KR101259713B1 - Method for producing ito sintered body and method for producing ito sputtering target - Google Patents

Abstract

Provided are a method for producing an ITO sintered compact and a method for producing an ITO sputtering target capable of producing a high quality sintered compact at low cost.
In the manufacturing method of the ITO sintered compact which concerns on one Embodiment of this invention, the sintered group group which has indium oxide and tin oxide as a main component is crushed while stirring in a container, and the 1st ITO powder which has a 1st average particle diameter is produced. It includes a process to make. By crushing the first ITO powder by a media stirring mill or a jet mill, a second ITO powder having a second average particle diameter smaller than the first average particle diameter is produced. By mixing the indium oxide powder and the tin oxide powder with the second ITO powder, and pulverizing the mixed powder, a third ITO powder having a third average particle diameter smaller than the second average particle diameter is produced. The molded body is produced by casting the slurry containing the third ITO powder into the formwork, and then sintered.

Description

METHODS FOR PRODUCING ITO SINTERED BODY AND METHOD FOR PRODUCING ITO SPUTTERING TARGET}

This invention relates to the manufacturing method of the ITO sintered compact used as a sputtering target, and the manufacturing method of an ITO sputtering target, for example.

BACKGROUND ART In the field of manufacturing flat panel displays and solar power modules, an ITO film mainly containing indium oxide and tin oxide as a transparent conductive film is widely used. The ITO film is formed by vacuum deposition, sputtering, or the like. In the sputtering method, a sputtering target composed of ITO is used. As the ITO target, a sintered body of a mixed powder of indium oxide and tin oxide is widely used. In particular, in recent years, in order to reduce manufacturing cost, the recycling of the used ITO target is examined (for example, refer patent documents 1-3).

Patent Literature 1 describes a method for producing an ITO sintered body in which a surface deposit of an ITO target after use in sputtering film formation is removed, which is then powdered by autogenous pulverization, and the powder is then sintered.

In Patent Document 2, ITO crushed scraped ITO sintered compact into granules of 0.5 mm or less, and then ITO granules and a powder made of indium, tin and oxygen are mixed, followed by molding and sintering. A regeneration method of a sintered compact is disclosed.

In Patent Document 3, the ITO recycled powder is heat-treated, molded according to slip casting using a powder whose specific surface area is adjusted in the range of 2.5 to 7.0 m ² / g, and the obtained molded product is dried, followed by oxygen The manufacturing method of the ITO sintered compact which bakes in an atmosphere is described.

Patent Document 1: Japanese Patent Laid-Open No. 7-316798 (paragraph [0015]) Patent Document 2: Japanese Patent Application Laid-Open No. 11-100253 (paragraph [0009]) Patent Document 3: Japanese Patent Application Laid-Open No. 11-228219 (paragraph [0005])

In order to realize stable sputter film formation and high quality thin film formation, the sputtering target requires densification and uniformity of the structure. For this reason, it is essential to refine the raw material powder to improve the sintered density. However, at the time of manufacture of the sintered compact which uses the used target as a raw material, cost becomes high for refinement | miniaturization of the sintered compact used as a raw material, and there exists a problem that it is difficult to manufacture a high-density and high homogeneity ITO sintered compact at low cost.

In view of the above circumstances, an object of the present invention is to provide a manufacturing method of an ITO sintered compact and a manufacturing method of an ITO sputtering target which can manufacture a high quality sintered compact at low cost.

MEANS TO SOLVE THE PROBLEM In order to achieve the said objective, the manufacturing method of the ITO sintered compact which concerns on one form of this invention breaks | pulverizes the sintered piece group which has indium oxide and tin oxide as a main component, stirring in a container, and is 1st. A process for producing a first ITO powder having an average particle diameter is included. By crushing the first ITO powder by a media mixing mill or a jet mill, a second ITO powder having a second average particle diameter smaller than the first average particle diameter is produced. By mixing the indium oxide powder and the tin oxide powder with the second ITO powder, and pulverizing the mixed powder, a third ITO powder having a third average particle diameter smaller than the second average particle diameter is produced. After the molded article is produced by casting a slurry containing the third ITO powder into a die, the molded article is sintered.

Moreover, in order to achieve the said objective, the manufacturing method of the ITO sputtering target which concerns on one form of this invention crushes the sintered group group which has indium oxide and tin oxide as a main component, stirring in a container, and a 1st average particle A process for producing a first ITO powder having a diameter is included. By crushing the first ITO powder by a media stirring mill or a jet mill, a second ITO powder having a second average particle diameter smaller than the first average particle diameter is produced. By mixing the indium oxide powder and the tin oxide powder with the second ITO powder, and pulverizing the mixed powder, a third ITO powder having a third average particle diameter smaller than the second average particle diameter is produced. After the molded article is produced by casting the slurry containing the third ITO powder into the die, the molded article is sintered.

BRIEF DESCRIPTION OF THE DRAWINGS The process flow which shows the manufacturing method of the ITO sintered compact which concerns on embodiment of this invention.
It is a schematic diagram explaining the separation process of the target which complete | finished use in embodiment of this invention.
It is a schematic diagram explaining the preparation process of the sintered piece in embodiment of this invention.
It is a schematic diagram explaining the manufacturing process of the 1st ITO powder in embodiment of this invention.
It is a schematic diagram explaining the manufacturing process of the 3rd ITO powder and slurry containing the same in embodiment of this invention.
Fig. 6 is a schematic view of a molding die used in the molding step in the embodiment of the present invention, (A) is a side cross-sectional view, and (B) is a plan view of the form body.
It is a schematic diagram of the sintered compact produced by embodiment of this invention.

In the manufacturing method of the ITO sintered compact which concerns on one Embodiment of this invention, the sintered group group which has indium oxide and tin oxide as a main component is crushed while stirring in a container, and the 1st ITO powder which has a 1st average particle diameter is produced. It includes a process to make. The first ITO powder is crushed to a size having a first average particle diameter (for example, 2 μm) by the collision action between the sintered pieces. The said sintered piece group can be made into the small piece of the fixed or irregular shaped ITO sintered material, or the divided piece which divided | segmented the sintered material into suitable shape. Examples of the sintered material include waste materials inevitably generated during the production of the ITO sintered product, finished sintered products, and the like, and are typically ITO sputtering targets.

Here, in this specification, an "average particle diameter" means the value of 50% of the integrated% of the particle size distribution measured by the laser diffraction scattering method. In addition, the value of the average particle diameter used the measured value by Nikkiso Corporation laser diffraction scattering particle size analyzer (MT3000II).

The said 1st ITO powder is produced by crushing the said sintered piece group in a resin container. Thereby, for example, mixing of impurities into the powder can be suppressed as compared with the case of producing the ITO powder in the metal container. Of course, when the resin container is used, the resin component may be mixed in the powder, but the resin component can be lost in the degreasing step or the sintering step.

Next, the first ITO powder is pulverized by a media stirring mill or a jet mill to produce a second ITO powder having a second average particle diameter (for example, 0.6 µm). Thereby, it becomes possible to produce finer ITO powder from the said sintered piece.

As a medium stirring mill, a vibratory ball mill, a rod mill, etc. can be illustrated. The medium stirring mill or the jet mill may be wet or dry. In the case of using a medium agitating mill, mixing of the impurity into the powder can be effectively suppressed by employing a resin coat applied to the surface of the ball or rod made of the stirring medium. In this embodiment, a vibrating ball mill is used suitably as a medium stirring mill. As a jet mill, a wet jet mill is very suitable.

Subsequently, indium oxide powder and tin oxide powder are mixed with the second ITO powder, and the mixed powder is pulverized to obtain a third average particle diameter smaller than the second average particle diameter (for example, 0.20 µm to 0.30 µm). The third ITO powder having is produced. Although unused powder is used as an indium oxide powder and tin oxide powder mixed with 2nd ITO powder, respectively, it is not limited to this. The average particle diameter of the said indium oxide powder and tin oxide powder is not specifically limited, A suitable particle diameter can be employ | adopted.

The third ITO powder can be produced using a medium stirring mill. Thereby, the ITO powder which has a comparatively fine average particle diameter can be manufactured easily. As a medium stirring mill, although a ball mill, a rod mill, etc. are applicable, a vibrating ball mill is very suitable.

By setting the average particle diameter (third average particle diameter) of the third ITO powder to 0.20 µm or more and 0.30 µm or less, a high quality ITO sintered body having a relative density of 99.8% or more and excellent in uniformity of composition can be produced. .

The mixing ratio of the second ITO powder in the third ITO powder may be 10% by weight or more and 40% by weight or less. Thereby, the material cost of an ITO sintered compact can be reduced effectively. Moreover, when the mixing ratio of 2nd ITO powder exceeds 40 weight%, there exists a possibility that the average particle diameter made into the objective of 3rd ITO powder, or the relative density and composition made into the objective of an ITO sintered compact may not be obtained. Moreover, when the mixing ratio of 2nd ITO powder is less than 10 weight%, the effect of reducing the material cost of an ITO sintered compact becomes low.

Next, the molded object is produced by casting the slurry containing the said 3rd ITO powder to the die, and the target ITO sintered compact is produced by sintering this molded object. The slip injection molding method is a method in which a low viscosity slurry (slip) is poured into an absorbent mold such as a gypsum mold, a powder deposition layer is formed on the inner wall of the mold chamber of the mold, dried, and then taken out of the mold to obtain a molded body. By adopting the slip injection molding method, a molded article can be produced at a relatively low cost.

According to the manufacturing method of the said ITO sintered compact, since the crushed powder of an existing sintered piece is used as a part of raw material of a sintered compact, raw material cost can be reduced. Moreover, since the crushed powder of the said sintered piece is refine | miniaturized step by step, refinement | miniaturization of a sintered particle can be achieved without the significant increase of a process water or a special process, and it becomes possible to manufacture a high quality sintered compact at comparatively low cost. . Therefore, a high quality ITO sputtering target can be manufactured by passing through the above process.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing explaining the manufacturing method of the ITO sintered compact by embodiment of this invention. 2-7 is a schematic diagram explaining each process. In this embodiment, the sintered piece preparation process (step 1), the coarse grinding process (step 2), the fine grinding process (step 3), the mixed fine grinding process (step 4), and the slurry adjustment process (step 5) And a molding step (step 6) and a sintering step (step 7).

[Sinter Piece Preparation Process]

In this step, a sintered piece that becomes part of the raw material is prepared. Here, as shown in FIG.2 and FIG.3, the target sintered piece 2a is produced by dividing the used ITO sputtering target 2 into a suitable shape and size. The sputtering target 2 is used in a form separated from the baking plate 1 supporting it. The separated sputtering target 2 is washed with an acid in order to remove lead materials such as In and impurities adhering to the surface, and then a sintered piece 2a is produced. As for the sputtering target 2 used, what has the same composition as the new ITO sintered compact manufactured as this is used.

[Crushing Mill]

This process accommodates the produced appropriate amount of sintered pieces 2a in the resin container 3a (FIG. 4 (A)), rotates the container 3a, and breaks these groups of sintered pieces by impact ( 4 (B)). As the resin container 3a, a container for grinding used in a ball mill, a rod mill, or the like can be used. This crushing step is performed by adding an appropriate amount of pure water into the container 3a. By this process, 1st ITO powder P1 which has a 1st average particle diameter is produced. 1st average particle diameter is not specifically limited, For example, it can be set to 2 micrometers. In the illustrated example, the first ITO powder P1 is exaggerated slightly.

By producing the first ITO powder P1 in the resin container 3a, the incorporation of impurities into the powder can be suppressed as compared with the case where the ITO powder is produced in, for example, a metal container. Of course, when the resin container is used, the resin component may be mixed in the powder, but it is possible to lose the resin component in the degreasing step or the sintering step.

[Grinding process]

In this step, the first ITO powder P1 is pulverized using a vibrating ball mill or a wet jet mill to produce a second ITO powder P2 having a second average particle diameter. Thereby, 1st ITO powder can be refined | miniaturized more. The magnitude | size of a 2nd average particle diameter is not specifically limited, For example, it can be 0.6 micrometer.

Even in this fine grinding step, the second ITO powder is pulverized in the resin container. In the case of using a vibrating ball mill, a ball having a resin coated on its surface is used as a stirring medium. Thereby, it becomes possible to suppress mixing of dissimilar metals into the second ITO powder. This pulverization process can be performed by adding pure water and a suitable dispersing agent to the said container. The obtained 2nd ITO powder is dried as needed.

[Mixed Grinding Process]

In this step, as shown in Figs. 5A and 5B, indium oxide (In ₂ O ₃ ) powder P2a and tin oxide (SnO ₂ ) powder P2b are mixed with the second ITO powder P2, and the By grinding the mixed powder, third ITO powder P3 having a third average particle diameter is produced. By setting the average particle diameter of the third ITO powder P3 to 0.20 µm or more and 0.30 µm or less, a high quality ITO sintered body having a relative density of 99.8% or more and excellent in uniformity of composition can be produced.

Unused powder is used for both indium oxide powder P2a and tin oxide powder P2b mixed with 2nd ITO powder P2. The raw material cost can be reduced by combining raw material powder produced from a ready-made sintered piece and unused raw material powder. In addition, it becomes possible to recycle the finished material such as a sputtering target with good efficiency.

In this embodiment, indium oxide powder P2a of 0.9 micrometer in average particle diameter, and tin oxide powder P2b of 1.3 micrometer in average particle diameter are used. The average particle diameter of indium oxide powder P2a and tin oxide powder P2b is not limited to the above-mentioned example, For example, the thing of the size equivalent to or less than the average particle diameter of 2nd ITO powder P2 can be used.

The addition amount of indium oxide powder P2a and tin oxide powder P2b can be suitably adjusted according to the component composition of 2nd ITO powder P2, and the component composition of the target ITO sintered compact. In this embodiment, indium oxide powder P2a and tin oxide powder P2b are mixed with 2nd ITO powder P2 so that it may become 9: 1 by weight ratio. Moreover, the mixing ratio of 2nd ITO powder P2 in 3rd ITO powder P3 can be 10 weight% or more and 40 weight% or less. Thereby, the material cost of an ITO sintered compact can be reduced effectively.

Also in this mixing step, the third ITO powder P3 is pulverized in the resin container 3b. In the case of using a ball mill, a ball having a resin coating applied to its surface is used as a stirring medium. Thereby, it becomes possible to suppress mixing of the dissimilar metal into 3rd ITO powder P3. This mixing process can be performed by adding pure water and a suitable dispersing agent to the container 3b.

[Slurry Adjustment Process]

This process adjusts the slurry S containing 3rd ITO powder P3 (FIG. 5 (B)). Slurry S is a liquid substance which suspended 3rd ITO powder P3 in pure water, and is adjusted so that the density | concentration of ITO powder P3 in a slurry may be 70%-80%, for example. The adjustment process of this slurry S may be contained in the said mixing process, and in this case, slurry S is adjusted in the last stage of the said mixing process.

[Molding process]

A molding process obtains a molded object by filling slurry S in the shaping | molding die 4 shown to FIG. 6 (A), (B). The shaping | molding die 4 is comprised from the absorptive material, such as gypsum, for example, and has the cover 4b as the main body 4a.

The main body 4a is provided with the internal space 4c and the injection port 4d which communicates with this internal space. The illustrated configuration is an example, and the shape of the internal space 4c, the position of the injection port 4d, and the like can be appropriately set. The slurry S is filled into the internal space 4c at a predetermined pressure through the injection port 4d, and the state is maintained for a predetermined time. Thereby, the moisture in the slurry S is absorbed by the shaping | molding die 4, and ITO powder P3 is shape | molded at high density by attaching in the formwork. By adopting such a slip injection molding method for producing a molded article, a molded article can be produced at a relatively low cost.

The shaping | molding die 4 is formed by making gypsum slurry into a raw material, shape | molding it, and drying. The ratio of water which is a solvent of a gypsum slurry can be 50 weight% or more and 65 weight% or less. When the solvent in the gypsum slurry is excessively large (for example, more than 65% by weight), the amount of liquid absorbed by the mold is increased, but the average pore diameter of the mold is also increased, so that the absorption force due to capillary phenomenon is reduced. As a result, at the time of shaping | molding at the time of manufacturing a molded object, the drainage efficiency of the water which is a solvent in a slurry worsens, and it requires long time for shaping | molding. If the amount of solvent in the gypsum slurry is small (e.g., less than 50% by weight), the amount of liquid absorbed in the molding die is small, so that the water in the slurry cannot be sufficiently drained during molding at the time of forming the molded body. This makes it difficult to produce a satisfactory molded body.

The produced molded object is dried through a drying process. The drying step can be performed in a drying chamber maintained at a predetermined temperature. After drying, you may perform the degreasing process of a molded object as needed. Thereby, the resin component contained in a molded object is removed, and the purity of a molded object can be improved.

[Sintering process]

A sintering process sinters the obtained molded object, and produces the target ITO sintered compact Sc. Sintering is performed, for example in air | atmosphere, and sintering temperature can be 1500 degreeC-1650 degreeC, for example.

The ITO sintered compact Sc produced as mentioned above has a relative density of 99.8% or more and an average grain size of 5 micrometers or less. After manufacture of the sintered compact Sc, an ITO sputtering target is produced by cutting or grinding it to a predetermined shape.

The relative density and grain size of the sintered compact Sc are mainly determined by the average particle diameter of the ITO powder P3 in the slurry, and the average particle diameter of the ITO powder P3 is 0.2 µm to 0.3 µm to stably obtain the sintered compact of all the above-described characteristics. It becomes possible. Moreover, since the crushed powder P1 of the sintered piece 2a is refine | miniaturized step by step, refinement | miniaturization of a sintered particle can be achieved without requiring a significant increase of a process water or a special process. Therefore, according to this embodiment, a high-density sintered compact with fine grains and uniform structure can be produced at low cost.

The sputtering target produced as mentioned above can suppress generation | occurrence | production of a nodule, and can realize stable sputter film deposition.

(Example 1)

The used ITO target was heated to 200 ° C. to be peeled off from the baking plate, and it was immersed in 50% dilute acid for 24 hours to remove the bonding solder for adhering to the surface. The ITO target was divided into appropriate sizes to prepare a target piece as a sintered piece. 200 kg of these target pieces were put into the resin container of the capacity of 300 liters with 20 liters of pure water, and each target piece was crushed by stirring the container for 24 hours at the rotation speed of 35 rpm. Thereafter, the crushed powder was classified and the powder of 100 micrometers or less was collected, and the copper powder was dried at 200 degreeC for 24 hours, and this was set as the 1st ITO powder. The average particle diameter of the obtained 1st ITO powder was 2 micrometers (maximum value 80 micrometers).

Next, the 1st ITO powder was grind | pulverized using the vibrating ball mill, and the 2nd ITO powder was produced. More specifically, 9 kg of the first ITO powder and 50 kg of a 10 mm diameter ball (stirring medium) coated with a resin on a surface of a 50-liter resin container were placed, and 10 liters of pure water and a carboxylic acid system were added. 180 milliliters of a dispersant was added, and the 1st ITO powder was grind | pulverized on condition of 5 mm and amplitude of 8 mm. The average particle diameter of the obtained 2nd ITO powder was 0.6 micrometers (maximum value 5 micrometers).

After drying the 2nd ITO powder at 200 degreeC for 24 hours, it disintegrated by the spin mill. In a 200-liter resin container, 30 wt% (42 kg) of this second ITO powder, 70 wt% of unused raw material powder (88.2 kg of indium oxide powder, 9.8 kg of tin oxide powder), and 10 mm in diameter 272 kg of zirconia balls (stirring medium) were added, 37.4 liters of pure water and 2.31 liters of carboxylic acid dispersant were added, and the mixture was mixed for 84 hours. This produced the slurry containing the 3rd ITO powder whose average particle diameter is 0.25 micrometer (maximum value 2 micrometers). The slurry had a concentration of 78% and a viscosity of 200 cps. 1 weight% of carboxylic acid binders were added to the prepared slurry, and the slurry was degassed under vacuum at 20 rpm for 30 minutes.

A gypsum mold having a double-sided skin structure capable of producing a molded article having a length of 415 mm, a width of 780 mm, and a thickness of 10.5 mm was prepared. In this gypsum mold, the slurry was poured at 3 kg / cm <^2> of shaping | molding pressure by adjusting the injection valve of a defoaming machine, and it shape | molded. Molding time was 80 minutes. The obtained molded product was naturally dried in a drying chamber in a 30 ° C atmosphere for 6 days to obtain a molded product having a length of 380 mm, a width of 780 mm, and a thickness of 10.5 mm. Thereafter, the molded body was degreased under heating conditions at 600 ° C. for 3 hours in the air. After degreasing, the molded body was sintered. Sintering temperature was 1600 degreeC and sintering time was 8 hours. Sintering atmosphere was made into oxygen atmosphere, and oxygen introduction amount was 200 liters per minute.

The obtained sintered compact was 310 mm in length, 620 mm in width, and 8.5 mm in thickness. Both surfaces of this sintered compact were ground and the cross section was cut | disconnected, and it was finished to length 300mm, width 610mm, and thickness 7mm. The average grain diameter of the sintered compact was 4.2 µm and the relative density was 99.8%. This sintered compact was reprocessed to 127 mm long, 381 mm wide, and 6 mm thick, and bonded by the copper baking plate, and the ITO sputtering target was produced.

The target was embedded in a sputtering apparatus and sputtered at 100 kWh. It was confirmed that no generation of nodules to the target surface occurred. In addition, the resistance value of the formed ITO film (200 nm) was measured using the sputtering target, which was 0.2 × 10 −3 Ω cm. As a result, it was confirmed that the ITO film had a resistance value equivalent to that of the ITO film formed by using the ITO target sintered with only unused raw material powder.

(Example 2)

The used ITO target was heated to 200 ° C. to be peeled from the baking plate, and it was immersed in 50% dilute acid for 24 hours to remove the bonding solder for adhering to the surface. The ITO target was divided into appropriate sizes to prepare a target piece as a sintered piece. 200 kg of these target pieces were put into the resin container of the capacity of 300 liters with 20 liters of pure water, and each target piece was crushed by stirring the container for 24 hours at the rotation speed of 35 rpm. Thereafter, the crushed powder was classified to recover a powder having a thickness of 100 μm or less, which was used as the first ITO powder. The average particle diameter of the obtained 1st ITO powder was 2 micrometers (maximum value 80 micrometers).

Next, the 1st ITO powder was grind | pulverized using the vibrating ball mill, and the 2nd ITO powder was produced. More specifically, in a 50-liter resin container, 50 kg of a 10 mm diameter ball (stirred medium) resin-coated with 9 kg of the first ITO powder was put, and 10 liters of pure water and a carboxylic acid-based dispersant were added. 180 milliliters were added, and the 1st ITO powder was grind | pulverized on condition of 5 mm and amplitude of 8 mm. The average particle diameter of the obtained 2nd ITO powder was 0.6 micrometers (maximum value 5 micrometers).

The second ITO powder was dried at 200 ° C. for 24 hours and then disintegrated with a spin mill. And 10 weight% (14 kg) of this 2 ITO powders, 90 weight% of unused raw material powders (113.4 kg of indium oxide powders, 12.6 kg of tin oxide powders), and 10 mm diameter in the resin container of a capacity of 200 liters 272 kg of zirconia balls (stirring medium) were added, 37.4 liters of pure water and 2.31 liters of carboxylic acid dispersant were added, and the mixture was mixed for 84 hours. This produced the slurry containing the 3rd ITO powder whose average particle diameter is 0.25 micrometer (maximum value 2 micrometers). The slurry had a concentration of 78% and a viscosity of 200 cps. 1 weight% of carboxylic acid binders were added to the prepared slurry, and the slurry was degassed under vacuum at 20 rpm for 30 minutes.

The plaster mold of the double-sided structure which can manufacture the molded object of 415 mm in length, 780 mm in width, and 17 mm in thickness was prepared. In this gypsum mold, the slurry was poured at 3 kg / cm <^2> of shaping | molding pressure by adjusting the injection valve of a defoaming machine, and it shape | molded. Molding time was 80 minutes. The obtained molded object was naturally dried in a drying chamber in a 30 ° C atmosphere for 6 days to obtain a molded product having a length of 380 mm, a width of 780 mm, and a thickness of 17 mm. Thereafter, the molded body was degreased under heating conditions at 600 ° C. for 3 hours in the air. After degreasing, the molded body was sintered. Sintering temperature was 1600 degreeC and sintering time was 8 hours. Sintering atmosphere was made into oxygen atmosphere, and oxygen introduction amount was 200 liters per minute.

The obtained sintered compact was 310 mm long, 610 mm wide, and thickness 15 mm. Both surfaces of this sintered compact were ground and the cross section was cut | disconnected, and it was finished to length 300mm, width 610mm, and thickness 7mm. The average grain diameter of the sintered compact was 4.3 µm and the relative density was 99.9%. This sintered compact was reprocessed to 127 mm long, 381 mm wide, and 6 mm thick, and bonded to the copper baking plate, and the ITO sputtering target was produced.

The target was embedded in the sputtering apparatus and sputtered at 100 kWh, and it was confirmed that no generation of nodules to the target surface occurred. Furthermore, the resistance value of the ITO film (200 nm) formed using this sputtering target was measured, and was 0.2x10 <-3> ohm-cm. As a result, it was confirmed that the ITO film had a resistance value equivalent to that of the ITO film formed by using the ITO target sintered with only unused raw material powder.

(Example 3)

The used ITO target was heated to 200 ° C. to be peeled off from the baking plate, and it was immersed in 50% dilute acid for 24 hours to remove the bonding solder for adhering to the surface. The ITO target was divided into appropriate sizes to prepare a target piece as a sintered piece. 200 kg of these target pieces were put into the resin container of the capacity of 300 liters with 20 liters of pure water, and each target piece was crushed by stirring the container for 24 hours at the rotation speed of 35 rpm. Thereafter, the crushed powder was classified to recover a powder having a thickness of 100 μm or less, which was used as the first ITO powder. The average particle diameter of the obtained 1st ITO powder was 2 micrometers (maximum value 80 micrometers).

Next, the 1st ITO powder was grind | pulverized using the vibrating ball mill, and the 2nd ITO powder was produced. More specifically, 50 kg of a 10 mm diameter ball (stirred medium) resin-coated with 9 kg of the first ITO powder was put in a 50-liter resin container, and further, 10 liters of pure water and a carboxylic acid dispersant. 180 milliliters were added, and the 1st ITO powder was grind | pulverized on condition of 5 mm and amplitude of 8 mm. The average particle diameter of the obtained 2nd ITO powder was 0.6 micrometers (maximum value 5 micrometers).

The second ITO powder was dried at 200 ° C. for 24 hours and then disintegrated with a spin mill. And 40 weight% (56 kg) of this 2 ITO powders, 60 weight% of unused raw material powders (75.6 kg of indium oxide powders, 8.4 kg of tin oxide powders), and diameter 10mm in the resin container of capacity 200 liters 272 kg of zirconia ball (stirring medium) was added, 37.4 liters of pure water and 2.31 liters of carboxylic acid-based dispersant were added, and the mixture was mixed for 84 hours. This produced the slurry containing the 3rd ITO powder whose average particle diameter is 0.25 micrometer (maximum value 2 micrometers). The slurry had a concentration of 78% and a viscosity of 200 cps. 1 weight% of carboxylic acid binders were added to the prepared slurry, and the slurry was degassed under vacuum at 20 rpm for 30 minutes.

The plaster mold of the double-sided structure which can manufacture the molded object of 415 mm in length, 780 mm in width, and 17 mm in thickness was prepared. In this gypsum mold, the slurry was poured at 3 kg / cm <^2> of shaping | molding pressure by adjusting the injection valve of a defoaming machine, and it shape | molded. Molding time was 80 minutes. The obtained molded object was naturally dried in a drying chamber at 30 ° C. for 6 days to obtain a molded product having a length of 380 mm, a width of 780 mm, and a thickness of 17 mm. Thereafter, the molded body was degreased under heating conditions at 600 ° C. for 3 hours in the air. After degreasing, the molded body was sintered. Sintering temperature was 1600 degreeC and sintering time was 8 hours. Sintering atmosphere was made into oxygen atmosphere, and oxygen introduction amount was 200 liters per minute.

The obtained sintered compact was 310 mm long, 610 mm wide, and thickness 15 mm. Both surfaces of this sintered compact were ground and the cross section was cut | disconnected, and it finished by 300 mm length, 610 mm width, and 7 mm thickness. The average grain diameter of the sintered compact was 4.5 µm and the relative density was 99.9%. This sintered compact was reprocessed to 127 mm long, 381 mm wide, and 6 mm thick, and bonded to the copper baking plate, and the ITO sputtering target was produced.

The target was embedded in the sputtering apparatus and sputtered at 100 kWh, and it was confirmed that no generation of nodules to the target surface occurred. Furthermore, the resistance value of the ITO film (200 nm) formed using this sputtering target was measured, and was 0.2x10 <-3> ohm-cm. As a result, it was confirmed that the ITO film had a resistance value equivalent to that of the ITO film formed by using the ITO target sintered with only unused raw material powder.

(Comparative Example)

The ITO target after use was heated to 200 degreeC, it peeled from a baking plate, and it was immersed in 50% dilute acid for 24 hours, and the bonding solder for adhesion on the surface was removed. Each target was divided by dividing the ITO target into an appropriate size, putting 200 kg of these target pieces together with 20 liters of pure water into a 300 liter resin container, and stirring the vessel at a rotation speed of 35 rpm for 24 hours. The pieces were broken up. Thereafter, the crushed powder was classified to recover a powder having a thickness of 100 μm or less. The average particle diameter of the obtained ITO powder was 2 micrometers (maximum value 80 micrometers).

In a resin container of a capacity of 200 liters, 30 weight% (42 kg) of this ITO powder, 70 weight% of unused raw material powder (88.2 kg of indium oxide powder, 9.8 kg of tin oxide powder), and a zirconia ball of 10 mm in diameter ( 272 kg of agitating medium) 37.4 liters of pure water and 2.31 liters of carboxylic acid-based dispersant were added thereto, followed by mixing for 84 hours. The average particle diameter of the obtained slurry was 0.7 µm (maximum value of 10 µm), the concentration was 78%, and the viscosity was 200 cps. 1 weight% of carboxylic acid binders were added to the prepared slurry, and the slurry was degassed under vacuum at 20 rpm for 30 minutes.

The plaster mold of the double-sided structure which can manufacture the molded object of 415 mm in length, 780 mm in width, and 17 mm in thickness was prepared. In this gypsum mold, the slurry was poured at 3 kg / cm <^2> of shaping | molding pressure by adjusting the injection valve of a defoaming machine, and it shape | molded. Molding time was 80 minutes. The obtained molded object was naturally dried in a drying chamber at 30 ° C. for 6 days to obtain a molded product having a length of 380 mm, a width of 780 mm, and a thickness of 17 mm. Thereafter, the molded body was degreased under heating conditions at 600 ° C. for 3 hours in the air. After degreasing, the molded body was sintered. Sintering temperature was 1600 degreeC and sintering time was 8 hours. Sintering atmosphere was made into oxygen atmosphere, and oxygen introduction amount was 200 liters per minute.

The obtained sintered compact was 310 mm long, 610 mm wide, and thickness 15 mm. Both surfaces of this sintered compact were ground and the cross section was cut | disconnected, and it finished by 300 mm length, 610 mm width, and 7 mm thickness. The average grain diameter of the sintered compact was 7.0 micrometers and the relative density was 99.2%. This sintered compact was reprocessed to 127 mm long, 381 mm wide, and 6 mm thick, and bonded to the copper baking plate, and the ITO sputtering target was produced.

The target was embedded in a sputtering apparatus and sputtered at 100 kWh, with many nodules identified on the target surface. Furthermore, the resistance value of the ITO film (200 nm) formed using this sputtering target was measured, and was 0.8x10 <-3> ohm-cm. As a result, it was confirmed that the ITO film had a higher resistance value than the ITO film formed by using the ITO target sintered with only unused raw material powder.

As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to this, A various deformation | transformation is possible for it based on the technical idea of this invention.

For example, in the above embodiment, although the vibrating ball mill was used for preparation of 2nd ITO powder, you may use other grinding methods, such as a wet jet mill.

Moreover, in the above embodiment, although the sintering atmosphere of the molded object was made into the oxygen gas atmosphere, it is not limited to this, It may be called an atmospheric atmosphere.

2 sputtering target (deprecated)
2a Sintered Piece
3a, 3b resin container
4 molding
P1 First ITO Powder
P2 Secondary ITO Powder
P3 tertiary ITO powder
S slurry
Sc sintered body

Claims (11)

In the coarse grinding process of crushing a group of sintered pieces mainly composed of indium oxide and tin oxide in a container while stirring, a first ITO powder having a first average particle diameter is produced;
In a pulverizing process of grinding the first ITO powder by a medium stirring mill or a jet mill, to prepare a second ITO powder having a second average particle diameter smaller than the first average particle diameter,
In a mixed fine grinding step of mixing the indium oxide powder and the tin oxide powder with the second ITO powder and pulverizing the mixed powder, a third ITO powder having a third average particle diameter smaller than the second average particle diameter is produced. and,
By preparing a molded body by casting the slurry containing the third ITO powder in the formwork,
To sinter the molded body
Method for producing ITO sintered body. The method of claim 1,
In the step of producing the first ITO powder, the group of sintered pieces is crushed in a resin container.
Method for producing ITO sintered body. The method of claim 2,
In the step of producing the third ITO powder, the third ITO powder is produced by a medium stirring mill.
Method for producing ITO sintered body. The method of claim 3,
The said 3rd average particle diameter is 0.20 micrometer or more and 0.30 micrometer or less
Method for producing ITO sintered body. The method of claim 1,
The mixing ratio of the mixed powder in the third ITO powder is 10% by weight or more and 40% by weight or less
Method for producing ITO sintered body. The method of claim 1,
The sintered piece group is a divided piece group of the used ITO sputtering target.
Method for producing ITO sintered body. In the coarse grinding process of crushing a group of sintered pieces mainly composed of indium oxide and tin oxide in a container while stirring, a first ITO powder having a first average particle diameter is produced;
In a pulverizing process of grinding the first ITO powder by a medium stirring mill or a jet mill, to prepare a second ITO powder having a second average particle diameter smaller than the first average particle diameter,
In a mixed fine grinding step of mixing the indium oxide powder and the tin oxide powder with the second ITO powder and pulverizing the mixed powder, a third ITO powder having a third average particle diameter smaller than the second average particle diameter is produced. and,
By preparing a molded body by casting the slurry containing the third ITO powder in the formwork,
To sinter the molded body
Method for producing an ITO sputtering target. In the coarse grinding process of crushing a group of sintered pieces mainly composed of indium oxide and tin oxide in a container while stirring, a first ITO powder having a first average particle diameter is produced;
In a pulverizing process of grinding the first ITO powder by a medium stirring mill or a jet mill, to prepare a second ITO powder having a second average particle diameter smaller than the first average particle diameter,
In a mixed fine grinding step of mixing the indium oxide powder and the tin oxide powder with the second ITO powder and pulverizing the mixed powder, a third ITO powder having a third average particle diameter smaller than the second average particle diameter is produced. and,
By preparing a molded body by casting the slurry containing the third ITO powder in the formwork,
Produced by sintering the molded body
ITO sputtering target. 9. The method of claim 8,
The said 3rd average particle diameter is 0.20 micrometer or more and 0.30 micrometer or less
ITO sputtering target. 9. The method of claim 8,
The mixing ratio of the mixed powder in the third ITO powder is 10% by weight or more and 40% by weight or less
ITO sputtering target. 9. The method of claim 8,
The sintered piece group is a divided piece group of the used ITO sputtering target.
ITO sputtering target.

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