JP2007230853A - Ito powder, its production method and method for producing ito sputtering target - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably produce an ITO sputtering target having excellent characteristics free from the generation of nodules. <P>SOLUTION: By using ITO powder in which the ratio between the diameter equivalent to a specific surface area obtained by a BET method and the diameter of crystallite obtained by X-ray diffraction, (the diameter equivalent to a specific surface area/the diameter of crystallite) is <1.0, an ITO sintered compact having extremely high density can be stably produced, thus an ITO sputtering target having excellent characteristics free from the generation of nodules can be produced. The ITO powder can be obtained by pulverizing an ITO sintered compact, and the reuse of an ITO sintered compact recovered from a used target or the like is made possible. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an ITO sputtering target used for producing a transparent conductive film and a raw material powder thereof.

  ITO (Indium Tin Oxide) thin films have high conductivity and high transmittance and can be easily finely processed. Therefore, they are used for display electrodes for flat panel displays, window materials for solar cells, antistatic films, etc. . Such an ITO thin film is manufactured by a chemical film-forming method such as spray pyrolysis or CVD, and a physical film-forming method such as vapor deposition or sputtering. A sputtering method that can obtain a high-performance film is mainly used. As a sputtering target used for manufacturing an ITO thin film by a sputtering method, an alloy target (IT target) made of metal indium and metal tin, or a composite oxide target (ITO target) made of indium oxide and tin oxide is used. Compared to IT targets, ITO targets have less change over time in the resistance value and transmittance of the obtained film, and the film formation conditions can be easily controlled. Therefore, there is a method using an ITO target in forming an ITO thin film by sputtering. It has become mainstream.

However, when the ITO target is continuously sputtered in a mixed gas atmosphere of argon gas and oxygen gas, black deposits called nodules are deposited on the surface of the target as the integrated sputtering time increases. This black deposit, which is considered to be a lower oxide of indium, is deposited around the erosion part of the target, so it tends to cause abnormal discharge during sputtering, and itself is a source of foreign matter (particles). It is known that the decrease in yield due to particles has become a big problem particularly in LCDs and the like that have recently become cheaper. In order to reduce this nodule, it is effective to increase the density of the ITO target. As the high-density ITO target, a sintered body having a density of 99.5% (7.120 g / cm ³ ) or more is usually used. Yes. The ITO target is manufactured by molding and sintering a mixed powder of indium and tin oxide, which is an expensive rare metal. Due to the expensive raw materials and complicated manufacturing process of the sintered body, the target price is low. Is expensive, and there is a strong demand for a reduction in target manufacturing costs.

  Furthermore, in order to obtain a high-density ITO sintered body, it is necessary to control the powder physical properties such as specific surface area (BET value), crystallite diameter, and particle size within a certain range for the indium oxide powder as a raw material. Yes (see Patent Documents 1 to 3). For this purpose, indium hydroxide is recovered using various indium salts by methods such as neutralization precipitation, crystallization, and electrolysis, followed by drying and calcination, and a complicated manufacturing process until indium oxide is obtained. It needs to be strictly controlled, which is one factor that raises the cost of the ITO target.

  On the other hand, a method for producing an ITO sintered body from a powder obtained by pulverizing an ITO sintered body has been proposed as a simple powder manufacturing process (see, for example, Patent Documents 4 to 6).

  Patent Document 4 is a method in which particles obtained by roughly pulverizing an ITO sintered body are pulverized by a ball mill using zirconia balls as a pulverizing medium, and molded and sintered. However, this method has a problem that impurities from the zirconia balls are unavoidably mixed and difficult to use as a high-purity sputtering target, and the resulting sintered body density is low.

  Patent Document 5 proposes a method in which an ITO sintered body is recovered as a pulverized powder by a pulverization method called self-pulverization and sintered. The self-pulverization is a wet ball mill pulverization without a pulverization medium (ball) using the raw material itself, that is, in this case, an ITO sintered body as a pulverization medium. Although this method can avoid the problem of impurity contamination, the pulverized powder obtained by the self-pulverizing technique is not a powder having sufficient sinterability, so the sintered density of the obtained ITO sintered body is also a special firing called hot press. Even if the sintering method is used, the theoretical density is 97 to 98%, and the ordinary sintering in oxygen is about 78 to 90%, which is not sufficient as a raw material powder for a high-density ITO target.

  Further, in Patent Document 6, the sintering property is improved by reducing coarse powder particles by wet ball milling of an ITO sintered body using a resin-made grinding media, and 99.8% or more by firing at 1600 ° C. A sintered body is obtained. However, the powder obtained by this method has a large dependence of the sintered body density on the firing temperature, so when mass-produced, it suddenly sinters due to factors such as the temperature distribution of a large firing furnace used in mass production. The body density may be lowered, and the distribution of the density of the sintered body that directly affects the quality of the ITO target is increased, which is a serious problem in production and quality control.

Japanese Patent Laid-Open No. 05-193939 Japanese Patent Laid-Open No. 07-188912 JP-A-10-095615 Japanese Patent Application Laid-Open No. 11-1003003 JP 07-316798 A Japanese Patent Laying-Open No. 2005-075648

  An object of the present invention is to provide an inexpensive raw material powder having good sinterability for producing a high-density ITO sintered body.

  As a result of intensive studies on the raw material powder for producing a high-density ITO sintered body, the present inventors have determined the specific surface area equivalent diameter and X-ray diffraction of the ITO powder used as the raw material by the BET method. There is a close correlation between the ratio of the crystallite diameter and the density of the ITO sintered body obtained by molding and sintering the powder, in particular, the specific surface area equivalent diameter determined by the BET method and the X-ray The use of ITO powder characterized in that the ratio of the crystallite diameter determined by diffraction (specific surface area equivalent diameter / crystallite diameter) is less than 1.0 has found that low-temperature sinterability is improved. The present invention has been completed.

  That is, according to the present invention, in the production of an ITO sputtering target using a sintered body made of indium, tin and oxygen (ITO sintered body) as a target material, the specific surface area equivalent diameter and X-ray determined by the BET method of the raw material powder. The ITO powder is characterized in that the ratio of crystallite diameter obtained by diffraction (specific surface area equivalent diameter / crystallite diameter) is less than 1.0, and the powder is further molded into a predetermined shape and sintered. And a process for obtaining an ITO sintered body. Moreover, in the manufacturing method of the ITO sputtering target of this invention, it is preferable that the raw material ITO powder grind | pulverizes an ITO sintered compact and manufactures it. Furthermore, the present invention is a method for producing ITO powder, characterized in that a slurry is produced by bead mill grinding using an ITO sintered body to be ground as a grinding media, and the slurry is dried to obtain a powder.

  As shown in FIG. 1, the powder generally has crystallites aggregated to form primary particles, and the primary particles aggregated to form secondary particles. At this time, the diameter of the crystallite can be indicated by the crystallite diameter obtained by X-ray diffraction, and the diameter of the primary particle can be indicated by using a specific surface area equivalent diameter obtained by approximating the particle from the specific surface area. Therefore, the ratio between the specific surface area equivalent diameter determined by the BET method and the crystallite diameter determined by X-ray diffraction (specific surface area equivalent diameter / crystallite diameter) theoretically shows a value of 1 or more. The ITO powder in the present application is characterized in that the ratio of the specific surface area equivalent diameter to the crystallite diameter (specific surface area equivalent diameter / crystallite diameter) is less than 1.0. A more preferable range of the ratio between the specific surface area equivalent diameter and the crystallite diameter is 0.9 or less, and more preferably 0.8 or less.

  Such a special powder can be obtained, for example, by pulverizing the powder. The details are not clear, but the primary particles are crushed and further surface cracks are generated to increase the specific surface area (decrease the equivalent diameter) and at the same time give the crystallites a large strain, so that X-ray diffraction As a result, it is considered that the crystallite diameter obtained from the above is increased, and the ratio of the specific surface area equivalent diameter to the crystallite diameter is less than 1.0. By doing so, the sinterability of the ITO powder, particularly the low temperature sinterability, is improved. This is presumably because the action of reducing or eliminating the strain during sintering contributes to the improvement of the sinterability of the powder by giving large strain to the crystallites of the ITO powder as a raw material.

  The specific surface area of the present invention is measured by an ordinary BET method specific surface area measuring apparatus, and the specific surface area equivalent diameter is a value obtained by approximating particles from a BET value by sphere approximation. In addition, the size of the crystallite is based on the half-value width of the diffraction peak of the (222) plane of X-ray diffraction, and Scherrer's formula (assuming that the crystal has no imperfections and the peak spread depends only on the size of the crystallite) It is the value calculated | required using.

  As a method for producing such a special powder, a manufacturing method and conditions may be set as appropriate so as to satisfy the conditions of the present invention. For example, a method of effectively applying an external force to primary particles or crystallites may be used. Conceivable. In general, powders obtained by calcining hydroxide are strong aggregates. Therefore, even if an external force is applied to the powder, the aggregate structure of the powder absorbs the external force or the external force disintegrates the aggregate. It is difficult to give large strain to the crystallites, but if it can be pulverized effectively, the powder of the present invention can be obtained even from a calcined hydroxide powder. is there. On the other hand, when the ITO sintered body is pulverized to obtain a powder, the sintered body as a raw material has a large crystallite diameter, and thus the crystallite is easily pulverized directly in the pulverization process. Furthermore, since the powder is obtained by pulverization of the sintered body, the powder is present as crushed pieces and weakly agglomerated and is relatively monodispersed, so that the force applied for pulverization is directly applied to the primary particles. It is easy to act on crystallites. Therefore, when the sintered body is pulverized to obtain a powder, it is possible to obtain a powder having a relatively small ratio of specific surface area equivalent diameter to crystallite diameter (specific surface area equivalent diameter / crystallite diameter).

  As a method for pulverizing the ITO sintered body according to the present invention, the sintered body is preliminarily pulverized, and the obtained crushed sintered body is used as an object to be pulverized and a pulverizing medium to perform bead mill pulverization. The bead mill is an apparatus that pulverizes the powder, which is made into a slurry with a solvent such as water, with beads (pulverization media). The beads are filled in the pulverization chamber and the slurry is stirred in the beads stirred by a stirring blade or a rotary rotor. In general, the method for separating beads and slurry (slit type, centrifugal type, gap type, etc.) has been devised, and the bead diameter is about 0.05 to several mm, and the rotation speed Can be several thousand to several tens of thousands rpm, and is an apparatus with extremely high pulverization efficiency compared to a ball mill. However, wear of the grinding media is unavoidable, and there is contamination from the grinding media in proportion to the grinding force according to the grinding conditions. Can be arbitrarily set depending on the desired powder physical properties, and a powder having a ratio of a surface area equivalent diameter to a crystallite diameter (specific surface area equivalent diameter / crystallite diameter) of less than 1.0 can be easily obtained.

  The ITO sintered body of the present invention is a sintered body substantially composed of indium, tin and oxygen, and may be a sintered body containing inevitable impurities. Furthermore, the ITO sintered body of the present invention is made of magnesium (Mg), germanium (Ge), etc. added to adjust the resistivity of the formed thin film or to change other characteristics such as etching characteristics. An ITO sintered body containing an element may be used. However, when such an ITO sintered body is pulverized into a powder, it is necessary to sufficiently manage raw materials and processes so that sintered bodies having the same composition are used and sintered bodies having different compositions are not mixed. .

  Hereinafter, the present invention will be described in detail.

  The ITO sintered body used in the present invention is not particularly limited in shape, composition, relative density, etc., for example, those that have lost commercial value due to generation of cracks, cracks, etc. in the manufacturing process such as firing, or used For example, the ITO sputtering target obtained by peeling off the target material of the ITO sputtering target from the backing plate may be one obtained by removing the deposits and the bonding material.

  In the present invention, the above-mentioned ITO sintered body is coarsely pulverized in advance by a roll crusher or a jaw crusher. The particle size to be roughly pulverized may be a size that can be charged into a bead mill, and may be pulverized to a size of about 1 to 5 mm or less, depending on the apparatus structure of the bead mill. In the pulverizer used for the coarse pulverization, it is preferable that the portion in contact with the ITO sintered body is zirconia. These coarse pulverizations have a very short action time on the ITO sintered body, and even when several hundred kg of the sintered body is processed to 2 mm or less, zirconia contamination is not substantially observed.

  Next, the coarsely pulverized ITO sintered body is used as an object to be pulverized and a pulverization medium, and bead mill pulverization is performed only with water and the sintered body. The ITO sintered body is agitated by a stirring blade or a rotating rotor rotating at several thousand to several tens of thousands of rpm, and the sintered bodies collide or rub against each other, so that the sintered body is worn and pulverized powder is generated. This pulverized powder is dispersed in water to form a slurry, which is circulated through a bead mill pulverizer. In addition, since the ITO sintered body in the bead mill is worn and reduced, the coarsely ground ITO sintered body is supplied directly or indirectly into the bead mill using a feeder or the like periodically (see FIG. 2). It is preferable in terms of operation management that the ITO sintered body is supplied in an amount suitable for the pulverized sintered body by measuring the specific gravity of the slurry, etc., so that a constant sintered body always remains in the bead mill. . In this pulverization method, the shape of the ITO sintered body immediately after the introduction of the bead mill is angular, and coarse particles are generated by cracking or chipping. However, the sintered body pulverized for a certain period of time has a gentle surface like a meteorite. Is round and flat. When the sintered body becomes like this, the generation of coarse particles due to the cracks and chipping of the sintered body itself is almost eliminated, contributing to the generation of fine particles due to grinding between the sintered bodies and the pulverization of the powder in the slurry. Thus, the sintered body can be effectively pulverized. Also, when grinding first, the coarsely ground ITO sintered body that is first filled in the grinder is put in a pot and rotated, for example, to round the corners of the sintered body in advance to manage operation and gain. From the viewpoint of stability of physical properties of the obtained powder.

  The grinding conditions of the bead mill vary depending on the type (structure and method) of the apparatus, but the conditions in the case of using ordinary beads (grinding media) can also be used for direct grinding of the sintered body. Moreover, it is preferable to use what gave resin linings, such as nylon and urethane, in the inside of the grinding | pulverization chamber of a bead mill, and the part which sintered compacts, such as a stirring blade and a rotation rotor, contact directly.

  Next, the pulverized slurry obtained by bead mill pulverization is dried to obtain a pulverized powder. The drying method is not particularly limited, but it is preferable to perform the drying at as low a temperature as possible in order to suppress aggregation during drying. For example, a method in which the pulverized slurry is dehydrated in advance by a method such as centrifugal separation or a filter press, and then heated and dried at about 80 to 200 ° C. Moreover, since the powder after drying is agglomerated, it is desirable to perform the pulverization treatment with a pulverizer such as a ball mill or a hammer mill.

In the present invention, the method for forming the pulverized powder is not particularly limited, but a press molding method, a slurry molding method or the like can be applied. For example, in the case of producing a molded body by a pressing method, a predetermined mold is filled with powder, and then pressed at a pressure of 100 to 500 kg / cm ² using a powder pressing machine. If the pulverized powder has poor moldability, a binder containing an organic compound such as paraffin or polyvinyl alcohol as a main component may be added to the powder as necessary.

  In the case of producing a molded body by a casting method, a binder, a dispersant, and water are added to the pulverized powder obtained as described above, and mixed with a ball mill or the like to produce a casting molding slurry. In order to obtain a sufficient mixing effect, the mixing time is preferably 3 hours or more, more preferably 5 hours or more.

  In the case of producing a molded body by the casting method, it is not always necessary to dry the pulverized slurry obtained by pulverizing the ITO sintered body, and it is necessary to add a binder or a dispersant to the obtained pulverized slurry. A slurry for casting may be prepared by performing a treatment. At this time, the amount of ITO powder in the slurry may be calculated from the specific gravity of the slurry, and the properties of the ITO powder in the slurry may be estimated by sampling the slurry and measuring the powder contained therein. good.

  The viscosity of the slurry for casting molding is determined by the blending amount of the dispersant, binder and water described above, but preferably 100 to 5000 in order to obtain a molded article with high strength and good inking properties to the mold. A centipoise, more preferably 500 to 2500 centipoise.

  Subsequently, casting is performed using the casting slurry obtained as described above, but it is preferable to defoam the casting slurry before pouring into the mold. Defoaming may be performed, for example, by adding a polyalkylene glycol-based antifoaming agent to the slurry and performing defoaming treatment in a vacuum.

As a casting mold used for casting, a porous resin mold or a plaster mold can be used without particular limitation, and a molding pressure of 3 to 40 kg / cm ² is preferable in terms of productivity.

Subsequently, it is possible to perform a consolidation treatment by cold isostatic pressing (CIP), if necessary, on a press-molded body produced by a pressing method or a molded product after a drying treatment produced by a casting method. . At this time, the CIP pressure is preferably 1 ton / cm ² or more, and more preferably ² ton / cm ² or more in order to obtain a sufficient consolidation effect.

  Next, a dewaxing process is performed at a temperature of 300 to 500 ° C. in order to remove moisture remaining in the molded body and organic substances such as a binder. The temperature rising rate during the dewaxing treatment is preferably 5 ° C./hour or less, and more preferably 3 ° C./hour or less, in order to prevent cracking in the process of gasifying the dispersant and the binder. preferable. When the molded body is produced by a press method, the dewaxing treatment may be omitted particularly when an organic substance such as a binder is not added.

  The molded body thus obtained is sintered in a firing furnace. Any method may be used, but considering the cost of production equipment, etc., sintering in the air or in an oxygen atmosphere is desirable. In particular, in order to increase the density of an ITO sintered body, sintering in an oxygen atmosphere is preferable. It is desirable to do. However, it goes without saying that other sintering methods such as the HP method, the HIP method, and the oxygen atmosphere pressure sintering method can be used. The sintering conditions are not particularly limited, but the sintering temperature is desirably 1500 to 1650 ° C. in order to obtain a high density. The atmosphere during sintering is preferably air or a pure oxygen atmosphere. The sintering time is 5 hours or more, preferably 5 to 30 hours.

The true density of the ITO sintered body in the present invention uses a weighted average value of 7.156 g / cm ³ calculated by a mixing ratio of indium oxide and tin oxide (In ₂ O ₃ : SnO ₂ = 90: 10). It was.

  After shaping the ITO sintered body obtained as described above into a predetermined shape, surface polishing is performed as necessary, and further, for example, bonded to a backing plate made of oxygen-free copper, for example, with indium solder. An ITO sputtering target is manufactured.

  The ITO powder having a ratio of specific surface area equivalent diameter determined by the BET method to crystallite diameter determined by X-ray diffraction (specific surface area equivalent diameter / crystallite diameter) of less than 1.0 according to the present invention is low temperature sinterability. By using this, it is possible to stably produce a very high density ITO sintered body.

  Moreover, such ITO powder can be obtained by pulverizing the ITO sintered body, and the ITO sintered body recovered from defective products and used targets generated in the manufacturing process can be reused as a raw material. Is possible. In particular, it is possible to provide a high-purity and high-density ITO sintered body at low cost by producing ITO powder by bead mill grinding using an ITO sintered body to be ground as a grinding medium.

  Furthermore, by using the ITO powder of the present invention, it becomes possible to stably produce a high-density ITO sputtering target, and it is possible to provide an ITO sputtering target having excellent characteristics without generating nodules at a low cost. Become.

  The present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
The ITO sintered body that was cracked by firing and lost commercial value was coarsely pulverized to 2 mm or less by a roll crusher (roll made of zirconia), and a part was put in a resin pot to round the corners of the sintered body. Next, in the bead mill pulverization equipment configuration shown in FIG. 2, the volume corresponding to about 80% of the volume of the pulverization chamber (about 77 mmφ × 150 mmL) of the bead mill (manufactured by Shinmaru Enterprises, model DYNO-MILL) 2 kg of an ITO sintered body that had been crushed and rounded was filled, stirring was started at a rotational speed of 4500 rpm, and 1.0 kg of a sintered body that had only been roughly crushed with a feeder over 30 minutes was supplied. Furthermore, pulverization was carried out at a pulverization time of 15 minutes, with the time after the supply of the coarsely pulverized sintered body being finished as a pulverization time, to prepare a pulverized slurry.

  The obtained pulverized slurry was dehydrated by centrifugation and then placed in an oven and dried at 100 ° C. for 20 hours. The obtained dry powder was crushed by dry ball milling.

  The particle size distribution of the pulverized powder was measured by diluting an appropriate amount with pure water to which 0.25 wt% sodium hexametaphosphate was added as a dispersant, and after irradiating and dispersing ultrasonic waves for 3 minutes with a homogenizer, laser light The measurement was performed with a reflection type particle size distribution analyzer (Beckman Coulter, model LS130). The specific surface area was measured with a BET method specific surface area measuring device (manufactured by Shimadzu Corporation, model Flow Sorb II 2300), and the particle was approximated to a sphere from the BET value to obtain a specific surface area equivalent diameter (BET diameter).

  The measurement of the crystallite diameter is performed by measuring the peak of the (222) plane appearing at 2θ = about 30.5 ° with an X-ray diffractometer (manufactured by Rigaku Corporation, model RAD-C), a scan range of 29 ° ≦ 2θ ≦ 32 ° The measurement was carried out under the condition of a scan speed of 0.2 ° / min, and the half value width was used to determine it using the Scherrer equation. These values are shown in Table 1.

Next, 3 wt% of paraffin was added to this powder, and a compact was produced by pressing with a molding pressure of a surface pressure of 300 kg / cm ² using a 140 mm × 250 mm press mold.

Next, the obtained molded body was subjected to CIP treatment at a pressure of 3 ton / cm ² , degreased under the following conditions, and then subjected to two types of firing at 1550 ° C. and 1600 ° C. under the following conditions: ITO A sintered body was obtained. The obtained sintered body was subjected to density measurement by Archimedes method in accordance with JIS-R1634-1998. The measurement results of the sintered body density are shown in Table 1 for both the grinding conditions and the powder physical properties.
(Dewaxing conditions)
Dewaxing temperature: 450 ° C
Temperature increase rate: 3 ° C / hr
Retention time: 3 hr
Temperature drop rate: 10 ° C / hr
(Baking conditions)
Temperature increase rate: 50 ° C / hr
Firing temperature: 1550 ° C, 1600 ° C
Firing time: 5 hr
Temperature drop rate: 100 ° C / hr
The ITO sintered body fired at 1550 ° C. obtained as described above was processed and ground, and then bonded to a backing plate to produce a 4 ″ × 7 ″ size ITO sputtering target. As a result of discharging the produced ITO sputtering target to the life end and confirming the generation state of nodules, almost no nodules were observed.

Example 2
An ITO sintered body was produced in the same manner as in Example 1 except that the number of revolutions during bead mill grinding when producing the grinding slurry was 6000 rpm. Table 1 shows the measurement results of the physical properties and sintered body density of the powder obtained at this time.

  In addition, an ITO sputtering target was prepared in the same manner as in Example 1, and as a result of checking the state of occurrence of nodules as in Example 1, almost no nodules were observed.

Example 3
An ITO sintered body was prepared in the same manner as in Example 2 except that the pulverization time for pulverizing the bead mill was 30 minutes. Table 1 shows the measurement results of the physical properties and sintered body density of the powder obtained at this time.

  In addition, an ITO sputtering target was prepared in the same manner as in Example 1, and as a result of checking the state of occurrence of nodules as in Example 1, almost no nodules were observed.

Comparative Example 1
An ITO sintered body was produced in the same manner as in Example 1 except that the pulverized slurry was produced by ball mill pulverization under the following conditions. However, as the ITO sintered body as a raw material, a sintered body crushed to a maximum length of about 5 cm was used. Further, this ball milling does not obtain a powder corresponding to the total amount of the charged sintered body by a single grinding, but obtains a ground powder corresponding to about 5% by weight with respect to the charged sintered body. In the second and subsequent times, a sintered body and water corresponding to the amount of the obtained pulverized powder are additionally charged and pulverized.
(Crushing conditions)
Crushing container: Hard nylon 5 liter container ball: 1.5kg nylon ball with iron core
Sintered body weight: 5.7 kg
Pure water: 0.8kg
Grinding time: 24 hr
Rotation speed: 48rpm
Table 1 shows the measurement results of the physical properties and sintered body density of the powder obtained at this time.

  In addition, an ITO sputtering target was produced in the same manner as in Example 1, and as a result of confirming the generation state of nodules in the same manner as in Example 1, the generation of nodules was recognized.

Comparative Example 2
An ITO sintered body was produced in the same manner as in Comparative Example 1 except that the grinding time for ball mill grinding when producing the grinding slurry was 48 hours. Table 1 shows the measurement results of the physical properties and sintered body density of the powder obtained at this time.

  In addition, an ITO sputtering target was produced in the same manner as in Example 1, and as a result of confirming the generation state of nodules in the same manner as in Example 1, the generation of nodules was recognized.

Comparative Example 3
An ITO sintered body was produced in the same manner as in Comparative Example 1 except that the grinding time for ball mill grinding when producing the grinding slurry was 72 hours. Table 1 shows the measurement results of the physical properties and sintered body density of the powder obtained at this time.

  In addition, an ITO sputtering target was produced in the same manner as in Example 1, and as a result of confirming the generation state of nodules in the same manner as in Example 1, the generation of nodules was recognized.

  From Table 1, in Examples 1 to 3 in which the ratio between the specific surface area equivalent diameter (BET diameter) and the crystallite diameter is less than 1.0, the difference in sintered body density between 1550 ° C. and 1600 ° C. is 0. Comparative example in which the ratio of the specific surface area equivalent diameter (BET diameter) to the crystallite diameter is 1.0 or more, while the sintered body density is high even when fired at a relatively low temperature of 0.06 to 0.07%. 1-3, the difference in sintered body density between 1550 ° C. and 1600 ° C. is 0.14 to 0.29, which is more than twice that of the example, indicating that the low-temperature sinterability is inferior. FIG. 4 shows the relationship between the BET diameter and the sintered body density at 1550 ° C. in the examples and comparative examples of the present invention. From this graph, it can be seen that as the BET diameter decreases, the sintered body density increases and the sinterability improves, but the ratio between the specific surface area equivalent diameter (BET diameter) and the crystallite diameter is less than 1.0. In the example and the comparative example of 1.0 or more, the contribution of sinterability to the BET diameter is different, and even with the same BET diameter, the powder of the example has a higher sintered body density and sintering. It turns out that it is excellent in property.

It is a schematic diagram which shows the structure of a general powder particle. It is a figure which shows the structure of the bead mill grinder used in the Example of this invention. It is a figure which shows the relationship between the ratio of a specific surface equivalent diameter and a crystallite diameter (BET diameter / crystallite diameter) and a 1550 degreeC sintered compact density in the Example and comparative example of this invention. It is a figure which shows the relationship between the specific surface equivalent diameter (BET diameter) and the 1550 degreeC sintered compact density in the Example and comparative example of this invention.

Claims (7)

An ITO powder having a ratio of a specific surface area equivalent diameter determined by a BET method to a crystallite diameter determined by X-ray diffraction of less than 1.0. The method for producing an ITO powder according to claim 1, wherein the ITO sintered body is pulverized to obtain a powder. A method for producing ITO powder, comprising preparing a slurry by bead mill pulverization using an ITO sintered body to be pulverized as a pulverization medium, and drying the slurry to obtain a powder. Using an ITO sintered body obtained by molding and firing an ITO powder having a ratio of a specific surface area equivalent diameter obtained by the BET method and a crystallite diameter obtained by X-ray diffraction of less than 1.0 as a target material. A manufacturing method of an ITO sputtering target characterized. The method for producing an ITO sputtering target according to claim 4, wherein the ITO powder is obtained by pulverizing an ITO sintered body. The method for producing an ITO sputtering target according to claim 4, wherein the ITO sintered body is pulverized to obtain an ITO powder by bead mill pulverization using an ITO sintered body to be pulverized as a pulverization medium. After the ITO sintered body is pulverized by bead mill pulverization using the ITO sintered body to be crushed as a grinding medium, a slurry is obtained, and then the ITO molded body is produced using the slurry, and the molded body is fired. A method for producing an ITO sputtering target, comprising using an ITO sintered body obtained as a target material.

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