JP2013256425A - Tin oxide powder for ito sputtering target, method of manufacturing mixed powder of tin oxide and indium oxide for ito sputtering target, and sintered body for ito sputtering target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an ITO sintered compact that is suitable for forming an ITO film and that excels in further high density and component uniformity; and a tin oxide powder and a mixed powder of the tin oxide powder and an indium oxide that are suitable for a raw material of the ITO sintered compact.SOLUTION: A tin oxide raw material powder is ground by a wet process bead mill until becoming such that D50 is in a range exceeding 0.4 μm and at most 1.1 μm, D90 is at most 2.5 μm, and a BET specific surface area is at least 13 m/g, and a mixed powder slurry that mixes an obtained tin oxide powder and an indium oxide powder is ground by a wet process bead mill until becoming such that D50 is in a range exceeding 0.4 μm and at most 0.5 μm, D90 is at least 1.0 μm, and a BET specific surface area is at least 12.3 m/g.

Description

  The present invention provides a tin oxide powder as one of raw materials for an ITO sputtering target, a method for producing a mixed powder of tin oxide and indium oxide for an ITO sputtering target using the tin oxide powder, and further, the mixed powder The present invention relates to an ITO sintered body obtained as a raw material and used as an ITO sputtering target by processing.

  ITO (tin-doped indium oxide) film has both high conductivity and high visible light transmission, so transparent electrodes such as solar cells, liquid crystal displays, plasma displays and touch panels, and anti-condensation heating films for window glass, Widely used in various applications that require transparent conductive films.

  Examples of methods for producing such an ITO film include sputtering, vacuum deposition, sol-gel method, cluster beam deposition, and PLD (pulse laser deposition). Among these, magnetron sputtering is used. The sputtering method including it is widely used industrially because a low-resistance film can be formed on a large-area substrate at a relatively low temperature.

  A film is formed by a sputtering method in which positive ions such as Ar ions are physically collided with a sputtering target (hereinafter referred to as “target”) installed on a cathode, and the material constituting the target is released by the collision energy. Then, a film having substantially the same composition as that of the target material is laminated on the substrate on the anode side facing each other.

  The coating method by sputtering has a feature that it can be formed from a thin film of several tens of nm to a thick film of several tens of μm at a stable film formation rate by adjusting processing time, supply power, and the like.

  When forming an ITO film, a particular problem is that abnormal protrusions called nodules are generated in the erosion portion of the ITO target or in the vicinity thereof. When this nodule is generated, the sputtering rate is lowered and abnormal discharge (micro arcing) is caused, and the productivity is remarkably lowered.

  Also, due to nodules and abnormal discharge, coarse particles (particles) float in the sputtering chamber, and they reattach to the generated thin film, resulting in thin film defects (pinholes) and protrusions. This causes a problem of deteriorating the quality of the film.

  As a measure for suppressing the generation of nodules, it is generally known to increase the density of the target and reduce the vacancies in the target. In order to improve the density of the target, it is effective to reduce the dispersion of the composition in the target by miniaturizing the indium oxide powder and tin oxide powder that are the raw material powder of the sintered body and increasing the dispersibility of each. . This is because tin oxide is insulative, so if the dispersibility of the tin oxide powder is poor, it appears as nodules on the target surface during film formation, which causes the film composition to become non-uniform.

  Further, if coarse particles are present in the raw material powder, it will cause pores in the molded body, which will remain in the sintered body, which will hinder the densification of the sintered body.

  In order to refine the tin oxide powder, the method of mechanically pulverizing the raw material powder is the simplest and the lowest cost. In particular, in order to obtain a mixed powder of tin oxide and indium oxide for obtaining a sintered body for an ITO target, it is preferable to use a media stirring type pulverizer when pulverizing each raw material powder. It is optimal to use a wet bead mill that is easy to control the agglomeration.

  If the grinding power or the number of passes is increased in this bead mill, it will be finer. However, if it is too strong, it will be difficult to control the amount of grinding. Therefore, the pulverization is required to be controlled to an appropriate strength.

  As for the indium oxide powder that is the raw material powder of the ITO target, coarse particles can be easily pulverized. However, since the tin oxide powder is hard and highly cohesive, the pulverization is more difficult than the indium oxide powder. Therefore, when pulverization is performed by simultaneously adding indium oxide and tin oxide, the pulverization conditions are set in accordance with the tin oxide so as not to leave coarse particles. For this reason, in the mixed pulverization, the indium oxide powder in the slurry is excessively pulverized, and an excessive pulverization time is required.

  From the above, it is necessary to obtain a sintered compact target having a uniform component and a high density for the formation of the ITO film. The reality is that no ITO target has been obtained.

  With respect to such problems, various improvement proposals have been proposed so far. For example, in Japanese Patent No. 4022266 and Japanese Patent Application Laid-Open No. 2009-29706, an improvement proposal for refining tin oxide powder is presented. .

  In Japanese Patent No. 40226676, the median diameter obtained from the particle size distribution (when the powder is divided into two from a certain particle diameter, the larger side and the smaller side are equal in diameter, D50) is 0.4 μm or less, And the manufacturing method of the ITO target using the tin oxide powder whose maximum particle diameter is 1.0 micrometer or less is proposed. However, since the median diameter is 0.4 μm or less and the raw material powder is too fine, the raw material powders are aggregated and sintered as a distorted aggregate. In other words, pores are formed in the ITO sintered body, which is a factor that hinders the densification of the ITO sintered body.

In JP 2009-29706 A, a tin oxide powder slurry as a raw material of an ITO target is ground using a bead mill, and the median diameter obtained from the particle size distribution exceeds 0.40 μm. The 90% particle size determined from the particle size distribution is in the range of 3.0 μm or less, preferably the median diameter determined from the particle size distribution is in the range of 0.40 μm to 0.60 μm, and , using what 90% particle size calculated from the particle size distribution is not more than the range 1.0μm, 7.12g / cm ³ (relative density 99.4% 99.5%) or more, in particular 7 It is disclosed to obtain a high-quality ITO sintered body having a high density of .130 g / cm ³ (relative density of 99.5% to 99.6%) and high quality. However, with this method, it is difficult to increase the density exceeding this verification value.

Japanese Patent No. 40226676 JP 2009-29706 A

  The present invention makes it possible to obtain an ITO sintered body excellent in further densification and component uniformity suitable for forming an ITO film, and an ITO sintered body having such excellent characteristics. An object of the present invention is to provide a tin oxide powder as a raw material and a method for producing the same.

  In order to solve the above-mentioned problems, the present inventor has intensively studied, and not only the particle diameter of the tin oxide powder as a raw material but also the BET specific surface area has an influence on the density and uniformity of the ITO sintered body. By using this tin oxide powder by strictly controlling the BET specific surface area of the tin oxide powder and the knowledge that it is a high-density ITO sintered body suitable as a sputtering target for forming an ITO film The present invention has been completed with the knowledge that can be obtained.

That is, the tin oxide powder for ITO sputtering target of the present invention has a median diameter determined from the particle size distribution in the range of more than 0.4 μm and 1.1 μm or less, and includes 90% of the whole particles determined from the particle size distribution. The diameter is 2.5 μm or less, and the BET specific surface area is 13 m ² / g or more.

In the method for producing a mixed powder of tin oxide and indium oxide for an ITO sputtering target of the present invention, the median diameter obtained from the particle size distribution of the tin oxide raw material powder using a wet bead mill exceeds 0.4 μm. Pulverizing until the particle size including 90% of the whole particle determined from the particle size distribution in the range of 1 μm or less is 2.5 μm or less and the BET specific surface area is 13 m ² / g or more; Indium oxide powder is mixed to form a slurry, and a wet bead mill is used to obtain the mixed powder slurry. The median diameter obtained from the particle size distribution of the mixed powder exceeds 0.4 μm and is 0.5 μm or less. It is characterized by pulverizing until the particle size including 90% of the whole particle determined from the distribution is 1.0 μm or less and the BET specific surface area is 12.3 m ² / g or more.

As the tin oxide raw material powder, metal tin was reacted with nitric acid to precipitate tin hydroxide, and the obtained precipitate was collected by filtration, dried, and calcined, and obtained from the particle size distribution. The median diameter is in the range of 1.5 μm to 1.8 μm, the particle size including 90% of the total particles determined from the particle size distribution is 5.0 μm or less, and the BET specific surface area is 11.0 m ² / g or more. It is preferable to use the powder which is.

Furthermore, the mixed powder of tin oxide and indium oxide for the ITO sputtering target of the present invention is obtained by the production method of the present invention, and the median diameter obtained from the particle size distribution is in the range of 0.4 μm to 0.5 μm. Yes, the particle size including 90% of the whole particle determined from the particle size distribution is 1.0 μm or less, and the BET specific surface area is 12.3 m ² / g or more.

By molding and sintering the mixed powder of tin oxide and indium oxide for ITO sputtering target of the present invention, the density calculated from the mass and volume is 7.140 g / cm ³ or more, which is a high density. A sintered body for ITO sputtering target is obtained.

  By using the tin oxide powder of the present invention, it is possible to obtain an ITO sintered body having a higher density and excellent component uniformity suitable for forming an ITO film. By using an ITO sintered body having such excellent characteristics as an ITO target, the generation of nodules due to the non-uniformity of the ITO target during the formation of the ITO film, and the sputtering rate due to the generation of the nodules It is possible to suppress the occurrence of degradation and abnormal discharge, and further the degradation of the quality of the ITO film based on these occurrences.

The tin oxide powder for ITO sputtering target of the present invention has a median diameter (D50) determined from the particle size distribution in the range of more than 0.4 μm and 1.1 μm or less, and includes 90% of the entire particles determined from the particle size distribution. The particle size (D90) is 2.5 μm or less, and the BET specific surface area is 13 m ² / g or more. Preferably, D50 is in the range of more than 0.4 μm and 0.5 μm or less, D90 is 2.4 μm or less, and the BET specific surface area is 15 m ² / g or more.

  In the production of a conventional ITO sputtering target, indium oxide powder and tin oxide powder are mixed at a predetermined ratio, and the obtained mixed powder is pulverized to a desired particle size by a wet bead mill. . However, in the state of the mixed powder slurry, since the degree of pulverization of indium oxide and tin oxide cannot be determined, tin oxide is present in a larger particle size due to relative pulverization difficulty. it is conceivable that. It is considered that this particle size difference causes pores during sintering, and hinders an increase in density of the obtained ITO sintered body. In addition, since the ITO sintered body does not have a sufficient density as described above, variations occur in the sputtering film formation using the ITO sintered body as a sputtering target, resulting in a decrease in the quality of the ITO film. It can be said that

On the other hand, in Japanese Patent Application Laid-Open No. 2009-29706, a tin oxide powder slurry is first pulverized using a bead mill alone, and then the pulverized tin oxide powder slurry is mixed with indium oxide powder. The mixed powder is further mixed and pulverized to obtain a high-quality ITO sintered body having a high density of 7.130 g / cm ³ (relative density 99.5% to 99.6%). However, when this inventor examined, the said proof value was the upper limit of the density.

The present inventor paid attention to the BET specific surface area of the tin oxide powder and intensively studied. By mixing the tin oxide powder with the indium oxide powder, the tin oxide powder has a BET specific surface area of 13 m ² / g or more. In an ITO sintered body obtained by using powder as a raw material, a high density exceeding 7.13 g / cm ³ (relative density 99.5% to 99.6%), specifically 7.140 g / cm ³ or more. It was possible to obtain knowledge that a high-quality ITO sintered body was obtained (relative density 99.7% to 99.8%). This is thought to be because the BET specific surface area of the tin oxide powder can be finely controlled while suppressing the aggregation of the raw material powders. That is, fine raw material powder improves the sinterability but tends to agglomerate and becomes pores during sintering to reduce the density of the sintered body. In the present invention, however, the BET specific surface area is strictly limited as described above. By controlling this, it is considered that the generation of aggregates can be suppressed, and as a result, pores generated due to the aggregates during sintering can be suppressed, and further improvement in density can be achieved.

The characteristics of the tin oxide powder are adjusted so that D50 is in the range of more than 0.4 μm to 0.5 μm or less, D90 is 2.4 μm or less, and the BET specific surface area is 15 m ² / g or more. By this, since aggregation of raw material powders can be suppressed, not only high density in the ITO sintered body but also higher uniformity of components can be achieved.

In addition, tin oxide powder having such characteristics can be obtained by pulverizing commercially available tin oxide powder so that D50 is in a range of more than 0.4 μm to 0.5 μm or less, At that time, in the present invention, the BET specific surface area is also strictly controlled. That is, in the present invention, as the tin oxide raw material powder before pulverization, the median diameter obtained from the particle size distribution is in the range of 1.5 μm to 1.8 μm, and the particle size includes 90% of the whole particles obtained from the particle size distribution. Is a powder having a BET specific surface area of 11.0 m ² / g or more.

  It is preferable to use a wet bead mill for the pulverization. The wet bead mill is easier to handle than the dry type and can be uniformly mixed with a dispersant, PVA (polyvinyl alcohol), etc. Furthermore, by using a spray dryer, a uniform spherical mixed raw material with good fluidity can be obtained. Can be produced. Further, by using a bead mill suitable for fine pulverization, the raw material powder can be easily adjusted to the pulverized state of the present invention. During the pulverization, the tin oxide particle size is adjusted by adjusting the number of rotations during pulverization, the number of passes, adjusting the diameter and material of beads used for pulverization, and adjusting the tin oxide powder slurry concentration. It can be performed by appropriately controlling so that the conditions can be achieved.

  In the present invention, zirconia beads are used as a carrier for a wet bead mill. As described in JP-A-2009-29706, due to the problem of zirconium contamination, it is possible to suppress the contamination problem as much as possible by using a tin oxide powder slurry having a slurry concentration of 65% or more. It is preferable because pulverization is possible and a sintered powder having excellent sinterability can be obtained.

In the present invention, the tin oxide raw material powder slurry is obtained by pulverizing using a wet bead mill, and a tin oxide powder having the above characteristics and an indium oxide powder are mixed to form a slurry, using a wet bead mill, The obtained mixed powder slurry has a median diameter determined from the particle size distribution of the mixed powder in the range of more than 0.4 μm to 0.5 μm or less, and a particle size including 90% of the total particles determined from the particle size distribution is 1.0 μm. Then, it grind | pulverizes until a BET specific surface area will be 12.3 m < ² > / g or more.

  That is, regarding the sinterability of the mixed powder of tin oxide and indium oxide as the raw material of the ITO sputtering target, the finer the particles, the better the sinterability. However, if the particles are too fine, Agglomerate and cause pores during sintering. In the present invention, by performing additional pulverization in a mixed slurry state, the properties of the obtained powder are controlled to be within the above range, and granulation is performed in a state where the particle size is uniform, thereby obtaining a high density. Raw material powder.

  The sintered body for ITO sputtering target of the present invention can be obtained by molding and sintering a mixed powder of tin oxide and indium oxide for ITO sputtering target of the present invention. Molding is performed by filling the mixed powder into a rubber mold using a cold isostatic press (CIP) machine, and press-molding the mixture at a pressure of 98 MPa to 294 MPa. Moreover, sintering is performed by baking the obtained molded object for 20 to 30 hours in 1400 degreeC-1550 degreeC in oxygen atmosphere using an electric furnace.

Example 1
A tin oxide raw material powder having a D50 of 1.8 μm, a D90 of 5.0 μm, and a BET specific surface area of 11.4 m ² / g was prepared. In addition, the particle size distribution measurement is a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, SALD-2200), and the BET specific surface area is a fully automatic specific surface area measuring device (manufactured by Mountec Co., Ltd., Maacsorb (registered trademark) HM model). -1208) was used.

  The obtained tin oxide raw material powder was mixed with pure water to produce a tin oxide powder slurry having a solid content of 65%. At this time, in order to disperse the tin oxide raw material powder in pure water, a dispersant (Sanmei Kasei Co., Ltd., Banster X754B) was added.

The prepared tin oxide powder slurry was pulverized with a bead mill so that the number of passes was 15, D50 was 0.41 μm, D90 was 2.0 μm, and the BET value was 16.0 m ² / g. Obtained. At this time, φ0.5 mm zirconia beads (YTZ) were used as the ground beads in consideration of wear resistance. The slurry containing the pulverized tin oxide powder and the indium oxide powder having a D50 of 0.43 μm, a D90 of 0.7 μm, and a BET specific surface area of 11.2 m ² / g in a solid content weight ratio. : Mixed with pure water so that indium oxide was 1: 9, a mixed slurry of tin oxide and indium oxide having a solid content of 70% was prepared.

The prepared mixed slurry of tin oxide and indium oxide was pulverized by a bead mill so that the number of passes was 5, and the mixed powder contained in this mixed slurry had a D50 of 0.41 μm and a D90 of 0.64 μm. The BET value at this time was 12.4 m ² / g.

Next, a binder (PVA) was added to the mixed slurry of tin oxide and indium oxide after pulverization, and granulation and drying were performed using a spray dryer to obtain a mixed powder of tin oxide and indium oxide. After filling this mixed powder into a silicon rubber mold having a hardness of 40 degrees, it was molded at a pressure of 294 MPa using a cold isostatic press (CIP), and the resulting molded body was sintered at 1550 ° C. Sintering was performed for 30 hours in a normal pressure oxygen atmosphere. The density of the obtained sintered body was 7.144 g / cm ^{3 as} calculated from the mass and volume.

(Example 2)
The tin oxide raw material powder obtained in the same manner as in Example 1 was used as a tin oxide powder slurry in the same manner as in Example 1, using a bead mill, the number of passes was 4, D50 was 1.06 μm, D90 was 2.33 μm, It grind | pulverized until the BET value was set to 13.5 m < ² > / g.

Next, the slurry containing the tin oxide powder and the indium oxide powder used in Example 1 were mixed with pure water in the same manner as in Example 1, and a bead mill was prepared as a mixed slurry of tin oxide and indium oxide. The number of passes was set to 5, and the mixed powder contained in this mixed slurry was pulverized so that D50 was 0.41 μm and D90 was 0.65 μm. The BET value at this time was 12.3 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.140 g / cm as calculated from mass and volume. It was ³ .

(Example 3)
The tin oxide raw material powder obtained in the same manner as in Example 1 was used as a tin oxide powder slurry in the same manner as in Example 1, using a bead mill, the number of passes was 5, D50 was 0.90 μm, D90 was 2.33 μm, Grinding was performed until the BET value was 15.5 m ² / g.

Next, the slurry containing the tin oxide powder and the indium oxide powder used in Example 1 were mixed with pure water in the same manner as in Example 1, and a bead mill was prepared as a mixed slurry of tin oxide and indium oxide. The number of passes was set to 5, and the mixed powder contained in this mixed slurry was pulverized so that D50 was 0.41 μm and D90 was 0.50 μm. The BET value at this time was 12.4 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.141 g / cm as the density calculated from the mass and volume. It was ³ .

Example 4
The tin oxide raw material powder obtained in the same manner as in Example 1 was used as a tin oxide powder slurry in the same manner as in Example 1, using a bead mill, the number of passes was 3, D50 was 1.08 μm, D90 was 2.50 μm, It grind | pulverized until the BET value was set to 13.5 m < ² > / g.

Next, the slurry containing the tin oxide powder and the indium oxide powder used in Example 1 were mixed with pure water in the same manner as in Example 1, and a bead mill was prepared as a mixed slurry of tin oxide and indium oxide. The number of passes was set to 5, and the mixed powder contained in this mixed slurry was pulverized so that D50 was 0.50 μm and D90 was 0.70 μm. The BET value at this time was 12.4 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.140 g / cm as calculated from mass and volume. It was ³ .

(Comparative Example 1)
A tin oxide raw material powder having a D50 of 1.8 μm, a D90 of 6.0 μm, and a BET specific surface area of 11.1 m ² / g was prepared.

This tin oxide raw material powder and the indium oxide powder used in Example 1 were mixed with pure water so that the weight ratio of tin oxide: indium oxide was 1: 9, and tin oxide having a solid content of 70%. And a mixed slurry of indium oxide, the number of passes was set to 5 using a bead mill, and the mixed powder of tin oxide and indium oxide was pulverized so as to be 0.41 μm as in Example 1, A slurry made of a mixed powder having a D50 of 0.40 μm and a D90 of 0.70 μm was obtained. The BET value at this time was 12.1 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.124 g / cm as a density calculated from mass and volume. It was ³ .

(Comparative Example 2)
A tin oxide raw material powder having a D50 of 2.0 μm, a D90 of 5.0 μm, and a BET specific surface area of 6.0 m ² / g was prepared.

Using this tin oxide raw material powder and the indium oxide powder used in Example 1, a mixed powder was obtained in the same manner as in Comparative Example 1. As a result, a mixed powder having a D50 of 0.40 μm and a D90 of 0.70 μm was obtained. A slurry consisting of The BET value at this time was 12.0 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.120 g / cm as a density calculated from mass and volume. It was ³ .

(Comparative Example 3)
A tin oxide raw material powder having a D50 of 1.0 μm, a D90 of 2.0 μm, and a BET specific surface area of 6.0 m ² / g was prepared.

Using this tin oxide raw material powder and the indium oxide powder used in Example 1, a mixed powder was obtained in the same manner as in Comparative Example 1. As a result, D50 was 0.42 μm and D90 was 0.70 μm. A slurry consisting of The BET value at this time was 11.8 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.127 g / cm as a density calculated from mass and volume. It was ³ .

(Comparative Example 4)
A tin oxide raw material powder having a D50 of 0.3 μm, a D90 of 1.0 μm, and a BET specific surface area of 11.0 m ² / g was prepared.

Using this tin oxide raw material powder and the indium oxide powder used in Example 1, a mixed powder was obtained in the same manner as in Comparative Example 1. As a result, D50 was 0.42 μm and D90 was 0.70 μm. A slurry consisting of The BET value at this time was 12.2 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.125 g / cm as a density calculated from mass and volume. It was ³ .

(Comparative Example 5)
A tin oxide raw material powder having a D50 of 1.8 μm, a D90 of 6.0 μm, and a BET specific surface area of 11.0 m ² / g was prepared.

Using this tin oxide raw material powder and the indium oxide powder used in Example 1, a mixed powder was obtained in the same manner as in Comparative Example 1. As a result, D50 was 0.42 μm and D90 was 1.20 μm. A slurry consisting of The BET value at this time was 12.2 m ² / g. A binder (PVA) was added to the slurry, and granulation and drying were performed in the same manner as in Example 1 using a spray dryer to obtain a mixed powder of tin oxide and indium oxide.

Further, the obtained mixed powder was molded and sintered under the same conditions as in Example 1. As a result, the density of the obtained sintered body was 7.120 g / cm as a density calculated from mass and volume. It was ³ .

  It has an excellent feature that it can obtain a sintered body excellent in densification and uniformity of components, thereby reducing abnormal projections such as quality deterioration and nodules that occur when ITO sputtering film formation is not uniform. Since it can suppress and can be used stably until the end of use, it has the outstanding effect that the tin oxide-indium oxide target for ITO film formation can be obtained at low cost.

Claims (5)

The median diameter determined from the particle size distribution is in the range of more than 0.4 μm to 1.1 μm, the particle size including 90% of the total particles determined from the particle size distribution is 2.5 μm or less, and the BET specific surface area Is a tin oxide powder for ITO sputtering target, characterized by being 13 m ² / g or more. A tin oxide raw material powder having a median diameter determined from a particle size distribution of more than 0.4 μm and 1.1 μm or less using a wet bead mill has a particle size including 90% of the total particles determined from the particle size distribution. Grinding until the BET specific surface area becomes 5 m or less and the BET specific surface area becomes 13 m ² / g or more, the obtained tin oxide powder and indium oxide powder are mixed to form a slurry, and the obtained mixed powder is obtained using a wet bead mill. The slurry has a median diameter determined from the particle size distribution of the mixed powder in the range of more than 0.4 μm to 0.5 μm or less, a particle size including 90% of the total particles determined from the particle size distribution is 1.0 μm or less, and BET A method for producing a mixed powder of tin oxide and indium oxide for an ITO sputtering target, characterized by grinding until the specific surface area becomes 12.3 m ² / g or more. As the tin oxide raw material powder, metal tin was reacted with nitric acid to precipitate tin hydroxide, and the obtained precipitate was collected by filtration, dried, and calcined, and obtained from the particle size distribution. The median diameter is in the range of 1.5 μm to 1.8 μm, the particle size including 90% of the total particles determined from the particle size distribution is 5.0 μm or less, and the BET specific surface area is 11.0 m ² / g or more. The manufacturing method of the mixed powder of the tin oxide for ITO sputtering targets and indium oxide of Claim 2 using the powder which is. A particle obtained by the production method according to claim 2 or 3, wherein the median diameter determined from the particle size distribution is in the range of more than 0.4 μm and not more than 0.5 μm, and comprising 90% of the total particles determined from the particle size distribution. A mixed powder of tin oxide and indium oxide for an ITO sputtering target, having a diameter of 1.0 μm or less and a BET specific surface area of 12.3 m ² / g or more. An ITO obtained by molding and sintering a mixed powder of tin oxide and indium oxide for an ITO sputtering target according to claim 4, and having a density calculated from mass and volume of 7.140 g / cm ³ or more. Sintered body for sputtering target.