KR101283686B1 - Thermal Stability Transparent Conductive Thin Film and Method for Preparing Thermal Stability Transparent Conductive Thin Film - Google Patents

Abstract

The present invention relates to a thermally stable transparent conductive film and a method for producing a transparent conductive film. The transparent conductive film according to the present invention is crystallized even by heat treatment at a relatively low temperature by incorporating titanium in the indium oxide and tin oxide, it has a stable specific resistance value can achieve heat stability.

Thermal Stability, Transparent, Conductive Film, Titanium

Description

Thermal Stability Transparent Conductive Thin Film and Method for Preparing Thermal Stability Transparent Conductive Thin Film}

The present invention relates to a thermally stable transparent conductive film and a method for producing a transparent conductive film. More specifically, the present invention relates to a method of manufacturing a thermally stable transparent conductive film and a transparent conductive film which can be crystallized even at a relatively low temperature by adding titanium to indium oxide and tin oxide, and at the same time having a stable resistivity value.

The present invention is derived from a study conducted as part of the IT source technology development project of the Ministry of Knowledge Economy [Task Management Number: 2006-S-079-04, Task name: Smart window using a transparent electronic device].

Conventionally, materials doped with Sn have been studied as a material for transparent conductive films, and in practice, ITO (Indium Tin Oxide) has been widely used.

Conventional methods for depositing such an ITO thin film on a substrate include DC-Magnetron Sputtering, RF-Sputtering, Ion Beam Sputtering, and E-Beam Evaporation. Physical Vapor Deposition), and Chemical Vapor Deposition such as Sol-Gel and Spray Pyrolysis were used.

In particular, DC-magnetron sputtering is a reality that is most applied to the manufacturing of liquid crystal display or plasma display panel by applying to mass production process in the field because high-quality thin film characteristics and continuous work are possible.

For such sputtering, a sintered body obtained by sintering raw material powder is used as a target for sputtering. Particularly, when an oxide film is formed by using a target, a part of oxygen supplied to the film is supplied to the target itself, and only oxygen is insufficient. Since it can provide as a gas, the fluctuation | variation of the amount of oxygen gas in atmospheric gas can be reduced compared with the case of using an alloy target.

As a result, compared with the case of using an alloy target, manufacture of the transparent conductive film which has uniform thickness and a uniform characteristic is more easy. Therefore, the method of using an oxide sintered body as a target is widely adopted industrially.

The ITO thin film needs to be crystallized in order to lower its specific resistance, and therefore it is necessary to form a film at a high temperature or to perform a heat treatment at a high temperature after the film formation.

The manufactured ITO is characterized in that it has a low resistivity value for use at ambient temperature by heat treatment after deposition on a substrate such as glass or plastic. However, the change in the characteristics of the device due to the change in the resistivity has been pointed out as a problem due to the process temperature used when manufacturing the device using the ITO thin film.

Accordingly, a first object of the present invention is to provide a transparent conductive film having a stable specific resistance value according to various types of flat panel display process temperatures and crystallizing even at a relatively low temperature.

In addition, a second object of the present invention is to provide a method for manufacturing a transparent conductive film having a stable specific resistance value according to various kinds of flat panel display process temperatures and which can be formed even at heat treatment at a relatively low temperature.

In order to solve the first problem, the present invention provides a transparent conductive film having excellent thermal stability including a mixture of titanium indium oxide and tin oxide.

In the transparent conductive film according to the present invention, the titanium is preferably in the form of titanium oxide or metal titanium, and the proportion of the metal component in the transparent conductive film is 85 to 90 at% indium, 1 to 5 at% titanium, and the remaining tin. Is preferably.

Moreover, it is preferable that the transmittance | permeability of the said transparent conductive film which concerns on this invention is 80 to 90%, and sheet resistance value is 20-30 ohm * cm <2>.

In order to solve the second problem, the present invention comprises the steps of preparing an indium oxide powder or a rare metal indium powder, tin oxide powder or metal tin powder, and a raw material powder mainly composed of titanium oxide powder or metal titanium powder; Forming a transparent conductive film from the raw material powder using a sputtering device; And it provides a method for producing a transparent conductive film having excellent thermal stability comprising the step of heat-treating the formed transparent conductive film at a temperature of 300 ℃ or less.

In the method for producing a transparent conductive film according to the present invention, it is preferable that the raw material powder has a specific surface area of 8 to 12 m 2 / g, and an average diameter of 0.5 to 1 μm, and the raw material powder is wet-pulverized and dried. Do.

In addition, in the method for manufacturing a transparent conductive film according to the present invention, the step of forming a transparent conductive film using the sputtering apparatus comprises the steps of: heat-treating raw material powders under an inert atmosphere; Forming and sintering the powder into a desired shape to produce a sputtering target; And depositing a transparent conductive film using a sputtering apparatus equipped with the sputtering target. The sintering is preferably carried out at 900 to 1400 ℃ under atmospheric pressure, the target is preferably polished to improve its surface state.

In the method of manufacturing a transparent conductive film according to the present invention, the transparent conductive film is preferably deposited at an initial vacuum of 1 × 10 ⁻⁶ or less using a sputtering apparatus, and the formed transparent conductive film is heat-treated at a temperature of 300 ° C. or less. It is desirable to.

The transparent conductive film according to the present invention can be crystallized in heat treatment at a relatively low temperature by including titanium in the indium oxide and tin oxide, and also has a stable specific resistance value according to various kinds of flat panel display process temperature, thereby ultimately achieving thermal stability. .

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

The transparent conductive film according to the present invention can be crystallized even in the heat treatment at a relatively low temperature by including titanium in the indium oxide and tin oxide, it is possible to improve the thermal stability.

Indium oxide and tin oxide may be used as separate oxides, and ITO (indium tin oxide) may be used, and titanium included in the indium oxide and tin oxide may be titanium oxide or metal titanium. In addition, the +4 tetravalent titanium oxide may be further included in the transparent conductive film according to the present invention. The addition of the + tetravalent titanium is because the ion radius of the + tetravalent titanium is about 30% smaller because the solid solution between the thin film or the mixture of the target can be made more efficient.

In addition, the metal component ratio in the transparent conductive film is preferably present in 85 to 90 at% indium, 1 to 5 at% titanium and the remaining tin. Here, when titanium is present in less than 1 at%, crystallization cannot be achieved, the resistivity value cannot be lowered, and when used in excess of 5 at%, the ionized titanium includes a transparent conductive film containing indium oxide and tin oxide. Scattering occurs at, resulting in high carrier concentration, resulting in reduced mobility and increased resistance.

The transparent conductive film formed by including titanium in the indium oxide and tin oxide has a transmittance of 80 to 90% and a sheet resistance of 20 to 30Ω · cm 2.

The transparent conductive film may be deposited on a substrate through a physical vapor deposition method or a chemical vapor deposition method, and when using a sputtering process of the physical vapor deposition method, a target sintered body is manufactured by using indium oxide, tin oxide, and titanium. It is available.

1A is a flowchart illustrating a process of manufacturing a transparent conductive film according to an embodiment of the present invention, and FIG. 1B is a flowchart illustrating a process of forming a transparent conductive film in a process of manufacturing a transparent conductive film of the present invention.

1A and 1B, a method of manufacturing a transparent conductive film according to the present invention includes a raw material powder mainly composed of indium oxide powder or rare metal indium powder, tin oxide powder or metal tin powder, and titanium oxide powder or metal titanium powder. Preparing (S11); Depositing a transparent conductive film on the raw material powders using a sputtering apparatus (S12); And heat treating the transparent conductive film at a temperature of 300 ° C. or less (S13).

In the step (S11) of preparing an indium oxide powder or a rare metal indium powder, a tin oxide powder or a metal tin powder, and a raw material powder mainly composed of titanium oxide powder or metal titanium powder, specific surface areas of powders used as raw materials are respectively It is preferable to use the thing of 8-12 m <2> / g and average diameter of 0.5-1 micrometer.

In addition, the raw material powder may be obtained by wet grinding a mixture containing zinc oxide powder or rare metal indium powder, tin oxide powder or metal tin powder, and titanium oxide powder or metal titanium powder as a main component, and drying the wet pulverized fine powder. . In this case, the wet grinding is a uniform mixing and grinding using a wet mill, bead mill, ultrasonic wave, or the like, and the drying may be performed by spray drying or a box furnace. Herein, the particle size of the powder may be adjusted according to the density of the sputtering target and the size during grinding.

Subsequently, the forming of the transparent conductive film using the sputtering apparatus of the raw material powders (S12) may include: heat treating the raw material powders under an inert atmosphere (S21); Forming and sintering the powder into a desired shape to produce a target for sputtering (S22); In operation S23, a transparent conductive film is deposited using a sputtering apparatus equipped with the sputtering target.

In the step (S21) of heat treatment in the inert atmosphere, residual moisture on the surface of the powder may be removed by heat treatment at 500 to 800 ° C. for 1 to 12 hours under an inert atmosphere such as nitrogen or argon. In addition, the heat treatment in an inert atmosphere is to use the tetrahedral structure of titanium used as an additive.

Next, the step of forming a target for sputtering by molding and sintering the powder into a desired shape is performed (S22). In this step, the molding can be molded by a general molding method such as press molding, and a molded body formed primarily by a press molding method is produced as a target sintered body for sputtering through a sintering process. Here, sintering is performed under atmospheric pressure, and sintering at 900 to 1400 ° C. under atmospheric pressure is preferable. After sintering, it can be cut to suit the sputtering target.

Subsequently, the cut sputtering target can be subjected to surface polishing in order to improve its surface state, and general polishing methods such as chemical polishing and mechanical polishing are used for polishing.

The sputtering target obtained through the above process can produce a transparent conductive film comprising a mixture of indium oxide and tin oxide mixed with titanium, wherein the ratio of the metal component in the target is indium 85 to 90 at%, titanium 1 to 1 It is preferably 5 at% and the remaining tin, and the target may further include +4 valent titanium oxide. In addition, it is preferable that the bulk resistance value of the said target is 1.50 * 10 <^-3> ohm * cm-1.35 * 10 <^-4> ohm * cm.

Subsequently, a step (S23) of depositing a transparent conductive film using the sputtering apparatus equipped with the sputtering target is performed. Here, the deposition is performed at room temperature by adjusting the initial vacuum degree in the chamber of the sputtering apparatus to 1 × 10 ⁻⁶ , and then adjusting the gas concentration and the deposition pressure to produce a transparent conductive film.

Subsequently, the prepared transparent conductive film is subjected to heat treatment at a temperature of 300 ° C. or less under oxygen, nitrogen, vacuum, or air atmosphere (S13). Preferably, the heat treatment is performed for 1 to 5 hours at a temperature of 50 to 250 ℃.

Since the transparent conductive film manufactured as described above has thermal stability, the transparent conductive film may be used in transparent electronic devices, and may also be used in flat panel displays such as LCDs, PDPs, OLEDs, or surface light source lighting devices.

Hereinafter, the present invention will be described in more detail with specific examples, but the present invention is not limited by the following examples.

Example

An alkali free glass substrate of 100 × 100 mm 2 was sequentially ultrasonically cleaned with acetone, isopropyl alcohol and deionized water. Subsequently, the dried indium oxide powder, tin oxide powder and titanium oxide powder having an average diameter of 0.5 to 1.0 µm were heat treated at 650 ° C. for 6 hours under a nitrogen atmosphere. Subsequently, the heat-treated powder was filled into a press molding machine and then press molded. Subsequently, the molded article obtained by press molding was sintered at atmospheric temperature for 6 hours at a temperature of 1200 ° C., and then cut and worked to produce a target for sputtering. In this case, the target for sputtering was 89 at%, titanium at 1 at%, and tin at 10 at%. Subsequently, the prepared sputtering target was mounted on an RF magnetron sputter, and the initial vacuum degree in the chamber was adjusted to 1 × 10 ⁻⁶ or less, and then In-Sn-Ti-O on the glass substrate at a thickness of 100 nm at ambient temperature. The thin film was deposited. Subsequently, the In—Sn—Ti—O-based thin film was heat treated at 250 ° C. for 2 hours in an air atmosphere.

Comparative example

An In—Sn—O based thin film was obtained in the same manner as in the above example except that no titanium oxide powder was used.

Test Example

Evaluation of Electrical Properties of Thin Films

The In-Sn-Ti-O-based thin film of Example and the In-Sn-O-based thin film of Comparative Example were heat-treated at 150 ° C, 250 ° C, 350 ° C, and 450 ° C, respectively, and their sheet resistance values were measured, respectively. 2 is shown. As can be seen from Figure 2, compared with the In-Sn-O-based thin film it can be seen that the In-Sn-Ti-O-based thin film is less change in the sheet resistance with temperature.

Amorphous Evaluation of Thin Films

Before and after the heat treatment of the In-Sn-O-based thin film obtained in the comparative example was measured by XRD and SEM, and the results are shown in Figures 3 and 5, respectively, In-Sn-Ti-O-based thin film obtained in the Example Before and after the heat treatment of the XRD and SEM by analyzing the results are shown in Figures 4 and 6.

From the above results, in the case of general In-Sn-O type, it can be seen that the crystallinity is generated by heat treatment at 250 ° C., although it shows amorphous characteristics. However, in the case of the In—Sn—Ti—O-based thin film of the present invention, even when there is no heat treatment, the crystallization is more reliably formed by heat treatment at 250 ° C. In addition, in the SEM measurement result of FIG. 4, in the case of the In-Sn-Ti-O-based thin film, smaller crystals than the In-Sn-O-based thin film are produced at the same fabrication temperature. As can be seen from FIG. 2 due to the difference in the microcrystalline structure, the increase in sheet resistance is not relatively large compared to the In—Sn—O based thin film.

1A is a flowchart illustrating a manufacturing process of a transparent conductive film according to an embodiment of the present invention.

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

2 is a graph showing a result of measuring sheet resistance according to annealing temperature of an ITO: Ti thin film according to an exemplary embodiment of the present invention.

3 is XRD measurement results before and after heat treatment of an ITO thin film according to a comparative example of the present invention.

4 is an XRD measurement result before and after heat treatment of an ITO: Ti thin film according to an embodiment of the present invention.

5 is a SEM measurement result before and after the heat treatment of the ITO thin film according to the comparative example of the present invention. (a) before heat treatment, (b) after heat treatment

6 is a SEM measurement result before and after the heat treatment of the ITO: Ti thin film according to an embodiment of the present invention. (a) before heat treatment, (b) after heat treatment

Claims (13)

A transparent conductive film comprising a mixture of indium oxide and tin oxide mixed with titanium, wherein the proportion of the metal component in the transparent conductive film is 85 to 90 at%, 1 to 5 at% titanium, and the remaining tin. Transparent conductive film with excellent stability. The transparent conductive film having excellent thermal stability according to claim 1, wherein the titanium is in the form of titanium oxide or metal titanium. delete A transparent conductive film comprising a mixture of indium oxide and tin oxide mixed with titanium, wherein the transparent conductive film further comprises + tetravalent titanium oxide. A transparent conductive film comprising a mixture of indium oxide and tin oxide mixed with titanium, wherein the transparent conductive film has a transmittance of 80 to 90% and a sheet resistance of 20 to 30 Ω · cm 2. membrane. Preparing a raw material powder comprising an indium oxide powder or a rare metal indium powder, a tin oxide powder or a metal tin powder, and a titanium oxide powder or a metal titanium powder; Forming a transparent conductive film from the raw material powder using a sputtering device; And The formed transparent conductive film is a method of producing a transparent conductive film having excellent thermal stability comprising the step of heat treatment at a temperature of less than 300 ℃. The method for manufacturing a transparent conductive film according to claim 6, wherein the raw material powder has a specific surface area of 8 to 12 m 2 / g and an average diameter of 0.5 to 1 m. The method for manufacturing a transparent conductive film according to claim 6, wherein the raw material powder is wet pulverized and dried. The method of claim 6, wherein the forming of the transparent conductive film Heat-treating the raw material powder in an inert atmosphere; Forming and sintering the powder into a desired shape to produce a sputtering target; And And depositing a transparent conductive film by using a sputtering apparatus equipped with the sputtering target. The method of claim 9, wherein the sintering is performed at 900 to 1400 ° C. under atmospheric pressure. 10. The method of claim 9, wherein the target is polished to improve the surface state of the target. The method of claim 9, wherein the transparent conductive film is deposited at an initial vacuum of 1 × 10 ⁻⁶ or less by using a sputtering apparatus. The method of claim 6, wherein the transparent conductive film is heat-treated at a temperature of 50 to 250 ℃.

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