KR20090113573A - Indium tin oxide target and manufacturing method of the same - Google Patents

Abstract

PURPOSE: An indium tin oxide target and a manufacturing method thereof are provided to improve efficiency of a manufacturing process with long-termed sputtering. CONSTITUTION: A manufacturing method of an indium tin oxide target includes the following steps of: preparing slurry by mixing indium oxide powder, tin oxide powder and cerium containing compound powder; preparing drying powder after milling the slurry; manufacturing a molding body by molding the drying powder; and sintering the molded body. The cerium containing compound is selected from a group consisting of ceria or ceria tin, and ceria indium. The indium tin oxide target has the relative density of 99% or greater.

Description

Indium tin oxide target and manufacturing method of the same

The present invention relates to an indium tin oxide target, and more particularly, DC sputtering and high density indium tin oxide capable of high-speed film formation and long-term use by suppressing occurrence of arcing and nodules that may occur during film formation of a transparent conductive thin film. It is about a target.

Indium tin oxide (ITO) films containing indium tin oxide 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 widely used as a transparent thin film electrode in. 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. In addition, when calcium carbonate is added as a calcium-containing compound in the target for the purpose of preventing nodules or arcing, a problem of lowering the sintered density due to carbon dioxide generation may occur in the process. Therefore, there is a demand for the development of a new target to reduce the occurrence of nodules and arcing and at the same time reduce the failure rate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-density indium tin oxide target capable of high-speed film formation and long-term use by suppressing arcing and nodules that may occur during film formation of a transparent conductive thin film by sputtering. .

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

An indium tin oxide (ITO) target according to an aspect of the present invention includes an indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), and a cerium-containing compound, wherein the indium oxide and the tin oxide are The mass ratio of is 90: 10 to 91: 9 and the ratio of cerium atoms to indium atoms is characterized in that 0.175 at% or less.

The cerium-containing compound is at least one selected from the group consisting of cerium oxide or cerium oxide tin and cerium indium oxide.

In addition, the indium tin oxide target is characterized in that the relative density is 99% or more.

The indium tin oxide target is characterized in that the cerium 유 containing compound powder having an average particle diameter of 0.1 to 5 ㎛.

When DC sputtering is performed for 48 hours with the indium tin oxide target, arcing occurs less than 1000 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%.

In the method for producing an indium tin oxide target according to an aspect of the present invention, a slurry preparation step of preparing a slurry by mixing indium oxide powder, tin oxide powder and cerium-containing compound powder, milling and drying the slurry to prepare a dry powder And a sintering step for sintering the molded body, and a molding step for forming a molded body by molding the dry powder.

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

The average particle diameter of the cerium-containing compound powder is 0.1 to 5 탆. In addition, the cerium-containing compound powder is added so that the ratio of cerium atoms to indium atoms of the indium oxide powder is 0.175 at% or less.

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

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

The indium tin oxide target in the present invention is prepared by the above method, contains less than 0.175 at% of cerium relative to the indium atom, and exhibits a relative density of 99% or more.

As described above, the indium tin oxide target according to the present invention includes a cerium-containing compound, and thus, the formation of arcing and nodule is less than that of the conventional indium tin oxide target, thereby enabling high-speed film formation.

In addition, the indium tin oxide target can be sputtered for a long time to increase the efficiency of the manufacturing process and lower the defective rate.

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

The method for producing an indium tin oxide target 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 cerium oxide powder (CeO ₂ ) are added to the container, and then the powder To prepare a slurry by mixing.

In the present embodiment, cerium oxide is used in the slurry preparation step. Alternatively, cerium oxide, cerium oxide, or the like may be used. Alternatively, two or more compounds may be mixed and used at a predetermined ratio.

The indium oxide powder, the tin oxide powder, and the cerium oxide powder may be in a state in which the particle size is pulverized to several μm 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 cerium oxide powder is 0.1 to 5 mu m, preferably 0.1 to 1 mu m. In this case, when the particle size of the cerium oxide powder is small, the dispersibility with indium oxide and tin oxide is increased, so that the particle size is preferably adjusted to 1 µm or less.

The amount of the cerium oxide powder added is 0.175 at% or less, preferably 0.001 to 0.175 at%, more preferably 0.001 to 0.1 at%. at% represents the percentage of the number of atoms. When the content of cerium is less than 0.001 at%, the effect of reducing arcing and nodule decreases. On the other hand, when the content of cerium exceeds 0.175 at%, the resistance of the thin film formed through sputtering is increased, such as LCD. It is not suitable for use as a transparent conductive film.

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, a copolymer, or the like is 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, a slurry prepared by mixing indium oxide powder, tin oxide powder, cerium oxide tin powder, water, and an additive 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, an indium tin oxide target and a method of manufacturing the same according to the present invention will be described in more detail with reference to the following examples. As the content of the present invention is not limited to the following examples.

EXAMPLE

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 1 g of cerium oxide powder having a purity of 99.9% and an average particle diameter of 2 μm are mixed with 1 L of water. The slurry was prepared. 200 g of 10 wt% dilute polyvinyl alcohol (PVA), 30 g of a dispersant, and 0.1 g of an antifoaming agent 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 dried powder was manufactured into a molded body through a CIP process after uniaxial pressure molding at a pressure of 300 ton to have a width of 40 cm, a length of 12 cm, and a thickness of 1 cm.

The molded body was taken to indium tin oxide sintered body sintered at 1550 ℃ for 6 hours under an oxygen atmosphere, the density is even in the Ce added as a relative density of 99.80% (theoretical density = 7.152g / cm ^3), and obtain a high density sintered body Could.

After processing the sintered body 26cm long, 9cm long, 5mm thick and then melted and bonded 3 pieces of indium metal to a copper backing plate was prepared as an indium tin oxide of 80cm wide, 10cm long.

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 48 hours of film formation was performed at an input power of 1.5 kW, 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 48 hours is shown in FIG.

As a result, after 48 hours, arc generation was only 798, and as shown in FIG. 2, the occurrence frequency of the module was also reduced.

[Comparative Example]

An indium tin oxide target was prepared in the same manner as in Example, without adding a cerium-containing compound such as cerium oxide powder in preparing the slurry.

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 was shown as 99.82%.

Thereafter, the number of occurrences of arcs per hour was measured by DC magnetron sputtering under the same conditions as in the above example, and is represented as a cumulative arc in FIG. 1B, and a photograph of the target surface after 48 hours is shown in FIG. 3.

As a result, after 48 hours, the arc generation was 1428 more than twice as much as the target added CeO ₂ , and as shown in FIG.

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 number of cumulative arc generations with respect to time according to Example (A) and Comparative Example (B).

FIG. 2 is a photograph of the surface of a target obtained after forming an indium tin oxide target prepared according to an embodiment of the present invention for 48 hours under 1.5KW condition (power density 2.18W / cm ² ).

FIG. 3 is a surface photograph of a target taken after forming an indium tin oxide target prepared according to a comparative example for 48 hours under 1.5KW conditions (power density 2.18W / cm ² ).

Claims (8)

Consisting of indium oxide, tin oxide, and cerium containing compounds, The mass ratio of the indium oxide and the tin oxide is 90:10 to 91: 9 and the indium tin oxide target is characterized in that the ratio of cerium atoms to indium atoms is 0.175 at% or less. The method of claim 1, The cerium-containing compound is at least one selected from the group consisting of cerium oxide or cerium oxide and cerium indium oxide. The method of claim 1, The indium tin oxide target is an indium tin oxide target, characterized in that the relative density is 99% or more. The method of claim 1, The indium tin oxide target is an indium tin oxide target, characterized in that made of cerium-containing compound powder having an average particle diameter of 0.1 to 5 ㎛. The method of claim 1, Indium tin oxide target, characterized in that the occurrence of arcing less than 1000 times when the film formation time is 48 hours when DC sputtering with the indium tin oxide target. The method of claim 1, The indium tin oxide target was deposited by DC sputtering at a temperature of 200 ° C., and the specific resistance of the thin film formed to a thickness of 200 nm or less was 1.4 × 10 ⁻⁴ to 2.5 × 10 ⁻⁴ Ω · cm, and average transmittance in the visible light region. 80% or more of the indium tin oxide target. A slurry preparation step of preparing a slurry by mixing indium oxide powder, tin oxide powder, and cerium-containing compound powder; A powdering step of preparing a dry powder by milling and drying the slurry; A molding step of forming a molded body by molding the dry powder; And A sintering step of sintering the molded body; Method for producing an indium tin oxide target comprising a. The method of claim 7, wherein the slurry preparation step, A method for producing an indium tin oxide target, characterized in that the cerium-containing compound powder is added so that the ratio of cerium atoms to the indium atoms of the indium oxide powder is 0.175 at% or less.

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