KR100814320B1 - Method for producing sputtering target - Google Patents

Abstract

Provided is a method for producing a sputtering target, which can extend the life of the target and obtain a high-density sputtering target.

When firing a raw powder comprising a mixed powder comprising indium oxide powder and tin oxide powder to produce a sputtering target, at least indium oxide is calcined at 1100 ° C. to 1300 ° C. to obtain a mixed powder of the raw material, and the mixed powder is It bakes at temperature higher than 150 degreeC from the calcined temperature.

Target, Life, Sputtering Target, Indium Oxide Powder, Tin Oxide Powder, Calcined.

Description

Manufacturing method of sputtering target {METHOD FOR PRODUCING SPUTTERING TARGET}

The present invention relates to a method for producing a sputtering target.

Generally, sputtering is known as one of methods for forming a thin film. The sputtering method is a method of obtaining a thin film by sputtering a sputtering target. Since the large area is easy and a high performance film can be formed efficiently, it is industrially used. Recently, as a sputtering method, a reactive sputtering method for sputtering in a reactive gas, a magnetron sputtering method for accelerating thin film formation by providing a magnet on the back surface of a target and the like are also known.

Among the thin films used in such a sputtering method, an indium tin oxide (composite oxide of In ₂ O ₃ -SnO ₂ , hereinafter referred to as "ITO") film is particularly transparent because of its high visible light transmittance and high conductivity. As a film, it is widely used for a liquid crystal display device, a heat generating film for preventing condensation of glass, an infrared reflecting film, and the like.

For this reason, in order to form a film with low cost more efficiently, improvement of sputter | spatter conditions, a sputter apparatus, etc. is performed day by day, and it becomes important how to operate an apparatus efficiently. In addition, in such an ITO sputtering, the short time between setting the new sputtering target and the initial arc (abnormal discharge) disappears and the product can be manufactured, and how long it can be used after setting it (accumulation) Sputtering time: target life) is a problem.

Such an ITO sputtering target is formed by mixing indium oxide powder and tin oxide powder in a predetermined ratio, dry or wet molding, and sintering (Patent Document 1). A highly dispersible indium oxide powder for obtaining a high density ITO sintered body is proposed. (Refer patent document 2, 3, 4, etc.).

On the other hand, it is also known to make ITO powder wet-synthesized by the coprecipitation method into an ITO sintered compact (refer patent document 5 etc.), and similarly, the wet synthesis method of ITO powder for obtaining a high density sintered compact is proposed (patent documents 6-6). 9, etc.).

However, the sputtering target can still obtain a high-density sintered body relatively easily without being strongly bound by the manufacturing method of the ITO powder and without highly controlling the sintering conditions and the like. There are many wishes for a manufacturing method.

[Patent Document 1] Japanese Patent Application Laid-Open No. 62-21751

[Patent Document 2] Japanese Patent Application Laid-Open No. 5-193939

[Patent Document 3] Japanese Unexamined Patent Publication No. 6-191846

[Patent Document 4] Japanese Patent Application Laid-Open No. 2001-261336

[Patent Document 5] Japanese Patent Application Laid-Open No. 62-21751

[Patent Document 6] Japanese Patent Application Laid-Open No. 9-221322

[Patent Document 7] Japanese Patent Application Laid-Open No. 2000-281337

[Patent Document 8] Japanese Patent Application Laid-Open No. 2001-172018

[Patent Document 9] Japanese Unexamined Patent Publication No. 2002-68744

In view of such circumstances, the present invention has an object to provide a method for producing a sputtering target, which can extend the life of the target and obtain a high-density sputtering target.

The 1st aspect of this invention which solves the said subject is a raw material which calcinates at least an indium oxide powder at 1100 degreeC-1300 degreeC, when mixing and baking the raw material containing an indium oxide powder and a tin oxide powder, and manufacturing a sputtering target. A mixed powder of is prepared, and the mixed powder is calcined at a temperature higher than or equal to 150 ° C. from the calcined temperature.

In this first aspect, at least the indium oxide powder is calcined at a predetermined temperature to significantly reduce the carbon content in the raw material, and the mixed powder is calcined at a predetermined temperature higher than the calcining temperature, so that high density and long target life are sputtered. Can be targeted.

According to a second aspect of the present invention, in the first aspect, the carbon content after calcination of the indium oxide powder is set to 50 ppm or less.

In this 2nd aspect, the target life after baking can be reliably improved by making the carbon content of the indium oxide powder after calcination into 50 ppm or less.

According to a third aspect of the present invention, in the first or second aspect, calcination of the indium oxide is performed so that a subsequent BET specific surface area is 0.8 to ⁴ m ² / g.

In this third aspect, by calcining the BET specific surface area to be within a predetermined range, the target density after firing can be improved and the target life can be reliably improved.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the treatment is performed to avoid contact between the raw material and the carbon dioxide gas during the calcination and after the calcination until the mixed powder is calcined. It is in the manufacturing method of the sputtering target made into.

In this fourth aspect, the carbon concentration in the calcined raw material can be reliably lowered by avoiding contact between the raw material and carbon dioxide gas.

The 5th aspect of this invention is a manufacturing method of the sputtering target characterized by the density | concentration after baking in any one of 1st-4 which is 99% or more.

In this fifth aspect, the target life can be reliably improved by setting the density of the sputtering target to 99% or more.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the tin-containing amount is 2.3 to 45% by mass in terms of SnO ₂ , and the method for producing a sputtering target according to the present invention is characterized in that the tin-containing amount is 2.3 to 45 mass%.

In this sixth aspect, the tin content can form a thin film having desired conductivity in a predetermined range.

(The best form to carry out invention)

In the method for producing a sputtering target of the present invention, when a raw material containing indium oxide powder and tin oxide powder is mixed and calcined to produce a sputtering target, at least the indium oxide powder is calcined at 1100 ° C to 1300 ° C, and then the mixed powder Is fired at a temperature higher than 150 ° C. from the calcined temperature.

In the method of the present invention, at least indium oxide powder is calcined in the raw material in order to reduce the carbon content contained in the indium oxide powder, and in order to effectively reduce the carbon content, 1100 ° C to 1300 ° C, preferably It is necessary to calcinate at 1150-1300 degreeC. Even if calcined at a lower temperature than this, carbon is not reduced because it is chemically adsorbed to the raw material powder. On the other hand, when calcined at a higher temperature than this, the carbon content is reduced, but problems occur in the firing process. In other words, after calcination, firing at a high temperature of 150 ° C. or higher than the calcination temperature yields a high-density sputtering target. When calcining at a temperature higher than 1300 ° C., the BET specific surface area becomes smaller than a predetermined range, and thus a high density target. This may not be obtained.

From this point of view, in the method of the present invention, it is preferable to calcinate at 1100 ° C to 1300 ° C, preferably 1150 ° C to 1300 ° C.

Further, a problem in the production of the sputtering target is carbon chemisorbed on the indium oxide powder, and carbon is hardly adsorbed on the tin oxide, which is not a problem. Therefore, in the method of the present invention, "calcination of at least indium oxide powder at 1100 DEG C to 1300 DEG C as a mixed powder of raw materials" means that at least the indium oxide powder should be calcined, and the tin oxide powder does not necessarily need to be calcined. to be. That is, in the case where indium oxide powder and tin oxide are used, at least only the indium oxide powder may be calcined, but of course, it may be calcined in a mixed state. In addition, a mixed powder obtained by adding indium oxide powder and tin oxide powder in addition to indium oxide-tin oxide powder (ITO powder) may be used. In ITO powder, since tin is dissolved in indium oxide, there is a problem in terms of carbon adsorption. It does not necessarily need to be calcined, but of course, it may be calcined.

In the method of the present invention, the carbon content in the calcined indium oxide powder as described above is preferably 50 ppm or less, preferably 20 ppm or less, particularly preferably 10 ppm or less. The carbon contained in the raw material powder affects the target life, as will be described later. The sputtering target obtained by sintering the raw material powder containing more than 50 ppm of carbon has a significantly shorter target life. Here, if the sputtering target is made of a raw material powder having a carbon content of more than 50 ppm, the metal oxide is reduced by carbon, and thus the metal part is confirmed in the target. However, when the raw material powder having a carbon content of 50 ppm or less is used, such a metal is used. It was confirmed that no site was observed. In addition, the carbon content in the indium oxide powder can be measured using a carbon-sulfur measuring apparatus (for example, EMIA-2200 manufactured by Horiba Co., Ltd.). In addition, when calcining the mixed powder containing indium oxide powder, since all the carbon content measured is estimated to originate in indium oxide, the carbon content contained in an indium oxide powder can be calculated from content of an indium oxide powder. .

For this purpose, in the method of the present invention, it is preferable to perform the treatment so as to avoid contact between the raw material and carbon dioxide gas during calcination and after calcination until firing. This is for preventing carbon dioxide gas from adsorbing to the calcined indium oxide powder and increasing the carbon content.

Moreover, in the method of this invention, it is preferable to perform calcination of indium oxide powder so that a subsequent BET specific surface area may be 0.8-4 m <^2> / g. It is because a high-density sputtering target can be obtained at the time of baking by making BET specific surface area into this range.

In the method of the present invention, a mixed powder containing indium oxide calcined at a predetermined temperature as described above is calcined to form a sputtering target. At this time, the density after calcining is preferably 99% or more. This is because the denser the sputtering target, the better the target life.

The manufacturing method of the raw material used by such a method of this invention is not specifically limited, What is necessary is just to prepare the raw material which can obtain the sputtering target of a desired composition. In addition, when a raw material mixes and uses an indium oxide powder and tin oxide in a predetermined ratio, for example, when raw material may be calcined before mixing, it may be calcined after mixing, and when calcining and mixing, Similarly, at least the indium oxide powder may be calcined.

Here, the material of the sputtering target, it is preferred that the tin content so 2.3~45% by weight as SnO ₂ basis. The reason for this is that a thin film having desired conductivity can be formed. For example, a SnO ₂ solid solution of 2.3 mass% or more means that even at least tin content is 2.3 mass% in terms of SnO ₂ , on the other hand, when it exceeds 45 mass%, for example, when a thin film is formed as a sputtering target, SnO _{Since 2} precipitates and inhibits electroconductivity, both are undesirable.

Next, an example of the process of baking a raw material by the method of this invention and obtaining a sputtering target is demonstrated.

The mixed powder mixed with the raw materials is, for example, molded and fired using conventionally known various wet or dry methods.

As a dry method, a cold press method, a hot press method, etc. are mentioned. In the cold press method, ITO powder is filled into a molding die to form a molded product, and then fired and sintered under an atmospheric atmosphere or under an oxygen atmosphere. In the hot press method, ITO powder is directly sintered in a molding die.

As the wet method, for example, it is preferable to use a filtration molding method (see Japanese Patent Laid-Open No. 11-286002). This filtration molding method is a filtration type mold which consists of a non-aqueous material for depressurizing and draining water from a ceramic raw material slurry to obtain a molded body. The filtration molding method includes a lower mold for molding having one or more water discharge holes and a tube placed on the lower mold for molding. It consists of an aqueous filter and a molding die clamped from an upper surface side through a sealing material for sealing the filter, and is assembled to disassemble the lower mold, the molding die, the sealing member, and the filter, respectively. A slurry formed of a mixed powder, ion-exchanged water and an organic additive is prepared by using a filtration molding mold for depressurizing and draining water in the slurry from only the filter surface side, and the slurry is injected into the filtration molding mold, and the filter is The molded article was produced by depressurizing and draining moisture in the slurry only from the surface side. Joe is fired after degreasing.

In each method, the firing temperature is preferably 1300 to 1600 ° C, more preferably 1450 to 1600 ° C in the case of an ITO target. Thereafter, machining is carried out for forming and processing to a predetermined dimension and is targeted.

Generally, after shaping, the surface is ground to adjust the thickness and, in order to smooth the surface, some steps are polished. However, it is preferable to perform a predetermined surface treatment to remove microcracks. Do.

(Example)

Hereinafter, although this invention is demonstrated based on an Example, it is not limited to this.

(Example 1)

90 mass% of the indium oxide powder calcined the wet synthesized indium oxide powder at 1100 degreeC, and 10 mass% of the tin oxide powder calcined the wet synthesized tin oxide at 1050 degreeC similarly were used as the raw material powder of Example 1.

(Example 2)

90 mass% of the indium oxide powder calcined the wet synthesized indium oxide powder at 1150 degreeC, and 10 mass% of the tin oxide powder calcined the wet synthesized tin oxide at 1050 degreeC similarly were used as the raw material powder of Example 2.

(Example 3)

90 mass% of the indium oxide powder calcined the wet synthesized indium oxide powder at 1200 degreeC, and 10 mass% of the tin oxide powder calcined the wet synthesized tin oxide at 1050 degreeC similarly were used as the raw material powder of Example 3.

(Example 4)

90 mass% of the indium oxide powder calcined the wet synthesized indium oxide powder at 1250 degreeC, and 10 mass% of the tin oxide powder calcined the wet synthesized tin oxide at 1050 degreeC was made into the raw material powder of Example 4.

(Example 5)

90 mass% of the indium oxide powder calcined the wet synthesized indium oxide powder at 1300 degreeC, and 10 mass% of the tin oxide powder calcined the wet synthesized tin oxide at 1050 degreeC similarly were used as the raw material powder of Example 5.

(Comparative Example 1)

90 mass% of the indium oxide powder calcined the wet synthesized indium oxide powder at 1000 degreeC, and 10 mass% of the tin oxide powder calcined the wet synthesized tin oxide at 1000 degreeC similarly were used as the raw material powder of the comparative example 1.

(Test Example 1)

The carbon content in the indium oxide powder after calcination of each Example and the comparative example was measured using the carbon-sulfur measuring apparatus (EMI-2200 by Horiba Corporation). The results are shown in Table 1. Table 1 also shows the specific surface area of the indium oxide powder after calcining in the BET method.

Sample number After calcination of carbon content (ppm) After calcination of BET specific surface area (m ² / g) Example 1 50 3.6 Example 2 20 2.5 Example 3 20 1.8 Example 4 20 1.3 Example 5 10 0.8 Comparative Example 1 160 5.7

(Manufacture example 1)

The raw material of Example 1 was mixed and pulverized with a dry ball mill, it was further pulverized by a wet ball mill, it was made into a slurry, this slurry was poured into a filtration mold, and the water in a slurry was drained under reduced pressure only from the filter surface side, and a molded object was carried out. The produced and obtained ceramic molded object was dried and degreased. The relative density after degreasing | molding of this molded object was 67.7% of theoretical density 7.15.

This was baked at 1600 degreeC and the sputtering target which is a sintered compact was obtained. This relative density was 99.9%.

(Manufacture example 2)

The raw material of Example 4 was mixed and pulverized with a dry ball mill, it was further pulverized by a wet ball mill, it was made into a slurry, this slurry was poured into a filtration type mold, the water in a slurry was drained under reduced pressure only from the filter surface side, and a molded object was carried out. Was produced and the obtained ceramic molding was dried and degreased. The relative density after degreasing | molding of this molded object was 68.0% of theoretical density 7.15.

This was baked at 1600 degreeC and the sputtering target which is a sintered compact was obtained. This relative density was 99.0%.

Comparative Example 1

The raw material of the comparative example 1 was mixed and disintegrated with the dry ball mill, it was further disintegrated by the wet ball mill, it was made into a slurry, this slurry was inject | poured into a filtration molding die, the water in a slurry was drained under reduced pressure only from the filter surface side, and a molded object was carried out. The produced and obtained ceramic molded object was dried and degreased. The relative density after degreasing | molding of this molded object was 60.0% of theoretical density 7.15.

This was baked at 1600 degreeC and the sputtering target which is a sintered compact was obtained. This relative density was 99.0%.

(Test Example 2)

Arcing characteristics were measured using the sputtering targets of Production Examples 1 and 2 and Comparative Production Example 1. That is, it sputter | spattered continuously with the DC magnetron sputter under the following conditions, and measured 50 Counts life. Here, the 50 Counts life refers to the amount of input power (Wh / cm ² ) when the accumulated arcing number reaches 50 times, except for the initial arc number up to the input power amount 10 Wh / cm ² from the start of each target use. Incidentally, the arcing was detected by an arc detection device (MAM Genesis) manufactured by Landmark Technology. The results are shown in Table 2 below.

As a result, it can be seen that the sputtering target using the indium oxide powder calcined at a predetermined temperature by the method of the present invention has superior arcing characteristics and a long target life as compared with the comparative production example using the indium oxide powder having a low calcining temperature. there was.

(Sputtering condition)

Target dimension: diameter 6 inch, thickness 6mm

Sputter method: DC magnetron sputter

Exhaust System: Rotary Pump + Clio Pump

Reach vacuum level: 3.0 × 10 ^-7 [Torr]

Ar pressure: 3.0 × 10 ^-3 [Torr]

Oxygen partial pressure: 3.0 × 10 ^-5 [Torr]

Sputter Power: 300W (Power Density 1.6W / cm ² )

50 Counts Life (Watt · hour / cm ² ) Preparation Example 1 75 Preparation Example 2 84 Comparative Production Example 1 29

As described above, in the present invention, a sputtering target having a long target life can be produced by calcining the raw material powder at a predetermined temperature and then firing temperature in a predetermined temperature range.

Claims (9)

When a raw material comprising an indium oxide powder and a tin oxide powder is mixed and calcined to produce a sputtering target, indium oxide having a carbon content of 50 ppm or less obtained by calcining the indium oxide powder at 1100 ° C to 1300 ° C is used as a mixed powder of the powder raw material. And a mixed powder is fired at a temperature higher than 150 ° C. from the calcined temperature. delete The method for producing a sputtering target according to claim 1, wherein the BET specific surface area after calcination of said indium oxide is 0.8 to ⁴ m ² / g. The method for producing a sputtering target according to claim 1, wherein the treatment is performed to avoid contact between the raw material and carbon dioxide gas during the calcination and during the calcination until the mixed powder is calcined. 4. The method for producing a sputtering target according to claim 3, wherein the treatment is performed to avoid contact between the raw material and the carbon dioxide gas during the calcination and during the calcination until the mixed powder is calcined. The method for producing a sputtering target according to claim 1, wherein the density after firing is 99% or more. The method for producing a sputtering target according to any one of claims 3 to 5, wherein the density after firing is 99% or more. The method for producing a sputtering target according to any one of claims 1, 3, 4, 5 or 6, wherein the tin content is 2.3 to 45 mass% in terms of SnO ₂ . The method for producing a sputtering target according to claim 7, wherein the tin content is 2.3 to 45 mass% in terms of SnO ₂ .