KR101155059B1 - Indium tin oxide sintered body and target - Google Patents

Abstract

The present invention consists of indium oxide, tin oxide, and calcium-containing compounds, wherein the mass ratio of the indium oxide and the tin oxide is 90:10 to 91: 9 and the ratio of calcium atoms to indium atoms is 0.001 to 10 at%. An indium tin oxide sintered compact is provided. The indium tin oxide sintered body of the present invention exhibits a relative density of 99% or more, and the indium tin oxide target of the present invention formed from the sintered body can be formed for a long time due to the reduction of nodule and arcing during DC sputtering.

Description

Indium tin oxide sintered body and target

The present invention relates to an indium tin oxide (ITO) sintered body and a target, and relates to an indium tin oxide sintered body and a target in which generation of nodules and arcing is reduced by containing calcium.

ITO films containing indium tin oxide are used as transparent thin film electrodes in display devices such as liquid crystal displays (LCDs), organic light emitting diodes (OLEDs), and plasma display (PDP) devices due to their excellent properties such as high conductivity and transmittance of visible light. It is used a lot. The ITO transparent thin film electrode may be formed by chemical vapor deposition (CVD), atomic layer chemical vapor deposition (ALD), sputtering, or the like, but the sputtering method may be used due to the ease of forming a thin film and the ease of application to a large area substrate. This is widely used.

The sputtering method uses a target having a desired film component, and when argon plasma is generated by introducing a gas such as argon in a vacuum state and generating a discharge therebetween by using a substrate as an anode and a target as a cathode, an argon cation is generated. While colliding with the target of the cathode, the target component particles are dropped and deposited on the substrate to grow a film.

The sputtering method is a method using a high frequency plasma and a direct current plasma according to the generation method of argon plasma. Among these, the direct current plasma is mainly used because of its high film forming speed and easy operation.

In the sputtering method using the DC plasma, arcing or nodule is generated on the target surface during film formation, causing foreign matter to be mixed in the thin film, and causing a problem in that the film formation speed is inhibited. In particular, the arcing and nodule increase in number as the deposition time elapses, making the target unusable for a long time.

An object of the present invention is to solve the above problems, high-density indium tin oxide sintered body and target that can be used for a long time by suppressing the arcing and nodules that may occur during the film formation of the transparent conductive thin film by the sputtering method To provide.

An indium tin oxide (ITO) sintered body according to one feature of the present invention is composed of an indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ) and a calcium-containing compound, the indium oxide and the tin oxide The mass ratio of is 90: 10 to 91: 9 and the ratio of the calcium atom to the indium atom is characterized in that 0.001 to 10 at%.

The calcium-containing compound is characterized in that at least one selected from the group consisting of calcium oxide, calcium carbonate or calcium oxide tin and calcium indium oxide.

The indium tin oxide sintered compact is characterized by having a relative density of 99% or more.

The indium tin oxide sintered body is made of a calcium-containing compound powder having an average particle diameter of 0.1 to 2 ㎛.

An indium oxide target according to one feature of the present invention is formed by processing an indium tin oxide sintered body according to the present invention and joining it to a cooling metal plate.

When DC sputtering is performed for 30 hours with the indium tin oxide target, the occurrence of arcing appears less than 50 times.

The indium tin oxide target was deposited by DC sputtering at a temperature of 200 ° C., and the resistivity of the thin film formed to a thickness of 200 nm or less was 1.4 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ Ω · cm, and average transmittance in the visible light region. This represents more than 80%.

The indium tin oxide sintered body and the target according to the present invention contain calcium-containing compounds, and thus, the formation of arcing and nodules is less than that of the conventional indium tin oxide sintered body and the target, and thus high-speed film formation is possible.

In addition, the target for indium tin oxide sputtering according to the present invention can be sputtered for a long time, thereby improving the efficiency of the manufacturing process.

Indium tin oxide (ITO) sintered body according to an embodiment of the present invention is made of indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ) and calcium-containing compounds, the indium oxide and the oxidation The mass ratio of tin is 90:10 to 91: 9, and the ratio of calcium atoms to indium atoms is 0.001 to 10 at%. The calcium-containing compound consists of calcium oxide, calcium carbonate or calcium oxide tin, indium calcium oxide, or a combination thereof. The indium tin oxide sintered compact has a relative density of 99% or more. The indium tin oxide sintered body is made of a calcium-containing compound powder having an average particle diameter of 0.1 to 2 m.

An indium oxide target according to an embodiment of the present invention is formed by processing the above indium tin oxide sintered body and joining to a cooling metal plate. Arcing occurs less than 50 times when the deposition time is 30 hours when DC sputtering with the indium tin oxide target. The indium tin oxide target was deposited by DC sputtering at a temperature of 200 ° C., and the resistivity of the thin film formed to a thickness of 200 nm or less was 1.4 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ Ω · cm, and average transmittance in the visible light region. This represents more than 80%.

Such a method of manufacturing the indium tin oxide sintered body of the present invention is a slurry preparation step of preparing a slurry by mixing indium oxide powder, tin oxide powder and calcium-containing compound powder, milling and drying the slurry to prepare a dry powder A powdering step, a molding step of molding the dry powder to produce a molded body, and a sintering step of sintering the molded body.

The calcium-containing compound may be at least one selected from the group consisting of calcium oxide, calcium carbonate or calcium oxide tin and calcium indium oxide. Each compound may be used alone or in combination of two or more.

The average particle diameter of the said calcium containing compound powder is 0.1-2 micrometers. In addition, the calcium-containing compound powder may be added so that the ratio of the calcium atoms to the indium atoms of the indium oxide powder is a ratio of 0.001 to 10 at%.

The average particle diameter of the indium oxide powder is 0.1 to 1 μm, and the average particle diameter of the tin oxide powder is 1 to 5 μm. The mass ratio of the indium oxide powder to the tin oxide powder is preferably 90:10 to 91: 9.

At least one compound selected from the group consisting of a binder, a dispersant, and an antifoaming agent may be added to the slurry in the slurry preparation step, and the sintering step is performed under an oxygen or air atmosphere at a temperature of 1400 to 1600 ° C.

The indium tin oxide sintered body and target in the present invention are prepared by the above method, contain 0.001 to 10 at% of calcium relative to the indium atom, and exhibit a relative density of 99% or more.

Hereinafter, a method of manufacturing the indium tin oxide sintered body according to an embodiment of the present invention will be described in detail.

The method for producing an indium tin oxide sintered compact according to the present invention includes a slurry preparation step, a powdering step, a molding step, and a sintering step.

In the slurry preparation step, an appropriate amount of water is added to a container, and indium oxide (In ₂ O ₃ ) powder, tin oxide (SnO ₂ ) powder, and calcium oxide tin powder (CaSnO ₃ ) are added to the container, and then Mix the powder to prepare the slurry.

In the present embodiment, calcium tin oxide was used in the slurry preparation step. Alternatively, calcium indium oxide (CaIn ₂ O ₄ ), calcium carbonate, or calcium oxide may be used, and in some cases, two or more compounds may be used at a constant ratio. It can also be mixed and used.

When preparing the slurry as described above, the use of the calcium tin oxide or the calcium indium oxide, compared to using other types of Ca-containing oxides such as CaO or CaCO ₃ , to the production of CO and CO ₂ gas in the subsequent sintering process It is possible to prevent the sintered density from deteriorating and to improve the dispersibility of Ca.

The indium oxide powder, the tin oxide powder and the calcium oxide powder may be in a state in which the particle size is pulverized to several micrometers or less before mixing.

The average particle diameter of the indium oxide powder is 0.1 to 1 m, and the average particle diameter of the tin oxide powder is 1 to 5 m.

When the powder is mixed as described above, the indium oxide powder and the tin oxide powder are mixed so that the atomic number ratio of Sn / In is 20at%.

The mass ratio of the indium oxide powder and the tin oxide powder is 90:10 to 91: 9, and preferably 90:10 to 90.2: 9.8.

The average particle diameter of the said calcium oxide tin powder is 0.1-2 micrometers, Preferably it is 0.1-1 micrometer. In this case, when the particle size of the calcium tin oxide powder is small, since the solid solubility with indium oxide and tin oxide is increased, the particle size is preferably adjusted to 1 µm or less.

The addition amount of the calcium oxide tin powder is 0.001 to 10 at%, preferably 0.001 to 0.3 at%, of the ratio of calcium atoms to indium atoms of the indium oxide powder. In this case, when the calcium content is less than 0.001 at%, the effect of reducing arcing and nodule decreases, whereas when the calcium content exceeds 10 at%, the resistance of the thin film formed through sputtering becomes high. It is not suitable to be used as a transparent conductive film such as LCD.

When the powder is mixed as described above, an additive may be added to the slurry as necessary. The additive according to an embodiment of the present invention is at least one compound selected from the group consisting of a binder, a dispersant and an antifoaming agent.

The dispersant is added in order to satisfy the purpose for the finely ground particles to be pulverized while at the same time maintaining the dispersed dispersion of the raw material particles evenly stable in the solution for a long time. As the dispersant, an organic acid series having a carboxyl group such as citric acid (CA), polyacrylic acid (PAA) or a salt thereof, or a copolymer thereof may be used. The dispersants may be used alone or in combination of two or more. The amount of the dispersant added is preferably 0.5 to 3% by weight relative to the powder in the slurry.

The binder is added to maintain the molding strength of the molded body in the process of drying the slurry to powder and may be a polymer such as polyvinyl alcohol (PVA), polyethylene glycol (PEG), etc. . The polymers may be used alone or in combination of two or more. The amount of the binder added may be 0.01 to 5% by weight, preferably 0.5 to 3% by weight relative to the powder in the slurry.

The antifoaming agent is for removing bubbles in the slurry, and typically, silicone oil, octyl alcohol, boric acid, and the like may be used, but the present invention is not limited thereto. The amount of the antifoaming agent is preferably 0.001 to 0.01% by weight relative to the powder in the slurry.

The organic solvents such as the dispersant, the binder, the antifoaming agent, and the like, when used in excess, may lower the density of the sintered body to be produced later.

Next, the powdering step and the molding step will be described.

In the slurry preparation step, the slurry prepared by mixing indium oxide powder, tin oxide powder, calcium oxide powder, water and additives is milled and dried to prepare a dry powder. In the milling, a ball mill, a bead mill, and the like may be used, but a wet milling method is generally used, but the present invention is not limited thereto. It is preferable that the viscosity of the slurry obtained through milling is 100 cps or less. When the said viscosity is higher than 100 cps, the particle size in a slurry is large and dispersibility falls and it becomes a cause of the density fall of a sintered compact after sintering.

After milling as above, the slurry is spray dried using a spray dryer or the like to obtain a dry powder.

Next, the dried powder is subjected to a molding step of producing a molded body in a constant shape. In manufacturing the molded body, it is preferable to use a cold isostatic press (CIP) in consideration of process convenience and the like.

After the molding step, the indium tin oxide sintered body is manufactured through the sintering step. The sintering step may be performed under an oxygen atmosphere, an air and oxygen mixed atmosphere, or an air atmosphere. The sintering step is carried out at a temperature of 1400 to 1600 ℃, preferably sintered under oxygen atmosphere at a temperature of 1500 to 1600 ℃. The temperature range of the sintering step is related to the density of the sintered compact, and when sintered at a temperature of 1500 to 1600 ° C, the indium tin oxide sintered compact has a relative density of 99% or more relative to the theoretical density (7.152 g / cm ³ ). You can get it.

The sintered body is processed into a constant size and shape and pasted onto a cooling metal plate or a backing plate to be used as a sputtering target. In this case, an indium tin oxide transparent electrode can be manufactured by supplying argon gas containing 0.1% oxygen gas at a rate of 80 sccm in a vacuum chamber to form a film.

Hereinafter, the indium tin oxide sintered body and the method of manufacturing the target according to the present invention will be described in more detail with reference to the following examples, but the following examples are illustrative for explaining the indium tin oxide sintered body and the target according to the present invention in more detail. However, the content of the present invention is not limited to the following examples.

Example 1

1800 g of indium oxide powder having a purity of 99.99% and an average particle diameter of 1 μm or less, 200 g of tin oxide powder having a purity of 99.9% and an average particle diameter of 3 μm, and 2 g of calcium oxide tin powder having a purity of 99% and an average particle diameter of 1 μm are mixed with 1 L of water. To prepare a slurry. 200 g of 10 wt% dilute polyvinyl alcohol (PVA), 30 g of a dispersant, and 0.1 g of an antifoam were added to the slurry to obtain a mixed slurry.

The slurry was mixed and pulverized using a bead mill for 20 minutes, and then spray dried using a spray dryer to obtain a dry powder. The dry powder was manufactured into a molded body through a CIP process after uniaxial pressure molding at a pressure of 18 ton / cm ² to have a diameter of 3 inches and a thickness of 1 cm.

The molded body was sintered at 1550 ° C. for 6 hours in an oxygen atmosphere to obtain an indium tin oxide sintered body. The relative density with respect to the theoretical density (7.152g / cm <^3> ) of the said sintered compact is shown in Table 1.

The sintered body was processed to a diameter of 3 inches and a thickness of 7 mm to melt an indium metal in a copper backing plate and to prepare a indium tin oxide target.

The indium tin oxide target was mounted on a DC magnetron sputtering apparatus, and high vacuum was maintained to supply argon gas containing 0.1% of oxygen gas at a rate of 80 sccm. While the film was formed for 30 hours at an input power of 100 W, the number of generated arcs was measured every hour using an arc counter, and the generated number of arcs was shown as a cumulative arc in FIG. In addition, the photograph of the target surface after 30 hours is shown in FIG.

Comparative Example 1

Calcium carbonate powder was added instead of the calcium oxide tin powder in preparing the slurry, and the indium tin oxide target was prepared in the same manner as in Example 1.

In addition, the relative density with respect to the theoretical density (7.152g / cm ³ ) of the sintered body produced by the above manufacturing process is shown in Table 1.

Thereafter, the number of arcs generated per hour through DC magnetron sputtering was measured under the same conditions as in Example 1, and the cumulative arcs are shown in FIG. 1, and a photograph of the target surface after 30 hours is shown in FIG. 3.

Comparative Example 2

In preparing a slurry, an indium tin oxide target was prepared in the same manner as in Example 1 without adding a calcium additive such as calcium tin oxide powder or calcium carbonate powder.

In addition, the relative density with respect to the theoretical density (7.152g / cm ³ ) of the sintered body produced by the above manufacturing process is shown in Table 1.

Thereafter, the number of occurrences of arcs per hour was measured by DC magnetron sputtering under the same conditions as in Example 1, and the cumulative arcs are shown in FIG. 1, and a photograph of the target surface after 30 hours is shown in FIG. 4.

Example 1 Comparative Example 1 Comparative Example 2 Relative Density (%) 99.9 99.55 99.66

First, referring to Table 1, in the case of Example 1 to which calcium oxide tin was added, the prepared sintered body showed a higher relative density than Comparative Example 1 to which calcium carbonate was added or Comparative Example 2 to which nothing was added. This is the result shown that to obtain a high density sintered body than in comparison to suppress CO _X gas is generated by the addition of the tin, calcium oxide, Examples 1 and 2.

Referring to FIG. 1, when calcium tin oxide is added, only 46 accumulated arcs are generated after 30 hours, whereas when calcium carbonate is added and there is no Ca additive, the accumulated arcs are 210 and 3641, respectively. appear.

Referring to FIG. 2, when calcium tin oxide was added, the generation of nodules was the least. Referring to FIG. 3, the addition of calcium carbonate was more likely to produce nodules compared to the case where calcium oxide was added. Referring to FIG. 4, it could be seen that in the absence of a calcium additive, considerably more nodules were generated than when the calcium oxide was added or when the calcium carbonate was added.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a graph showing the cumulative arc with respect to time according to Example 1, Comparative Example 1 and Comparative Example 2.

FIG. 2 is a photograph of the surface of the target taken after depositing an indium tin oxide target prepared in Example 1 for 30 hours. FIG.

FIG. 3 is a surface photograph of a target taken after forming an indium tin oxide target prepared in Comparative Example 1 for 30 hours. FIG.

FIG. 4 is a surface photograph of a target taken after forming an indium tin oxide target prepared in Comparative Example 2 for 30 hours. FIG.

Claims (7)

Consisting of indium oxide, tin oxide, and calcium containing compounds, A mass ratio of the indium oxide and the tin oxide is 90:10 to 91: 9 and the ratio of calcium atoms to indium atoms is 0.001 to 10 at%. The method of claim 1, The calcium-containing compound is indium tin oxide sintered body characterized in that at least one selected from the group consisting of calcium oxide, calcium carbonate or calcium oxide tin and calcium indium oxide. The method of claim 1, The indium tin oxide sintered body has a relative density of 99% or more. The method of claim 1, The indium tin oxide sintered body is an indium tin oxide sintered body, which is made of a calcium-containing compound powder having an average particle diameter of 0.1 to 2 ㎛. An indium tin oxide target, wherein the sintered compact according to any one of claims 1 to 4 is processed and joined to a cooling metal plate. The method of claim 5, Indium tin oxide target, characterized in that the occurrence of arcing less than 50 times when the film formation time is 30 hours during DC sputtering with the indium tin oxide target. The method of claim 5, The indium tin oxide target was deposited by DC sputtering at a temperature of 200 ° C., and the resistivity of the thin film formed to a thickness of 200 nm or less was 1.4 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ Ω · cm, and average transmittance in the visible light region. 80% or more of the indium tin oxide target.

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