KR102272222B1 - Manufacturing method of high purity ITO target - Google Patents

Abstract

The high-purity ITO target manufacturing method of this embodiment comprises the steps of mixing indium metal so that the tin content is 10 wt% or less, and then proceeding with an oxidation process to prepare an alloying powder, and applying the powder to a mold made of stainless steel. After inserting, uniaxial molding at a preset pressure, hydrostatic pressure molding using water to form a powder compact, and putting the powder compact into a mold made of SiC, as a primary sintering process, pressurized preliminary heat treatment Including; performing a second sintering process on the sintered body formed by performing the first sintering process, wherein the primary sintering process is a heat treatment at 1,000 to 1,100° C. at a preset pressure A first heat treatment process to be performed, and a second heat treatment process for performing heat treatment at 1,500 to 1,550 ° C. without external pressure, wherein the first sintering process is performed by putting the powder compact into a mold made of a silicon carbide material and performing heat treatment, , The mold is characterized in that it consists of two punches arranged vertically.

Description

Manufacturing method of high purity ITO target

The present invention relates to a method capable of manufacturing a high-purity ITO target powder through vapor phase synthesis and a two-step sintering process, and while simplifying the manufacturing process, the alloy powder has excellent properties such as cohesiveness, particle size and distribution it's about how to be

ITO (composite oxide of indium-tin) film is widely used as a transparent conductive film of display devices centering on liquid crystal displays. As a method of forming the ITO film, a magnetron sputtering method having excellent operability or film stability is mainly used.

The ITO sputtering target is manufactured using a general ceramics process. At this time, the raw material uses nano-grade ceramic powder and is manufactured using the ceramics process in the order of mixing, molding, sintering, processing, and bonding.

In the conventional ITO target, indium oxide powder and tin oxide powder are physically mixed and used. The sputtering target must have a high sintering density, and it is very important to ensure the homogeneity of the components. Since each characteristic is often influenced by the characteristics of ceramic fine powder used as a raw material, the development of raw materials is classified as an important technical matter along with sintering technology.

When a device is manufactured using sputtering, nodules and particles are often generated, which reduces the yield of the display and causes various productivity problems such as defective pixels. Therefore, most target manufacturers who manufacture sputtering targets are making efforts to improve the high density, the homogeneity of the composition, and the cleanliness of the surface in order to overcome this, and the importance of the homogeneity of the composition is increasing in recent years.

If indium and tin are not uniform, it induces non-uniformity of electrical conductivity, and thus the etching of the target is also non-uniform.

The present invention aims to make it possible to manufacture indium and tin, which are raw material powders of a target for a transparent conductor, in an alloyed state in the powder particles. We would like to propose a method for manufacturing a high-purity IOT target that can secure

The high-purity ITO target manufacturing method of this embodiment comprises the steps of mixing indium metal so that the tin content is 10 wt% or less, and then proceeding with an oxidation process to prepare an alloying powder, and applying the powder to a mold made of stainless steel. After inserting, uniaxial molding at a preset pressure, hydrostatic pressure molding using water to form a powder compact, and putting the powder compact into a mold made of SiC, as a primary sintering process, pressurized preliminary heat treatment Including; performing a second sintering process on the sintered body formed by performing the first sintering process, wherein the primary sintering process is a heat treatment at 1,000 to 1,100° C. at a preset pressure A first heat treatment process to be performed and a second heat treatment process for performing heat treatment at 1,500 to 1,550 ° C. without external pressure, wherein the first sintering process is performed by putting the powder compact into a mold made of a silicon carbide material and performing heat treatment , The mold is characterized in that it consists of two punches arranged vertically.

By the manufacturing method as proposed, the production of high-purity ITO target powder is made possible through a simple process, and in particular, high yield and oxidation at atmospheric pressure are possible, thereby reducing installation cost and securing stability.

1 is a flowchart illustrating a method of manufacturing a high-purity IOT target according to an embodiment of the present invention.
2 is a graph showing the relative density of the prepared molded article specimen.
3 is a view showing a mold for pressing the sintered body according to the present embodiment.
4 is a photograph showing the pore size when the heat treatment process is performed according to the present embodiment and when the heat treatment process is not performed.
5 is a graph showing the specific surface area and production yield according to the ratio of indium and tin.
6 is a graph showing the X-ray diffraction characteristic test results according to the mixing ratio of indium and tin.

Hereinafter, the technical features of the present invention will be described in detail with accompanying drawings.

Conventional ITO target manufacturing included powder mixing, drying, calcining and pulverizing processes, but in the present invention, these existing processes can be shortened to consist of mixing and oxidation processes, and despite the shortening of the process, the particle size It is possible to manufacture a fine powder with little cohesiveness, so it is possible to manufacture a high-quality ITO target.

In the present invention, the indium tin oxide powder produced through the mixing of indium and tin and the oxidation process of these mixtures is molded into a desired shape, and then the primary sintering process and the secondary sintering process are performed, Through this process, the manufacturing process is simplified, the yield is excellent, and since the material itself is high vapor pressure, oxidation is possible at normal pressure.

And, since it is not necessary to use a reactor that has to withstand high pressure, it is possible to reduce the equipment cost and increase the stability for the production of the oxide powder.

In particular, there is an advantage of being environmentally friendly because no acid or basic harmful substances are formed during the production of the ITO alloy powder, and the waste raw material can be recycled in the manufacturing process of this embodiment after the powder is manufactured.

1 is a flowchart illustrating a method of manufacturing a high-purity IOT target according to an embodiment of the present invention.

The manufacturing method of the embodiment includes a powder manufacturing process (S10) of mixing tin metal and indium metal, a molding process (S20) of forming the powder into a compact, and a sintering process (S30) of oxidizing/sintering the compact.

1. Powder manufacturing

In this embodiment, a high-purity ITO target powder is manufactured, and in the following examples, the mixing ratio (weight ratio) of indium and tin is 9:1. However, it goes without saying that the mixing ratio of indium and tin may be variously changed according to the request of the customer.

2. Mold molding

Molding of the molded body is not particularly limited, and may be variously molded, such as round, rectangular, etc. according to the request of the customer or the selection of the manufacturer.

For example, in this example, 1 g of powder is weighed for the specimen, put into a mold with a diameter of 12.7 mm made of stainless steel, and then uniaxially molded at 1 MPa, and then the disk-shaped specimen is placed in a rubber bag and water is is hydrostatically pressed at 100 MPa.

2 is a graph showing the relative density of the produced specimen of the molded body, and as shown, the relative density of the specimen prepared according to this embodiment is in the range of 60.13 to 67.37%.

3. Sintering process

In the present embodiment, the sintering process ( S30 ) is a preliminary sintering process corresponding to the primary sintering process, and the main sintering corresponding to the secondary sintering process is sequentially performed.

First, a pressure preliminary heat treatment is performed on the powder compact as a primary sintering process. In the primary sintering process, the sintered body is pressed by using a mold as shown in FIG. 3 , and the illustrated mold is made of a silicon carbide (SiC) material, and the mold can withstand a temperature of 1,000 to 1,100 ° C. and has an inner diameter of 1.5 cm.

Two upper and lower punches are configured in the mold, and are configured to transmit the pressure transmitted from the compressor, and the alumina powder is disposed between the mold punch and the specimen (formed product before sintering).

Here, the alumina powder serves to facilitate separation of the specimen after bonding to the mold punch when the mold punch is pressed at 1,000 to 1,100°C.

The results of the analysis of the densification behavior according to the ratio of indium and tin are used. In order to use them as a target, it is essential to remove electrically heterogeneous elements such as pores and secondary phases. For this purpose, it is necessary to manufacture a more dense target, and it is necessary to make it composed of particularly fine particles. This is because nodules may grow due to non-uniform etching while using the target, which may cause particle formation and cause product defects. In the present invention, by performing the above secondary sintering process, densification and grain growth suppression were achieved.

When performing the pressure preliminary heat treatment process using the mold, the heat treatment schedule is as follows.

Under the condition of applying a pressure of 1 MPa, heat treatment was performed at 1,000 to 1,100 °C for 10 minutes, and main sintering was carried out at 1,500 to 1,550 °C for 2 hours without external pressure. At this time, the temperature increase rate was all maintained at 5 °C / min.

In particular, according to this embodiment, the heat treatment process in the first sintering process is performed with a first heat treatment and a second heat treatment at different temperature conditions and time, which is to manufacture a specimen with high relative density in order to manufacture a high-quality ITO target to do

This is because pores are formed in the sintered specimen, and even with the same volume of pores (porosity), the greater the number of small pores than large pores, the more advantageous for densification. In addition, when the size of the pores is reduced through this heat treatment in the primary sintering process, the relative density is greatly affected even in the main sintering process, which is the secondary sintering process.

4 is a photograph showing the pore size when the heat treatment process is performed according to the present embodiment and when the heat treatment process is not performed.

In Figure 4, when the general sintering process is performed at 1,500 ° C. (A), when the primary heat treatment and the secondary heat treatment as described above are performed at 1,000 to 1,500 ° C (B), and the primary heat treatment at 1,100 to 1,500 ° C. and (C) are shown when the secondary heat treatment is performed.

In the case of B and C, there is no significant difference, but as the primary heat treatment is performed at 1,000 to 1,100°C and the secondary heat treatment is performed at 1,500 to 1,550°C without external pressure, the relative density of the target is the same as the experimental results in Table 1. It can be seen that there is a significant decrease.

After performing the primary sintering process (pre-sintering) as described above, a secondary sintering process (main sintering) is performed, and the secondary sintering process is performed as follows.

Table 2 above is an experimental result confirming the particle size of the high-purity ITO powder prepared according to this Example, and shows the result of the experiment at 1,450° C. in an In:Sn ratio.

As shown in Table 2 above, _{it was confirmed to have a particle size of D 10} 0.1㎛, D ₅₀ 0.7㎛, D ₉₀ 1.5㎛ or less, and has a specific surface area of 9.7 ~ 10.7 m ² /g range. The powder having such a particle size and specific surface area is very dense, and has excellent performance as a powder for manufacturing a high-purity ITO target.

5 is a graph showing the specific surface area and production yield according to the ratio of indium and tin. As shown in FIG. 5 , as the content of indium increased, the production yield tended to decrease, and on the contrary, it was confirmed that the specific surface area increased.

6 is a graph showing the X-ray diffraction characteristic test results according to the mixing ratio of indium and tin.

As shown in Figure 6, when the tin (Sn) content was added 50 ~ 15wt% SnO ₂ Peak was observed as a secondary phase (second phase), only the pure ITO peak was observed from the tin content 10wt% or less. From these experimental data, it is possible to know the limit of the Sn content for ITO synthesis.

Therefore, the solid solution limit of Sn is preferably 10wt%, and when the content of Sn is added to 10wt% or less, a high-purity ITO target can be manufactured.

Claims (4)

Preparing an alloying powder by mixing an indium metal while the content of tin is 10 wt% or less, and then performing an oxidation process;
Putting the powder into a mold made of stainless steel, uniaxially molding with a predetermined pressure, and hydrostatically molding with water to form a powder compact;
After putting the powder compact into a mold made of SiC, performing a pressure preliminary heat treatment as a primary sintering process;
and performing a secondary sintering process on the sintered body formed by performing the primary sintering process.
The primary sintering process includes a primary heat treatment process in which heat treatment is performed at 1,000 to 1,100° C. with a preset pressure, and a secondary heat treatment process in which heat treatment is performed without external pressure at 1,500 to 1,550° C.,
In the primary sintering process, heat treatment is performed by putting the powder compact into a mold made of silicon carbide,
The mold is a high-purity IOT target manufacturing method, characterized in that consisting of two punches arranged vertically. The method of claim 1,
Alumina powder for facilitating separation after bonding between the powder compact and the punch is disposed between the two punches,
The punch is a high-purity IOT target manufacturing method, characterized in that the process is performed to press the powder compact at a temperature in the range of 1,000 ~ 1,100 ℃.
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