JP2003002737A - Ito sintered compact, production method therefor and ito sputtering target using the sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ITO(indium-tin-oxide) sintered compact which is widely used as a transparent electrode of a display device represented by a liquid crystal display, a touch panel, an EL(electroluminesence) display or the like, or as the material for a transparent electrode for a solar battery, a production method therefor, and an ITO sputtering target using the sintered compact. SOLUTION: The ITO sintered compact substantially consists of indium oxide and tin oxide, where the content of tin oxide is <=35 wt.%. Its sintered density is >=7.10g/cm<3> , and the difference in the maximum density in the plane direction of the sintered compact is <=0.03g/cm<3> , and further, the average number of pores is <=800 pieces/mm<2> .

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ITO sintered body, a method for producing the same, and an ITO sputtering target using the same, and more specifically, during sputtering,
Not only can it be used as an ITO target in which the generation of nodules is suppressed and the film formation rate does not change, but it can also be used as a transparent electrode for display devices typified by liquid crystal displays, touch panels, EL displays, or transparent electrodes for solar cells. An ITO sintered body that can be widely used as a material, a method for producing the same, and I using the same
It relates to a TO sputtering target.

[0002]

2. Description of the Related Art ITO (Indium tantalum) for transparent electrodes
As a method for forming an in oxide thin film, a spray method, a vacuum deposition method, an ion plating method, a sputtering method and the like are known, but in many cases, the sputtering method is adopted. In the sputtering method, generally, under an argon gas pressure of about 10 Pa or less, a substrate is used as an anode and a target is used as a cathode, and a glow discharge is generated between them to generate argon plasma. The argon cations in this plasma are made to collide with the target of the cathode to repel particles of the target component, and these particles are deposited on the substrate to form a film.

Sputtering methods are classified according to the method of generating argon plasma. A method using high frequency plasma is called a high frequency sputtering method, and a method using direct current plasma is called a direct current sputtering method. In addition, a magnet is placed on the back side of the target to concentrate the argon plasma directly on the target to increase the collision efficiency of argon ions and to form a film even at a low gas pressure, which is called a magnetron sputtering method.

Usually, an ITO sintered body is used as a target, and a powder sintering method, that is, substantially indium oxide or tin oxide is compounded in a desired composition and pressure-molded, and then 1
It is manufactured by a method of sintering at a temperature of 400 ° C. or higher. Conventionally, an ITO sputtering target containing tin oxide (SnO ₂ ) of about 10% by weight (hereinafter, simply referred to as IT
(Sometimes called O target) has a density of 7.0 g /
It is manufactured by processing a sintered body of less than cm ^3, but recently, in order to improve the film forming performance, a higher density ITO is used.
Development of a sintered body is under consideration.

For example, in Japanese Patent Laid-Open No. 2000-144393, a density of 7.02 g / cm ³ or more (relative density of 98
% Or more) and the variation in density is about ± 1% I
A method for manufacturing a TO sintered body has been proposed. If a target is manufactured from this ITO sintered body and used for sputtering, a good film can be formed in the initial stage, but as it approaches the end stage, a black matter called nodule is generated on the target surface, causing abnormal discharge and the like, Performance (sputter rate)
Is reduced. This is because the pore distribution of the sintered body is not controlled, and when sparging for a long time,
It means that the influence cannot be ignored.

There is also known a method of uniformly controlling the surface roughness of the target. According to this method, although a stable film formation rate can be achieved with little abnormal discharge at the initial stage of sputtering, a stage from the middle stage to the latter stage can be achieved. Then, a new surface appears, nodules are generated on the target surface, abnormal discharge occurs, and it is not stable until the end. Furthermore, JP 2000
JP-A-203945 proposes a method of manufacturing an ITO target by using a firing furnace in which heating elements are provided on the side surface, the upper surface and the lower surface of a molded body. According to this method
Although there is an advantage that the molded body can be uniformly heated and the firing atmosphere can be easily controlled, the furnace lower part including the molded body setter and the furnace upper part including the auxiliary heater must be divided, resulting in a complicated apparatus. There is concern about problems such as reduced productivity.

Under these circumstances, in sputtering using a large or thick ITO target,
It has been earnestly desired to develop a high density ITO sintered body for an ITO target that suppresses the generation of nodules and does not reduce the film formation rate from the initial stage to the final stage of sputtering.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the object of the present invention is to suppress the generation of nodules during sputtering and to prevent the film formation rate from changing.
Not only can it be used as a TO target, but it can also be widely used as a transparent electrode for display devices such as liquid crystal displays, touch panels, and EL displays, or as a material for transparent electrodes for solar cells.
O sintered body and its manufacturing method, and IT using it
An object is to provide an O sputtering target.

[0009]

As a result of intensive studies to solve the above-mentioned problems, the present inventor has substantially made up of indium oxide and tin oxide and has a tin oxide content of 35% by weight or less. In the sintered body which is, if the sintered density, the maximum density difference in the plane direction of the sintered body, and the average number of holes are within a specific numerical range, nodules are less likely to occur during sputtering, and the deposition rate IT that is difficult to change
O sintered body is obtained, and further, after the raw material powder of the ITO sintered body is mixed and molded, the obtained molded body is placed on the setter of the hearth plate via spread powder, and oxygen atmosphere is set. In the method of sintering below, after providing a sufficient distance for oxygen gas to flow between the lower surface of the molded body and the hearth plate and between the upper surface of the molded body and the ceiling plate, When the oxygen atmosphere in the furnace is replaced by flowing oxygen gas over the surface of the molded body at a temperature, the ITO sintered body is held at a predetermined sintering temperature for a certain period of time and sintered. The inventors have found that the following can be obtained, and have completed the present invention.

That is, according to the first aspect of the present invention, there is provided a sintered body which is substantially composed of indium oxide and tin oxide and has a tin oxide content of 35% by weight or less. Is 7.10 g / cm ³ or more, the maximum density difference in the plane direction of the sintered body is 0.03 g / cm ³ or less, and the average number of holes is 800 holes / mm ² or less. An ITO sintered body is provided.

According to the second aspect of the present invention, the first aspect
In the invention, there is provided an ITO sintered body having a sintered density of 7.13 g / cm ³ or more.

According to the third aspect of the present invention, the first aspect
Or the invention of 2, the average number of holes is 500 / mm ²
An ITO sintered body is provided, which is characterized by:

According to a fourth aspect of the present invention, the first aspect
1 to 3, an ITO sintered body is provided, which has an average number of holes of 200 / mm ² or less.

Further, according to the fifth aspect of the present invention, the first aspect
1 to 4, an ITO sintered body is provided, which has an average pore diameter of 2 μm or less.

On the other hand, according to the sixth aspect of the present invention, the first aspect
In any one of the inventions 5 to 5, after mixing and molding a raw material powder consisting essentially of indium oxide and tin oxide,
The obtained molded body is placed on the setter of the hearth plate through the spread powder, and in a method of sintering in an oxygen atmosphere, between the lower surface of the molded body and the hearth plate, and the upper surface and the ceiling of the molded body. The oxygen atmosphere in the furnace is replaced by allowing the oxygen gas to flow through the plate and then passing the oxygen gas over the surface of the molded body at a temperature of 1000 ° C. or higher. However, there is provided a method for manufacturing an ITO sintered body, which is characterized by holding at a sintering temperature of 1400 ° C. or higher and sintering.

According to the seventh aspect of the present invention, the sixth aspect
In the invention, the flow rate of oxygen gas is 30 to 150 cm.
There is provided a method for manufacturing an ITO sintered body, characterized in that the flow rate is / min.

Further, according to the eighth aspect of the present invention, the sixth aspect
In the invention, there is provided a method for manufacturing an ITO sintered body, wherein the sintering is performed for 1 hour or more.

According to the ninth aspect of the present invention, the sixth aspect
In any one of the inventions 1 to 8 above, after sintering, before or after cooling, the sintered body is heated again to a predetermined sintering temperature and kept for 30 minutes or more in a state where the flow of oxygen gas is stopped. A method for manufacturing an ITO sintered body is provided.

On the other hand, according to the tenth invention of the present invention, an IT using the sintered body according to any one of the first to fifth inventions.
An O sputtering target is provided.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The ITO sintered body of the present invention and the method for producing the same will now be described in detail.

1. ITO Sintered Body The ITO sintered body of the present invention consists essentially of indium oxide and tin oxide, in which case the content of tin oxide component is 35% by weight or less, and The sintered density and the maximum density difference in the plane direction are 7.10 g /
It is necessary to have a specific numerical range of not less than cm ^{3 and not} more than 0.03 g / cm ³ , and the average number of holes is not more than 800 holes / mm ² . Such a sintered body is generally called a tile because it has a hard plate shape.

In the composition of the ITO sintered body of the present invention, the tin oxide content is 35% by weight or less, as described above.
When the content of tin oxide exceeds 35% by weight, the sintered density is adversely affected, and the desired ITO transparent conductive film cannot be stably obtained. In addition, components other than indium oxide and tin oxide, such as tungsten oxide, molybdenum oxide, cerium oxide, and titanium oxide, may be added to the sintered body within a range that does not impair the object of the present invention.

Further, as described above, the sintered density is 7.1.
It should be 0 g / cm ³ or more, the maximum density difference in the plane direction of the sintered body should be 0.03 g / cm ³ or less, and the average number of holes should be 800 holes / mm ² or less. The sintered density is a numerical value measured by the Archimedes method using water.

The sintered density is the minimum value measured at any place.
Is 7.10 to 7.20 g / cm^Three, Preferably 7.13
~ 7.17g / cm^ThreeIs. 7.10 g / cm^ThreeLess than
Then, uniformly form a large area ITO transparent conductive film.
Not possible, 7.20 g / cm ^ThreeDensity above is realistic
There is no. The density of the sintered body is not uniform across the plane.
The maximum density difference, that is, the maximum value of the sintered density
And the difference between the minimum value is 0.03g / cm^ThreeBelow.

The average number of holes is determined by scanning electron microscope (SE
M) is the average of the values measured on this arbitrary surface by observing the sintered body, which is 800 pieces / mm ² or less, preferably 500 pieces / mm ² or less, and more preferably 200 pieces / mm ² or less.
It is necessary to set it to mm ² or less. Average number of holes is 800 /
If it exceeds mm ² , nodules are likely to occur. Further, in order to maintain a stable deposition rate until the end of sputtering, it is desirable to reduce the variation in the average number of holes in the thickness direction. The average pore size is 5 μm
By making the thickness below preferably 2 μm or less, even if a gas component is adsorbed in the vicinity of the pores and the amount of oxygen changes, the influence can be minimized. There is a close relationship between the above-mentioned sintered density and the average number of pores, and even if either of them exceeds the above range, a high-performance ITO sputtering target cannot be obtained.

2. Method of Manufacturing ITO Sintered Body The step of manufacturing the ITO sintered body of the present invention can be roughly divided into a step of forming a compact from a raw material powder and a step of sintering the compact in a furnace. In the step of forming a compact from the raw material powders, the raw material powders consisting essentially of indium oxide and tin oxide are mixed and shaped. The subsequent sintering step is divided into a step of placing the molded body thus obtained on a hearth plate in a furnace and a setter via spread powder, and a step of sintering in an oxygen atmosphere.

The raw material powders, indium oxide and tin oxide, are mixed in a desired weight ratio, for example, 65-97: 3-35, preferably 80-95: 5-20. The average particle size of indium oxide is 0.5 μm or less, preferably 0.4 μm or less (the particle size distribution is 0.1 to 0.
8 μm particles are 85% by weight or more, more preferably 95
% Or more) is used. The tin oxide has an average particle size of 2.5 μm or less, preferably 2.0 μm.
m or less (The particle size distribution is 10 for powders with a particle size of 7.0 μm or more.
% Or less, preferably 3% by weight or less). The raw material powders can be mixed and stirred using a known device, and polyvinyl alcohol (PV
After adding A) or the like and granulating, it may be adjusted to a range of 10 to 100 μm, preferably 30 to 50 μm. The granules thus obtained are pressure-molded, for example, at 1000 kg / cm ² or more to obtain a molded body.

In the sintering step of the present invention, a space sufficient for oxygen gas to flow is previously provided between the lower surface of the molded body and the hearth plate and between the upper surface of the molded body and the ceiling plate. Then, at a temperature of 1000 ° C. or higher, while maintaining the sintering temperature of 1400 ° C. or higher while flowing the oxygen gas in the surface of the molded body to replace the oxygen atmosphere in the furnace,
Sinter. The atmosphere may be an oxygen atmosphere or an air atmosphere as long as the temperature does not reach 1000 ° C.

The internal structure of the sintering furnace used in the present invention and the manner in which the compact is installed will be described with reference to FIG. The type of furnace is not particularly limited, but an electric furnace that can easily control the heating atmosphere is usually used. A hearth plate 1 and a ceiling plate 2 are arranged on the upper and lower parts of the furnace, and a molded body 5 is mounted on the hearth plate 1 via a setter 3 and spread powder 4.

In the present invention, between the lower surface of the molded body and the hearth plate (h1) and between the upper surface of the molded body and the ceiling plate (h2).
In addition, it is important to provide a sufficient space for oxygen gas to flow. This interval depends on the size of the furnace,
It is usually 5 to 30 mm, preferably 7 to 20 mm.
The space between the lower surface of the compact and the hearth plate is adjusted by the thickness of the setter and the thickness of the spread powder. The thickness of the setter is 5 to 20
The range of mm is preferable. The width of the setter is preferably 10 to 50 mm, and the interval between adjacent setters is 30 mm or less, preferably 10 to 20 mm. The spread powder is not particularly limited, but is preferably a material that prevents the molded body from being fused to the setter and does not melt even at the sintering temperature, and an inorganic substance such as tin oxide powder is used. As the spread powder, it is preferable that the spread powder is evenly dispersed on the setter in a fine powder state, or a sheet formed into a uniform thickness is used and has a thickness of 1 to 10 mm. The above interval may be adjusted by either a setter or a spreader, but it may be easier and more reliable with a setter.

When the molded body is installed in the furnace, the total thickness of the setter and the spread powder is set to 5 to 30 mm, and the distance between the upper surface of the molded body and the upper portion of the ceiling plate is set to 5 to 30 mm. The main reason is that a sufficient flow of oxygen is taken into the molded body. If the thickness is less than 5 mm, it is difficult for oxygen gas to flow evenly on the surface of the molded product, resulting in uneven density.
Further, even if the molded body comes too close to the hearth and ceiling plate, uneven heating easily occurs at the outer peripheral portion and the central portion of the molded body. vice versa,
If it exceeds 30 mm from the surface of the molded body, the space for installing the molded body in the furnace can be wasted and a large amount of oxygen is consumed, which is not economical.

When the temperature in the furnace is raised to 1000 ° C., oxygen gas is started to flow to the upper and lower surfaces of the molded body under normal pressure to replace the oxygen atmosphere in the furnace at 1400 ° C. If more than 1 hour, the sintering temperature will be more than 1 hour,
It is preferably maintained for 5 hours or longer, more preferably 10 hours or longer. Then, the flow of oxygen gas is substantially stopped and 3
Hold at sintering temperature for 0 minutes or more, and finally cool. As described above, the sintering process of the present invention includes the preliminary sintering process, the main sintering process, and the cooling process, and if necessary, a re-sintering process may be added.

In the main sintering step, at 1400 ° C. or higher,
Oxygen gas is circulated to the upper and lower surfaces of the molded body,
Although this is a step of holding the sintering temperature for 1 hour or more, if the sintering temperature is set to 1450 to 1550 ° C., the holding time may be set to 5 to 20 hours as a guide. During the sintering process, care should be taken to keep the temperature variation within ± 10 ° C or less on the surface of the compact in order to suppress temperature variation within ± 20 ° C or less. As described above, the distance from the upper surface of the molded body to the ceiling plate and the distance from the hearth to the lower surface of the molded body are adjusted to 5 to 30 mm, preferably 7 to 20 mm, but this is also effective for stabilizing the temperature.

Oxygen gas is preferably passed at 30 to 150 cm / min. If the flow rate is too small, tin oxide is likely to evaporate from the surface of the molded body, making it difficult to increase the density and causing a composition shift. On the other hand, if the flow rate is too large, the surface of the sintered body is supercooled by the oxygen stream, resulting in uneven temperature and uneven density, and the warp amount of the sintered body increases. The distribution time may be less than 30 minutes if it is a small sintered body, but in recent years, it has become particularly large.
TO target, for example, sintered body size is 300 mm ×
About 300 mm x 6 mm, especially 400 mm x 500 mm
× 10 mm, the larger the target and the thicker it is,
Since it is difficult to control the entire temperature distribution, it is preferably 6
Hold for 0 minutes or more. As a result, the plane direction and the thickness direction are heated almost uniformly, and it is possible to greatly reduce the variations in the sintering density and the average number of pores.
The warp caused by uneven heating is also reduced by the weight of the sintered body.

After the main sintering step, the flow of oxygen gas is substantially stopped and the cooling step is started. The re-sintering step is a step of heating the sintered body to the sintering temperature again after finishing the cooling step. As in the main firing step, it may be held for 30 minutes or longer. When the sintering temperature is set to 1450 to 1550 ° C., the holding time is set to 30 minutes to 2 hours as a guide. By adding this step, the temperature in the entire furnace becomes uniform, and as a result, the heat uniformity of the sintered body is improved, and the average grain size of the crystal, the average pore diameter of the sintered body, and the average number of pores are increased. It can be controlled within a certain range.
The re-sintering step may be performed after the cooling step.

3. ITO Sputtering Target The ITO sintered body manufactured by the above method is processed into a predetermined size by surface grinding or the like, and then attached to a backing plate to obtain the ITO sputtering target of the present invention. If necessary, several tiles may be arranged in a divided shape.

This ITO sputtering target is
7.10 g / cm ³ or more in the tile (about 99 in relative density)
%) And the average number of holes inside the sintered body is 80
Since the number is controlled to 0 / mm ² or less, nodules can be effectively suppressed. That is, by adopting a sintered body having a high sintering density and a small average number of holes, even if the sputtering progresses and reaches a certain erosion depth, the number of abnormal discharges does not sharply increase, and thus a film is formed. At this time, it is not necessary to increase the power or clean the surface of the target. It is said that the number of vacancies in the sintered body is more likely to increase in the inside than in the surface portion. However, in order to stably sputter even when the erosion is near the deepest thickness, the density is particularly 7.10 g. / Cm ³ or more, and the average number of holes near the central portion in the thickness direction may be 500 / mm ² or less.

[0038]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

(Example 1) 90% by weight of indium oxide powder and 10% by weight of tin oxide powder were mixed, and 1% by weight of PVA as a binder for molding was added thereto and granulated. The average particle size of the indium oxide powder is 0.35 μm (the particle size distribution is 0.2% below 0.1 μm, 4.5% above 0.8 μm, that is, 0.1 to 0.8 μm is 95%). ．
3%), and the average particle size of the tin oxide powder is 1.
The particle size was 9 μm (the particle size distribution was 7.0 μm or more occupying 2.2%). After granulation, using granules adjusted to 30 to 50 μm, at a pressure of 2000 kg / cm ^{2 at} room temperature,
It was molded into 400 mm × 500 mm × 10 mm. The molded body is placed on the setter of the hearth plate through the spread powder of tin oxide that has been calcined, and the height from the hearth plate to the lower surface of the molded body is 7 m.
Adjusted to m, the distance from the top of the molded body to the ceiling plate is 7 mm
And When the temperature is raised to 1000 ° C., oxygen gas is flown over the surface of the molded body at a flow rate of 120 cm / min,
It hold | maintained at 1500 degreeC for 10 hours, and sintered. The oxygen flow rate was adjusted when the molded body was installed, and the oxygen flow rate was kept constant. After that, the flow of oxygen gas was stopped for 1 hour, and the mixture was naturally cooled. When the temperature was measured while oxygen gas was flowing, the temperature fluctuated ± 4 ° C near the surface of the molded body. Further, when the flow of oxygen gas was stopped, the final temperature variation was within ± 1.5 ° C. The amount of warp of the tile was measured and found to be 0.3 mm. The density calculated from the size and weight of the entire tile is 7.13 g / cm ³ , and when the density of the test piece cut into about 30 mm square is measured by the Archimedes method using water, the average is 7.153 g / cm ^3.
cm ³ , minimum 7.145 g / cm ³ , maximum 7.162 g
It was / cm ^3. Further, a portion having a density of 7.15 g / cm ³ was mirror-polished in the thickness direction and then etched, and the structure was observed by SEM. The average number of holes in the vicinity of the tile surface is 63 / mm ² , and the average number of holes in the vicinity of the center is 97.
The number of pieces / mm ² . Also, the average particle size is about 3.8 μm,
The average pore diameter was 1.5 μm. These results are shown in Table 1.
It was shown to.

(Examples 2-8) In the same manner as in Example 1,
An ITO sintered body was manufactured by changing the distance from the hearth to the lower surface of the molded body, the flow rate of oxygen, or the holding time without changing the distance from the upper surface of the molded body to the ceiling plate. The obtained sintered body was cut into a size of about 30 mm square, and the sintered density of each test piece was measured. After the tile was mirror-polished and further subjected to etching treatment, the structure was observed by SEM to measure the number of holes, and the average number of holes was determined.
The results are shown in Table 1.

Comparative Examples 1 and 2 In the same manner as in Example 1,
The ITO sintered body was manufactured by changing the distance from the hearth to the lower surface of the molded body, changing the flow rate of oxygen, and the holding time without changing the distance from the upper surface of the molded body to the ceiling plate. The obtained sintered body was cut into a size of about 30 mm square, and the sintered density of each test piece was measured. After the tile was mirror-polished and further subjected to etching treatment, the structure was observed by SEM to measure the number of holes, and the average number of holes was determined. Moreover, the average particle diameter and the average pore diameter were measured. The results are also shown in Table 1.

[0042]

[Table 1]

(Example 9) The composition of the raw material powder shown in Example 1 was changed to 80% by weight of indium oxide powder and 20% by weight of tin oxide powder, and the same granulation was carried out. The indium oxide powder has an average particle size of 0.35 μm (particle size distribution is 0.1
0.3% is less than μm, 4.6 is more than 0.8 μm.
%, That is, 0.1 to 0.8 μm accounts for 95.1%), and the tin oxide powder has an average particle size of 1.9 μm (particle size distribution of 7.0 μm or more accounts for 2.2%). Powder was used. After granulation, in the same manner as in Example 1, 400 mm x 50
After being molded into 0 mm × 10 mm and sintered, the amount of warpage of the obtained tile was 0.2 mm. Density of the whole tile, average 7.175g / cm ^3, the minimum 7.165g / ^cm 3,
The maximum was 7.187 g / cm ³ . Also, the density is 7.1
At the location of 7 g / cm ^3, the pore distribution in the thickness direction is S
It was observed by EM. The number of holes near the surface is 110 / mm ² on average, and 120 / m on average near the center in the thickness direction.
It was m ² . The average particle diameter was 2.7 μm and the average pore diameter was 1.4 μm.

(Example 10) The composition of the raw material powder shown in Example 1 was changed to 95% by weight of indium oxide powder and 5% by weight of tin oxide powder, and the same granulation was performed. The indium oxide powder has an average particle size of 0.34 μm (particle size distribution of 0.1
0.3% is less than μm, 4.2 is more than 0.8 μm
%, That is, 0.1-0.8 μm accounts for 95.5%), and the tin oxide powder has an average particle size of 1.9 μm (particle size distribution of 7.0% or more accounts for 2.2%). Powder was used. After granulation, in the same manner as in Example 1, 400 mm x 50
After being molded into 0 mm × 10 mm and sintered, the amount of warpage of the obtained tile was 0.3 mm. Density of the whole tile, average 7.14 g / cm ^3, the minimum 7.131g / cm ^3, and a maximum 7.147g / cm ^3. Also, the density is 7.13
At the g / cm ³ point, the hole direction distribution in the thickness direction is SE
When observed with M, the average number of holes near the surface is 53 /
mm ² , average 390 pieces / mm near the center in the thickness direction
It was ² . The average particle size of the sintered body was 7.8 μm, and the average pore size was 2.1 μm.

(Example 11) The composition of the raw material powder shown in Example 1 was changed to 69% by weight of indium oxide powder and 31% by weight of tin oxide powder, and the same granulation was performed. The indium oxide powder has an average particle size of 0.34 μm (particle size distribution of 0.
0.3% is less than 1 μm, and 4 is more than 0.8 μm.
2%, that is, 0.1-0.8 μm accounts for 95.5%), and tin oxide powder has an average particle size of 1.9 μm (particle size distribution of 7.0 μm or more accounts for 2.2%). Was used. After granulation, in the same manner as in Example 1, 400 mm x 50
After being molded into 0 mm × 10 mm and sintered, the amount of warpage of the obtained tile was 0.3 mm. Density of the whole tile, average 7.17 g / cm ^3, the minimum 7.162g / cm ^3, and a maximum 7.183g / cm ^3. Also, the density is 7.17.
At the g / cm ³ point, the hole direction distribution in the thickness direction is SE
When observed with M, the number of holes near the surface is 160 / mm ² on average, and 190 / m on average near the center in the thickness direction.
It was m ² . The average particle diameter was 2.1 μm and the average pore diameter was 1.2 μm.

(Example 12) The composition of the raw material powder shown in Example 1 was replaced with 97% by weight of indium oxide powder and 3% by weight of tin oxide powder, and the same granulation was carried out. The indium oxide powder has an average particle size of 0.34 μm (particle size distribution of 0.1
0.3% is less than μm, 4.2 is more than 0.8 μm
%, That is, 0.1-0.8 μm accounts for 95.5%), and the tin oxide powder has an average particle size of 1.9 μm (particle size distribution of 7.0% or more accounts for 2.2%). Powder was used. After granulation, in the same manner as in Example 1, 400 mm x 50
After being molded into 0 mm × 10 mm and sintered, the amount of warpage of the obtained tile was 0.2 mm. Density of the whole tile, average 7.11 g / cm ^3, the minimum 7.104g / cm ^3, and a maximum 7.114g / cm ^3. Also, the density is 7.11
At the g / cm ³ point, the hole direction distribution in the thickness direction is SE
When observed under M, the number of holes near the surface is 290 / mm ² on average, and 160 / m on average near the center in the thickness direction.
It was m ² . The average particle size of the sintered body was 8.1 μm and the average pore size was 2.0 μm.

(Example 13) The ITO sintered body (tile) obtained in Example 1 was bonded to a backing plate to form ITO.
A sputtering target was manufactured. This was installed in a sputtering device, and DC sputtering of 400 kWh was applied at a power of 2.5 W / cm ² and an integrated power to perform sputtering. Almost no abnormal discharge occurs from the start of film formation to about 200 kWh, and when it exceeds 200 kWh,
The number of abnormal discharges increased slightly. Further, after sputtering, there were almost no nodules in the surface erosion part, and slight nodules were observed near the periphery of the erosion part.

(Comparative Example 3) The ITO sintered body (tile) obtained in Comparative Example 1 was bonded to a backing plate to manufacture an ITO sputtering target. Example 11
Installed in the same sputtering equipment as above, 2.5 W / cm ²
DC sputtering of 400 kWh was applied with the power of 1. Even before it reached 200 kWh
Abnormal discharge gradually occurred, and when it exceeded 200 kWh, the number of abnormal discharges increased. Further, after sputtering, nodules were noticeable near the surface erosion part and the periphery of the erosion part.

[0049]

According to the present invention, in a sintered body which is substantially composed of indium oxide and tin oxide and has a tin oxide content of 35% by weight or less, the sintered density thereof is increased more than ever before and the plane direction Since the maximum density difference in 1 is reduced and the average number of holes is reduced, it is possible to provide an ITO sputtering target in which nodules are less likely to occur during sputtering and the deposition rate does not decrease. Since the ITO sputtering target with good performance can be stably supplied in this way, its industrial value is extremely large.

[0050]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a sintering furnace used in the present invention, showing a state in which a molded body is placed on a setter via spread powder.

[0051]

[Explanation of symbols]

1 hearth 2 ceiling board 3 setters 4 bedding 5 molded body h1 (distance between hearth and molded body) h2 (Ceiling-molded body distance)

Claims (10)

[Claims] 1. A sintered body consisting essentially of indium oxide and tin oxide and having a tin oxide content of 35% by weight or less, and a sintering density of 7.10 g / cm ³ or more, and The maximum density difference in the plane direction of the sintered body is 0.
It is 03 g / cm ³ or less, and the average number of pores is 800 holes / mm ² or less. 2. The ITO sintered body according to claim 1, which has a sintered density of 7.13 g / cm ³ or more. 3. The ITO sintered body according to claim 1 or 2, wherein the average number of holes is 500 / mm ² or less. 4. The I according to claim 1, wherein the average number of holes is 200 / mm ² or less.
TO sintered body. 5. The ITO sintered body according to claim 1, wherein the average pore diameter is 2 μm or less. 6. A raw material powder consisting essentially of indium oxide and tin oxide is mixed and molded, and then the obtained molded body is placed on a setter of a hearth plate via spread powder and baked in an oxygen atmosphere. In the method of binding, a temperature of 1000 ° C. or higher is provided between the lower surface of the molded body and the hearth plate and between the upper surface of the molded body and the ceiling plate with a sufficient distance for oxygen gas to flow. At 1400 ° C., while substituting the oxygen atmosphere in the furnace by circulating oxygen gas on the surface of the molded body,
The method for producing an ITO sintered body according to any one of claims 1 to 5, wherein the sintering is performed while maintaining the above sintering temperature. 7. The flow rate of oxygen gas is 30 to 150 cm /
IT according to claim 6, characterized in that it has a flow rate of a minute.
O Sintered body manufacturing method. 8. The method for producing an ITO sintered body according to claim 6, wherein the sintering is performed for 1 hour or more. 9. After sintering, before or after cooling,
The ITO sintered body according to any one of claims 6 to 8, wherein the sintered body is heated again to a predetermined sintering temperature and held for 30 minutes or more in a state where the flow of oxygen gas is stopped. Production method. 10. An ITO sputtering target using the sintered body according to claim 1.