ITO target (In ₂ O ₃ (90 wt%) + SnO ₂ (10 wt%)) by direct current magnetron sputtering. The film formation of the ITO transparent conductive film was performed at two temperature conditions, room temperature and 100 ° C. When the film was formed at 100 ° C., the substrate was heated while being evacuated, and the temperature raising rate of the substrate was maintained at 1 ° C./sec. Thereafter, argon as a discharge gas and oxygen as a reaction gas were injected, and power was supplied with a power of 5 KW to form a discharge plasma. Using the discharged plasma, particles of the ITO target were deposited on the substrate surface.

The formed ITO transparent conductive film was heat-treated in the same chamber. Before the heat treatment, the degree of vacuum was evacuated to 1 × 10 ⁻³ Pa and heat was applied to the substrate. The temperature increase temperature of the board | substrate was hold | maintained at 1 degree-C / sec.

The specific resistance and transmittance of the ITO transparent conductive films obtained in each example were measured, and the crystal structure inside the film was analyzed by X-ray diffraction and Scanning Electron Microscope. AFM (Atomic Force Microscope) was measured to observe the change in surface roughness of the surface. In addition, in order to observe the etching rate of ITO, an etching solution was prepared by mixing nitric acid (HNO ₃ ), hydrochloric acid (HCl), and pure water (deionized water) in a 1: 1: 0.08 weight ratio.

In Examples 1 to 7, the ITO transparent conductive film was formed at room temperature or 100 ° C., and then heat-treated at 300 ° C., respectively, and the heat treatment time was divided into 5 minutes, 10 minutes, 20 minutes, 30 minutes, and 60 minutes, respectively. It was a vacuum atmosphere. Each condition is shown in Table 1 below.

Initial film formation temperature Oxygen-Power (KW) Heat treatment temperature (℃) Heat treatment atmosphere Heat treatment time Example 1 Room temperature 2.5-5 300 ℃ vacuum 0 min Example 2 Room temperature 2.5-5 300 ℃ vacuum 5 minutes Example 3 Room temperature 2.5-5 300 ℃ vacuum 10 minutes Example 4 Room temperature 2.5-5 300 ℃ vacuum 20 minutes Example 5 Room temperature 2.5-5 300 ℃ vacuum 30 minutes Example 6 Room temperature 2.5-5 300 ℃ vacuum 60 minutes Example 7 100 ℃ 2.5-5 300 ℃ vacuum 30 minutes Comparative Example 1 300 ℃ 2.5-5 Heat treatment separately

Specific resistance and transmittance characteristics of the ITO transparent conductive films obtained in Examples 1 to 7 and Comparative Example 1 according to the change in heat treatment time were measured, and the results are shown in Table 2 and FIGS. 4 and 5.

Resistivity Transmittance Example 1 8.51 × 10 ^-4 Ωcm 77.0% Example 2 2.56 × 10 ^-4 Ωcm 87.9% Example 3 2.15 × 10 ^-4 Ωcm 88.9% Example 4 1.97 × 0 ^-4 Ωcm 88.2% Example 5 1.98 × 10 ^-4 Ωcm 88.5% Example 6 1.92 × 10 ^-4 Ωcm 89.9% Example 7 1.99 × 10 ^-4 Ωcm 89.1% Comparative Example 1 1.63 × 10 ^-4 Ωcm 90.2%

As can be seen from these results, as the heat treatment time was increased, the resistivity and transmittance characteristics were improved, and as in Example 4, when the heat treatment time was about 20 minutes, the saturation was more than that time. The specific resistance, which is an item of electrical conductivity, tended to decrease as the heat treatment time increased, but it also appeared to saturate almost 30 minutes after the heat treatment time.

Moreover, as a result of the crystallinity analysis, Examples 2-7 and Comparative Example 1 showed the big difference. The change according to each crystal phase is summarized in Table 3 below.

Crystal direction (222) (400) (222) / (400) (400) / (222) Example 2 137 328 0.418 2.39 Example 3 164 400 0.41 2.43 Example 4 125 400 0.31 3.20 Example 5 144 408 0.35 2.83 Example 6 144 449 0.32 3.12 Example 7 172 458 0.38 2.66 Comparative Example 1 424 240 1.77 0.56

In general, in Comparative Example 1 manufactured by DC power reactive magnetron sputtering in a state in which the substrate temperature was raised to 300 ° C., crystals grew in the (222) direction in the preferred direction, but Examples 2 to 7 which were heat treated gave the (400) direction first. As the crystals grew. In Comparative Example 1, the crystal phases in the (222) direction and the (400) direction were evenly distributed, whereas Examples 2 to 7 which were heat treated were preferentially oriented in the (400) direction while the crystal growth in the (222) direction was much suppressed. Losing results were obtained.

In addition, X-ray diffraction analysis showed that the preferred orientation of crystallinity was much better than that of the comparative example. In the comparative example, the peak ratio of (222) / (400) was about 2, but in the example (222) ) / (400) has a peak ratio of 1 or less and generally 0.5 or less, indicating that the ITO transparent conductive film exhibits strong orientation after heat treatment. It is thought that this is because the grains grow continuously in the same direction as the grains grow in the initial amorphous phase.

X-ray diffraction analysis of the thin film formed at room temperature and the thin film formed at 100 ° C. showed that the crystal growth in the (222) direction was larger in the film formed at 100 ° C. than in the film formed at room temperature. Appeared to be visible. In the end, it can be speculated that the crystal growth by the microcrystals occurred during the initial film formation, and it will have a bad effect on the surface roughness.

From this result, the surface roughness of the ITO transparent conductive film has a significant correlation with the crystallinity, for example, the difference between the height of (222) and the height of (400) for a thin film in which the (222) and (400) directions are mixed. While the surface roughness is deteriorated, the thin film uniaxially oriented in the (400) direction can be seen that the difference in the height according to the direction is reduced relatively to obtain a thin film with excellent surface roughness.

The results can also be confirmed through AFM images or SEM images. Measurement results of the AFMs of Examples 1 to 7 and Comparative Example 1 are shown in Table 4 (in Table 4, R _PV is a surface roughness value expressed as a difference between a peak and a valley, and R _A is an average). Surface roughness value, R _RMS is a square root mean surface roughness value), and AFM images of the ITO film of Examples 2 to 7 are shown in FIGS. 6A and 6B.

R _PV R _A R _RMS Example 1 84Å 7.4Å 4.3Å Example 2 92Å 7.3Å 4.6Å Example 3 98Å 7.5 Å 4.1Å Example 4 148 yen 7.8Å 4.4Å Example 5 106Å 7.3Å 4.2Å Example 6 168 yen 7.9Å 4.8Å Example 7 234 yen 19.3Å 13.2Å Comparative Example 1 306 yen 33.3Å 24.6Å

In addition, the formation of microcrystals on the surface generated during heat treatment was observed through SEM images. FIGS. 7 and 8 are SEM images after heat treatment of the ITO film formed at room temperature and 100 ° C., respectively. In the case of 100 ° C. film formation (Example 7), the number of microcrystals increased. Microcrystals appear to be generated during heat treatment, and the formation of microcrystals has a significant effect on surface roughness. The longer the heat treatment time, the higher the frequency of occurrence of microcrystals and the better the properties of resistivity and transmittance, but adversely affect the surface roughness. The microcrystals were also closely related to the initial deposition temperature. There were many differences in the shape after heat treatment between the film formed at room temperature of Examples 1 to 6 and the thin film formed at 100 ° C. as in Example 7. As a result, when the film was deposited at 100 ° C, polycrystalline was not observed by X-ray diffraction analysis. If the structure has a high crystallization rate after heat treatment was found to be high. As the occurrence of microcrystals increased, Example 7 had poor surface roughness characteristics than Examples 1 to 6, but had better surface roughness characteristics than the comparative example. Therefore, the film formation at room temperature in the process of forming the initial thin film can suppress the generation of microcrystals.

In addition, the etching rate of the ITO transparent conductive films obtained in Examples 1 to 7 and Comparative Example 1 was measured, and is shown in Table 5 below. As a result, when the scanning electron microscope (SEM) image was viewed, a large crystal grain was compared. It was observed that the thin film of Example 1 had a relatively low etching rate and that the thin film of the example having small grains had a considerably fast etching rate. In addition, the degree of polycrystallization is different according to the heat treatment time. It was analyzed that the etching rate is lowered because the crystallization proceeds more than the thin film having the short heat treatment time when the heat treatment time is increased.

Etching speed Example 1 Less than 5 seconds Example 2 Less than 35 seconds Example 3 Less than 40 seconds Example 4 Less than 40 seconds Example 5 Less than 40 seconds Example 6 Less than 40 seconds Example 7 Less than 40 seconds Comparative Example 1 60 seconds

In addition, in Examples 8 to 11, the ITO transparent conductive film was formed at room temperature, and then heat-treated at 300 ° C. for 30 minutes, respectively, and the heat treatment atmospheres were changed to vacuum, nitrogen, oxygen, and argon atmospheres, respectively. Specific resistance and transmittance of the ITO membranes obtained in Examples 8 to 11 were measured, and the results are shown in Table 6 below. The initial ITO transparent conductive film had a specific resistance of 8.51 × 10 ^-4 Ωcm and a transmittance of 77%.

Resistivity Transmittance Etching speed Heat treatment atmosphere Example 8 2.76 × 10 ^-4 Ωcm 89.5% Less than 40 seconds vacuum Example 9 2.25 × 10 ^-4 Ωcm 89.8% Less than 40 seconds Oxygen Example 10 2.50 × 10 ^-4 Ωcm 89.7% Less than 40 seconds nitrogen Example 11 2.48 × 10 ^-4 Ωcm 89.0% Less than 40 seconds argon

It can be seen from Table 6 that the resistivity characteristics are greatly changed depending on the heat treatment atmosphere, but the heat resistance atmosphere has the lowest resistivity of 2.25 × 10 ^-4 Ωcm when the heat treatment is performed in the oxygen atmosphere, and the transmittance is not significantly different depending on the heat treatment atmosphere. Can be. On the other hand, since the polycrystallization by heat treatment, the etching rate was considerably slower than before the heat treatment, but the results were considerably faster than the comparative example.

Examples 12-24 and Comparative Example 2

It was carried out similarly as described in Examples 1 to 7, except that the ITO transparent conductive film was formed at room temperature, and then heat-treated at 300 ° C. or 350 ° C., respectively, and the ITO film was prepared using a vacuum or oxygen atmosphere at this time. Film formation conditions and heat treatment conditions of each ITO transparent conductive film are summarized in Table 7. In addition, Comparative Example 2 is a thin film obtained by depositing an ITO transparent conductive film by DC power reactive magnetron sputtering at 350 ° C.

Film formation temperature Oxygen injection amount (sccm) Power (KW) Heat treatment temperature Heat treatment atmosphere Example 12 Room temperature 2 5 300 ℃ 350 ℃ Vacuum atmosphere oxygen atmosphere Example 13 Room temperature 2.5 3 Example 14 Room temperature 2.5 5 Example 15 Room temperature 2.5 8 Example 16 Room temperature 3 5 Example 17 Room temperature 3 8 Example 18 Room temperature 5 5 Example 19 100 ℃ 2 3 300 ℃ 350 ℃ Vacuum atmosphere oxygen atmosphere Example 20 100 ℃ 2 5 Example 21 100 ℃ 2 8 Example 22 100 ℃ 2.5 5 Example 23 100 ℃ 3 5 Example 24 100 ℃ 5 5 Comparative Example 1 300 ℃ 2.5 5 Heat treatment separately Comparative Example 2 350 ℃ 2.5 5

Specific resistance and transmittance characteristics of the ITO transparent conductive films obtained in Examples 12 to 24 and Comparative Examples 1 and 2 are shown in Table 8, FIGS. 9A and 9B (vacuum atmosphere), FIGS. 10A and 10B (oxygen atmosphere), and FIG. 11A ( Vacuum atmosphere) and 11b (oxygen atmosphere), and Table 8 is a table of changes in specific resistance and transmittance characteristics after an oxygen atmosphere heat treatment at 300 ° C.

Vacuum atmosphere Oxygen atmosphere Resistivity Transmittance Resistivity Transmittance Example 12 2.35 × 10 ^-4 Ωcm 87.3% 2.43 × 10 ^-4 Ωcm 86.6% Example 13 2.39 × 10 ^-4 cm 88.6% 2.34 × 10 ^-4 Ωcm 89.0% Example 14 2.03 × 10 ^-4 Ωcm 88.3% 2.10 × 10 ^-4 Ωcm 88.5% Example 15 2.32 × 10 ^-4 Ωcm 88.7% 2.35 × 10 ^-4 Ωcm 89.0% Example 16 2.06 × 10 ^-4 Ωcm 89.1% 2.19 × 10 ^-4 Ωcm 89.2% Example 17 2.18 × 10 ^-4 Ωcm 89.4% 2.37 × 10 ^-4 Ωcm 89.3% Example 18 2.49 × 10 ^-4 Ωcm 91% 2.28 × 10 ^-4 Ωcm 91.0% Example 19 2.32 × 10 ^-4 Ωcm 87.1% 2.26 × 10 ^-4 Ωcm 87.9% Example 20 2.09 × 10 ^-4 Ωcm 88.1% 2.29 × 10 ^-4 Ωcm 87.9% Example 21 2.34 × 10 ^-4 Ωcm 88.7% 2.20 × 10 ^-4 Ωcm 88.1% Example 22 12.23 × 10 ^-4 Ωcm 88.8% 2.21 × 10 ^-4 Ωcm 86.7% Example 23 2.19 × 10 ^-4 Ωcm 88.9% 3.09 × 10 ^-4 Ωcm 88.6% Example 24 2.58 × 10 ^-4 Ωcm 90.2% 3.21 × 10 ^-4 Ωcm 90.2% Comparative Example 1 1.90 × 10 ^-4 Ωcm 90.2% 1.90 × 10 ^-4 Ωcm 90.2% Comparative Example 2 1.65 × 10 ^-4 Ωcm 90.8% 1.65 × 10 ^-4 Ωcm 90.8%

From the above results, it was observed that the properties of the resistivity changed significantly according to the amount of oxygen injected during the initial ITO film formation. In the form of initial ITO transparent conductive film before heat treatment, it was found that the specific resistance and transmittance characteristics were quite good as the amount of oxygen injected. It was found that the characteristics of the initial thin film were good in many thin films with an oxygen injection amount of 5 sccm, such as in Example 18 and Example 24. However, after heat treatment, the result will be quite different. After the heat treatment, when the oxygen injection amount increased, the transmittance characteristic was very good, but the resistivity characteristic was deteriorated, and the oxygen injection amount was at least at least in the transmittance and resistivity characteristic. In the room temperature deposition examples of Examples 12 to 18, when the oxygen injection amount was about 2.5 sccm, it showed the best characteristics after the heat treatment, and the oxygen injection amount of 100 ° C. up to Examples 18 to 24 was 2 sccm. In case of heat treatment, it showed the best characteristics. As a result, the amount of oxygen injected should be changed according to the initial film forming temperature. The higher the film forming temperature, the smaller the amount of oxygen injected.

Overall, when the results of oxygen and vacuum atmospheres were compared, the transmittance was slightly better during heat treatment in oxygen atmosphere, and considering the specific resistance, it was predominantly changed depending on the initial deposition conditions. When looking at the occurrence of the oxygen atmosphere is appropriate.

In summary, it can be seen that the microcrystals can be adjusted according to the deposition conditions of the ITO transparent conductive film before the heat treatment. The relationship with the flow rate of oxygen at the time of initial film-forming, the relationship with film-forming power, the relationship with the initial film-forming temperature, the relationship with the heat processing atmosphere, and the heat-treatment temperature are understood. Oxygen flow rate is not directly related to surface roughness, but in terms of resistivity and permeability, 2 ~ 2.5sccm level seems to be appropriate, and the relationship with deposition power is as low as possible because crystalline phase occurs as the deposition power increases. It is very important to select an appropriate power because it seems advantageous to form a film and too low power may degrade the resistivity. The relationship with the heat treatment temperature was confirmed that the higher the heat treatment temperature does not improve the resistivity characteristics, and after a certain temperature or more, the resistivity characteristics were worsened again. It is also important to set the proper temperature and it has been found to have a significant correlation with the surface roughness because the frequency of microcrystals varies according to the heat treatment temperature. The relationship with the heat treatment atmosphere seems to be the best in heat treatment in oxygen atmosphere than in general atmosphere, nitrogen and argon atmosphere, and the specific resistance is better when heat treatment in oxygen atmosphere than in vacuum atmosphere. The number of was observed smaller. In addition, when the high temperature heat treatment for the polycrystallization according to the present invention, the heat treatment time was found to be sufficient crystallization is about 20-30 minutes.

In conclusion, according to the present invention, an initial amorphous ITO transparent conductive film was first formed and then heat treated to polycrystallize, thereby making it easy to fabricate an organic light emitting display device, and having excellent surface roughness and specific resistance and transmittance were 300 ° C. and 350. It is possible to obtain an ITO film having a similar level to that of an ITO transparent conductive film prepared by direct-current magnetron sputtering at 占 폚, and oriented in the (400) direction and crystal-grown in an excellent surface roughness direction.

According to the present invention, by adopting a method of first forming an ITO transparent conductive film in an amorphous state at a low temperature and then crystallizing it by high temperature heat treatment, it improves the resistivity and transmittance while maintaining excellent surface roughness characteristics in an amorphous state, thereby directly at high temperature. It is possible to manufacture an ITO film having about 3 times better surface roughness than the formed ITO transparent conductive film and having the same level of resistivity and transmittance. Thus, defects such as black spots or white spots on the film and leakage current are reduced, so that light emission luminance is improved. An improved light emitting device can be provided.

Claims (16)

Forming an indium tin oxide (ITO) transparent conductive film in an amorphous state on the substrate; And Heat-treating the ITO transparent conductive film to crystallize Method for forming an ITO transparent conductive film comprising a. The method of claim 1, Wherein the amorphous film formation is performed by sputtering with an ITO target at a temperature from room temperature to 150 ° C. The method of claim 2, The sputtering process is carried out at a temperature of room temperature to 100 ℃. The method of claim 2, A sputtering process is performed using argon as a discharge gas and oxygen as a reaction gas. The method of claim 4, wherein Method of injecting oxygen in the sputtering process characterized in that the range of 0.1 to 5 sccm. The method of claim 2, Characterized in that it uses 2 to 10 KW of power in the sputtering process. The method of claim 1, Characterized in that the heat treatment is carried out at 300 to 350 ° C. The method of claim 1, Heat treatment for 20 minutes to 1 hour. The method of claim 1, Heat treatment in a vacuum or oxygen atmosphere. The method of claim 1, And forming an inorganic oxide or inorganic nitride layer prior to forming the ITO transparent conductive film. An ITO transparent conductive film formed by the method of any one of claims 1 to 10. The method of claim 11, ITO transparent conductive film characterized by having a specific resistance value of 3.0 × 10 ^-4 Ωcm or less. The method of claim 11, ITO transparent conductive film, characterized in that the transmittance is 80% or more. The method of claim 11, ITO transparent conductive film, characterized in that the (222) / (400) peak ratio of the surface crystal is 1 or less. The method of claim 11, ITO transparent conductive film, characterized in that the surface roughness, R _PV is 80 ~ 300 ~ range, R _A is 7 ~ 30Å range, R _RMS is 4 ~ 20Å range. An organic light emitting display device comprising the ITO transparent conductive film of claim 11 as an anode.