JP2016033092A - Oxide sintered compact, production method of the same, and sputtering target using the oxide sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide sintered compact which has little variation of the contraction coefficient and the density between before and after sintering, and on which defects such as a warp, a crack or the like scarcely exist, and to provide a production method thereof.SOLUTION: In a production method of an oxide sintered compact, a molded body 1 formed by pressure-molding raw material powder including a metal oxide is obtained, and a sintered compact is obtained by sintering the molded body in a state in which a shield 3 is arranged between the molded body and a heater 2 in a sintering furnace. The shield 3 is configured, excluding corners, by combining a plurality of shield pieces 4 provided with engagement parts on the ends in the length direction such that the engagement parts of the shield pieces 4 are opposing each other, and gaps 9 with widths of 1-5 mm are formed between the mutually opposing engagement parts in a shape nonlinear with respect to the thickness direction. A sputtering target is also disclosed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an oxide sintered body, a method for producing the same, and a sputtering target using the oxide sintered body as a target material.

  A transparent conductive film used for a flat panel display or the like is required to have low resistance and high transmittance. An example of the transparent conductive film that satisfies such requirements is an oxide film containing indium oxide. In particular, an indium tin oxide (ITO) film obtained by adding tin oxide to indium oxide is widely used as a transparent conductive film because of its low resistance and excellent transmittance in the visible light region. In recent years, indium oxide-based oxide films imparted with various characteristics by adding metal oxides other than indium oxide to indium oxide have been studied, and some are being put into practical use.

  Such an oxide film is often formed by a sputtering method because a large-area film can be easily obtained in production on an industrial scale. In such a sputtering method, an oxide sintered body used as a target material is manufactured by a powder sintering method, a casting method, or the like.

  Among these, the powder sintering method is a material powder made of a metal oxide having an average particle size of 0.3 μm to 2 μm, or spray-dried by adding water or an organic binder to the material powder, and several tens to several In this method, a granulated powder of 100 μm is pressure-molded by uniaxial pressing or cold isostatic pressing (CIP), and the resulting molded body is fired to obtain an oxide sintered body. However, the oxide sintered body obtained by the powder sintering method has a problem that pores are easily formed on the surface and inside, and it is difficult to increase the density. In the case where such an oxide sintered body with insufficient density is formed as a sputtering target, a high-quality transparent conductive film cannot be obtained due to the generation of nodules and arcing.

  In order to solve this problem, Japanese Patent Application Laid-Open No. 2002-47562 discloses a ratio of 0.5 L / min to 3.0 L / min of oxygen per kg of the compact in the sintering furnace when the compact is fired. Then, the organic binder contained in the molded body is volatilized while allowing oxygen to flow along at least one side of the molded body, and then the temperature is raised to 1000 ° C. over about 24 hours. 1400 ° C. to 1600 ° C.) is heated within 150 minutes and held at the sintering temperature for 10 hours or more for firing. According to such a method, the formation of vacancies is suppressed and the oxide sintered body can be made to have a high density, so that it is possible to prevent the generation of nodules and arcing during film formation. It is done.

  However, in this method, in the vicinity of the heater, the radiant heat of the heater directly hits the compact, and this part is sintered more than the other part, causing coarsening of the particles. A sintered product cannot be obtained. As a result, in the obtained oxide sintered body, variations such as shrinkage rate and density, and defects such as warpage and cracks occur.

  On the other hand, WO2010 / 125801 discloses a method of firing a molded body after storing it in a container through which oxygen can flow. Japanese Patent Application Laid-Open No. 2012-153592 discloses a method of firing a molded body after a shield made of alumina, magnesia, zirconia, or the like is installed between the molded body and a heater.

  According to these methods, it is considered that radiant heat from the heater does not directly hit the molded body, and the heat distribution in the molded body can be made uniform. However, with these methods, although a certain effect can be obtained, it is difficult to sufficiently suppress the variation in shrinkage rate and density of the oxide sintered body, and warpage and cracks resulting from these.

JP 2002-47562 A WO2010 / 125801 JP2012-153592A

  An object of the present invention is to provide an oxide sintered body and a method for producing the same, in which variations in shrinkage rate and density before and after sintering are small and defects such as warpage and cracks are hardly present.

  The method for producing an oxide sintered body of the present invention obtains a molded body obtained by pressure-molding a raw material powder containing a metal oxide, and a shielding object is disposed between the molded body and a heater in a sintering furnace. The oxide sintered body is obtained by sintering in a state where the sintered body is obtained, and the shielding object includes a plurality of shielding pieces each having an engaging portion at a longitudinal end portion, and a corner portion. Except that the engaging portions of the shielding pieces are opposed to each other, and a gap having a width of 1 mm to 5 mm is formed between the opposing engaging portions in a non-linear shape with respect to the thickness direction. It is characterized by.

  It is preferable to use an alumina shielding piece as the shielding object.

  The thickness of the shield is preferably 5 mm to 30 mm.

  The path length of the gap is preferably 1.5 to 2.0 times the thickness of the shield.

  It is preferable that the engaging portion is formed in a joint shape. In this case, it is preferable that the ratio of the length of the protruding portion of the demon engagement object to the thickness of the shielding piece is 0.5 to 1.0.

  When the area formed by the shield, the setter for placing the shield and the setter placed on top of the shield is 450 mm to 1800 mm in length and 350 mm to 1400 mm in width in plan view, the gap It is preferable to provide 3 to 6 in the vertical direction and 4 to 6 in the horizontal direction.

In the sintering step, per the volume 1L reactor, it is preferred to circulate oxygen ^{0.9 × 10 -2 L / min~3.6 ×} 10 -2 L / min.

  The oxide sintered body of the present invention is obtained by the manufacturing method described above, and the difference between the maximum value and the minimum value of the shrinkage before and after sintering is 0.3% or less, and the maximum value and the minimum value of the relative density are The difference is 0.2% or less, and the warpage amount is 0.25 mm or less.

  Further, the sputtering target of the present invention comprises a banking plate or a backing tube and a target material joined to the backing plate or the backing tube, and the oxide sintered body is used as the target material. Features.

  According to the present invention, it is possible to provide an oxide sintered body and a method for manufacturing the same, in which there is little variation in shrinkage rate and density before and after sintering, and there are almost no defects such as warpage and cracks. For this reason, the industrial significance of the present invention is extremely large.

FIG. 1 is a schematic view schematically showing a setter placed on the upper part of the shielding object in order to explain the arrangement of the compact and the shielding object in the sintering furnace. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a schematic plan view showing one embodiment of the shielding piece constituting the shielding object. FIG. 4 is an enlarged view of a portion B in FIG. Fig.5 (a)-(c) is a schematic plan view which shows another embodiment of a shielding piece. FIG. 6 is a schematic diagram illustrating the arrangement of the molded body and the shielding object in Comparative Examples 3 and 4 in a state where the setter placed on the shielding object is transmitted. FIG. 7 is an enlarged view of a portion C in FIG. FIG. 8 is a schematic diagram illustrating the arrangement of the molded body and the shielding object in Comparative Example 5 in a state where the setter placed on the shielding object is transmitted.

  In order to obtain an oxide sintered body with less shrinkage rate and density variation and less defects such as warpage and cracks, the present inventors have disclosed a container described in WO2010 / 125801 and JP2012-153592A. Or when the experiment which bakes a molded object using a shielding object was repeatedly performed, the dispersion | variation in shrinkage | contraction rate and a density, or generation | occurrence | production of a defect was not fully suppressed. In particular, when a large-sized molded body is fired or when many molded bodies are fired at the same time, variations in shrinkage rate and density increase, and accordingly, the occurrence of the above-described defects also increases.

  The present inventors have conducted research on this point, and as a result, in these conventional techniques, this cause is caused by the distribution and convection of oxygen gas within the range surrounded by the container or the shield, and further the transmission by oxygen gas. The conclusion was reached that the heat was uneven. Based on this conclusion, as a result of further research, when a compact is fired, a shield with a specific structure is placed between the heater in the sintering furnace and oxygen gas distribution, convection and The present inventors have found that heat transfer by oxygen gas can be made uniform and the above-described problems can be solved. The present invention has been completed based on this finding.

  Hereinafter, the present invention will be described in detail by dividing it into “1. Manufacturing method of oxide sintered body” and “2. Oxide sintered body and sputtering target”. Note that the present invention is not limited by the shape of the target oxide sintered body, and is applicable to the production of a cylindrical oxide sintered body as well as a flat oxide sintered body. Is also applicable.

1. Manufacturing Method of Oxide Sintered Body The manufacturing method of the oxide sintered body of the present invention is similar to the prior art,
(1) A raw material adjustment step in which a raw material powder containing a metal oxide is slurried by mixing with water or an organic binder,
(2) a granulation step in which the slurry is spray-dried to obtain a granulated powder;
(3) a pressure forming step in which a granulated powder is pressure formed to obtain a formed body; and
(4) A sintering step of firing the compact to obtain an oxide sintered body.

  In particular, the present invention is characterized in that, in the sintering step, the formed body is fired in a state where a shield having a specific structure is disposed between the formed body and a heater in the sintering furnace. Hereinafter, the present invention will be described in detail for each process.

(1) Raw material adjustment step In the raw material adjustment step, the metal oxide is mixed with water, an organic binder such as polyvinyl alcohol (PVA), an amine salt of an acrylic copolymer, and pulverized into a slurry. Necessary. Since such a slurrying means is the same as that of the prior art, description thereof is omitted here.

  In the present invention, the metal oxide is not particularly limited and can be appropriately selected according to the target oxide sintered body. For example, when obtaining oxide sintered bodies such as indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), and zinc oxide tin (ZTO), these oxide sintered bodies The oxide powder of the metal element which comprises can be used. More specifically, when trying to obtain an indium tin oxide (ITO) sintered body, as a raw material metal oxide, a mixed powder of indium oxide powder and tin oxide powder, a synthetic powder of indium oxide and tin oxide, Alternatively, a mixed powder of these can be used.

  Since indium oxide is difficult to sinter, it is often adjusted by pressure molding and sintering after adjusting the average particle size to be less than 1 μm and improving the sinterability. For this reason, indium oxide powder may aggregate in the slurry. Moreover, since indium oxide has a large specific gravity, it tends to settle in the slurry, and it may be difficult to obtain a uniform slurry. In such a case, it is preferable to promote the dispersion of the indium oxide powder by adding an appropriate amount of a dispersant to the slurry.

(2) Granulated powder step In the granulated step, the slurry obtained in the raw material adjusting step is spray-dried using a spray dryer or the like to produce a granulated powder. At this time, the drying temperature is preferably 130 to 220 ° C. If the drying temperature is less than 130 ° C., the slurry may not be sufficiently spray dried. On the other hand, when the drying temperature exceeds 220 ° C., the granulated powder becomes hard and pores are likely to be generated during pressure molding, and the resulting oxide sintered body may have a low density.

(3) Pressure molding process In the pressure molding process, the granulated powder obtained in the granulation process is filled in a mold or a rubber mold and then pressed by a uniaxial press or a cold isostatic press (CIP). Press molding. Such a molding method is the same as that of the prior art and is not particularly limited, but the molding pressure is preferably 100 MPa to 300 MPa. When the molding pressure is less than 100 MPa, the density and strength of the obtained molded product are low, and the product yield may be deteriorated. On the other hand, even if the molding pressure exceeds 300 MPa, not only a further effect cannot be obtained, but the load on the press die may increase.

(4) Sintering Step In the present invention, in the sintering step, the molded body obtained as described above is fired in a state where a shield having a specific structure is disposed between the molded body and the heater in the firing furnace. It will be necessary. In addition, the sintering furnace used for a sintering process will not be restrict | limited especially as long as the oxygen flow rate at the time of sintering can be controlled. Hereinafter, the firing process will be described with reference to FIGS.

[Configuration of sintering furnace]
A sintering furnace used in the sintering step includes heaters 2 arranged at least on both sides of the molded body 1 and preferably in a rectangular shape so as to surround four sides of the molded body 1. In this sintering furnace, a setter (ceramic shelf board) 11a for placing the molded body 1, a shield 3 arranged so as to surround the molded body 1, and a shield 3 are placed on the shield 3 and molded. A setter 11b for covering the upper portion of the body 1, and a plurality of (4 in the illustrated example) for supplying oxygen gas into the region 10 surrounded by the upper surface of the setter 11a, the lower surface of the setter 11b, and the inner wall of the shield 3. ) Oxygen gas introduction pipe 12 is installed. In addition, it is good also as a multistage structure by installing the molded object 1, the shield 3, the setter 11b, and the oxygen gas introducing pipe 12 on the setter 11b.

  The size of each component is arbitrary depending on the size of the sintering furnace and the size and number of the molded body 1 to be fired. In a generally used sintering furnace, the height of the heater 2 is about 500 mm to 2000 mm. In addition, the size of the region surrounded by the heater 2 is about 550 mm to 2200 mm in length and about 450 mm to 1800 mm in width in plan view.

  The size of the region 10 surrounded by the upper surface of the setter 11a, the lower surface of the setter 11b, and the inner wall of the shield 3 is 450 mm to 1800 mm in length and 350 mm to 350 mm in the case of producing a flat oxide sintered body. It is preferable that the height is about 1400 mm and the height is about 5 mm to 60 mm. On the other hand, when producing a cylindrical oxide sintered body, the length is 450 mm to 1800 mm, the width is 350 mm to 1400 mm, and the height is 3 mm to the total length (length in the longitudinal direction) of the cylindrical oxide sintered body. It is preferable to increase the height by about 10 mm. The height of the region 10 is the same as the height of the shield 3. The following description is basically made based on the height of the heater 2 and the size of the region surrounded by the heater 2 and the size of the region 10 shown here.

[Shield]
a) Shape As shown in FIGS. 1 to 4, the shielding object 3 is configured by combining a plurality of shielding pieces 4 or shielding pieces 8 in the width direction. More specifically, the portion other than the corner portion of the shield 3 is configured by combining the plurality of shielding pieces 4 in the width direction, and the corner portion by combining the shielding pieces 8.

The shielding piece 4 includes a main body portion 5 and engaging portions 6 formed at both ends in the width direction of the main body portion 5, and the adjacent shielding pieces 4 are combined with each other between the opposing engaging portions 6. The gap 9 having a certain width and being non-linear with respect to the thickness direction of the shield 3 is formed. In the present invention, the engaging portion 6 is defined as a structure that can engage (abut) each other when the shielding pieces 4 are moved in the thickness direction. However, in the arrangement state of the shielding object 3, a gap 9 having a non-linear path R ₁ with respect to the thickness direction is formed between both end portions in the width direction of the shielding piece 4 based on the presence of the engaging portion 6. Therefore, the end portions in the width direction of the adjacent shielding pieces 4 are not engaged with each other.

When such a shield 3 is used in combination, it is possible to prevent the radiant heat of the heater 2 arranged on both sides or four sides of the sintering furnace from directly hitting the molded body 1. Further, the gas (decomposition product gas) generated from the molded body 1 during the sintering is discharged from the region 10 to the outside through the path R ₁ formed by the gap 9. At this time, since the gas pressure and flow rate (discharge amount) are reduced and the decomposition gas discharge speed increases, the oxygen gas distribution and convection in the region 10 and heat transfer by the oxygen gas can be made uniform. . As a result, it is possible to obtain an oxide sintered body in which variations in shrinkage rate and density are suppressed and defects such as warpage and cracks are hardly present.

On the other hand, as shown in FIG. 6 and FIG. 7, when a shielding object 23 composed of a plurality of shielding pieces 24 not provided with an engaging portion is used, the radiant heat of the heater 2 is directly applied to the molded body 1. It cannot be prevented from hitting. Further, since the path R ₂ through which the decomposition product gas is discharged from the region 30 to the outside is linear, the flow rate cannot be controlled (squeezed). As a result, the resulting oxide sintered body varies in shrinkage rate and density, and defects such as warpage and cracks occur.

In the present invention, the shielding piece 8 constituting the corner portion of the shielding object 3 only needs to have the engaging portion 6 at one end. This is because, as will be described later, the molded body 1 is disposed at a constant interval from the inner wall of the shield 3, and therefore the engaging portion 6 is not formed at the other end of the shielding piece 8 constituting the corner portion. This is because the radiant heat of the heater 2 does not directly hit the molded body 1. Further, even if the path formed by the shielding pieces 8 constituting the corners is linear, if the flow rate of the decomposition product gas can be reduced by the path R ₁ of the other part, the oxygen gas in the region 10 can be reduced. This is because the distribution, convection, and heat transfer by oxygen gas can be made uniform without any trouble. However, it is also possible to form the shielding piece 8 constituting the corner portion in an L shape and form the engaging portions 6 at both ends thereof.

As shown in FIGS. 1 to 4, the shape of the engaging portion 6 of the shielding piece 4 is such that the shielding piece 4 is a continuous shape in the width direction by the engaging portions 6 at the ends of the adjacent shielding pieces 4. It is preferable to form so that it may be arrange | positioned. When the engaging portion 6 has such a shape, the path R ₁ formed by the gap 9 can be substantially S-shaped, so that the flow rate of the decomposition product gas passing through the path R ₁ can be easily and It can be controlled appropriately. As a result, it is possible to further promote the distribution and convection of oxygen gas and the uniform heat transfer by oxygen gas. Further, such a shape is not only easy to process, but also has excellent durability, and the shielding piece 4 can be used as it is even if the shielding piece 4 is reversed in the width direction. Can be made easier.

However, the shape of the engaging portion of the shielding piece is not limited to the joint shape, and as shown in FIGS. 5 (a) to 5 (c), the engagement of the adjacent shielding pieces 4a to 4c. As long as non-linear gaps 9a to 9c are formed between the portions 6a to 6c in the thickness direction, any shape of the engaging portions 6a to 6c can be adopted. In this case, the lengths (L _{a to} L _c ) of the paths R _{1a to} R _1c in the thickness direction formed by the gaps 9a to 9c are 1.5 times the thickness t of the shielding pieces 4a to 4c. What is necessary is just to regulate so that it may become -2.0 times.

b) Gap The width d of the gaps 9, 9a to 9c needs to be adjusted to 1 mm to 5 mm, preferably 1 mm to 4 mm, more preferably 1 mm to 3 mm. Thereby, during sintering, the flow rate of the decomposition product gas discharged from the region 10 to the outside can be controlled, and the oxygen gas distribution and convection in the region 10 and heat transfer by the oxygen gas can be made uniform.

  On the other hand, if the width d of the gaps 9, 9a to 9c is less than 1 mm, the decomposition product gas cannot be sufficiently discharged from the region 10. On the other hand, if the width d of the gaps 9, 9a to 9c exceeds 5 mm, the gas pressure and flow rate when the decomposition product gas is discharged from the region 10 to the outside cannot be sufficiently reduced. For this reason, in any case, the distribution and convection of the oxygen gas in the region 10 and heat transfer by the oxygen gas become non-uniform, and the shrinkage rate and density variation of the obtained sintered body cannot be suppressed.

  The number of the gaps 9, 9a to 9c depends on the size of the region 10, the size of the molded body 1, the number of molded bodies 1 to be fired simultaneously, and the like based on experiments and simulations. Distribution and convection and heat transfer by oxygen gas are determined appropriately. For example, when the size of the region 10 is in the above-described range in plan view, it is preferable to provide the gaps 9 and 9a to 9c in the vertical direction by 3 to 6 and in the horizontal direction from 4 to 6.

c) Size of shielding piece The length in the longitudinal direction of the shielding pieces 4, 4a to 4c and 8 is not particularly limited as long as the number of the gaps 9, 9a to 9c can be appropriately adjusted within the above-described range. However, it is preferably about 100 to 300 mm, more preferably about 150 to 250 mm. The lengths in the longitudinal direction of the shielding pieces 4 and 4a to 4c do not have to be all the same, and are appropriately adjusted within the above-described range so that the number and positions of the gaps 9 and 9a to 9c are optimal. May be.

  On the other hand, the height of the shielding pieces 4, 4 a to 4 c and 8 is preferably about 5 mm to 60 mm when a flat oxide sintered body is produced. In the case of producing a cylindrical oxide sintered body, it is preferably 3 mm to 10 mm higher than the entire length. In addition, since the height of the shielding pieces 4, 4 a to 4 c and 8 is the height of the region 10, it is necessary to make them all the same.

  Further, the thickness t of the shielding pieces 4, 4 a to 4 c and 8 should be appropriately selected according to the material, but is generally preferably 5 mm to 30 mm, and preferably 5 mm to 25 mm. More preferably, it is more preferably 10 mm to 20 mm. When the thickness t of the shielding pieces 4, 4 a to 4 c and 8 is less than 5 mm, not only a sufficient heat insulation effect cannot be obtained, but also the amount of heat radiated from the shielding object 3 becomes small. On the other hand, when the thickness t of the shielding pieces 4, 4 a to 4 c and 8 exceeds 30 mm, the heat insulating effect becomes excessive, and it becomes difficult to equalize the temperature in the region 10.

In addition, when the shielding piece 4 in which the shape of the engaging portion is a joint shape is used as the shielding piece, the ratio of the length w of the protruding portion 7 to the thickness t (w / t ratio) is preferably 0.5 to 1.0, more preferably 0.5 to 0.8, and still more preferably 0.5 to 0.7. If the w / t ratio is less than 0.5, the gas pressure and flow rate when the decomposition product gas is discharged from the region 10 to the outside may not be sufficiently reduced. On the other hand, when the w / t ratio exceeds 1.0, the path R ₁ becomes long, and the resistance (fluid resistance) acting on the decomposition product gas discharged from the region 10 to the outside may be excessive.

d) Material The material of the shield 3 is not particularly limited as long as it is not easily deformed or altered at the sintering temperature of the target oxide sintered body. Specifically, alumina (Al ₂ O ₃ ), magnesia (MgO), zirconia (ZrO ₂ ), alumina-silica (Al ₂ O ₃ —SiO ₂ ) -based ceramics, etc. are used as the material of the shield 3. Can do. Among these, it is preferable to use a shield made of alumina that is low in cost, has a high thermal environment, and has excellent thermal shock resistance.

[Arrangement of shielding objects]
As shown in FIGS. 1 and 2, the shield 3 is arranged between the heater 2 and the molded body 1 in the sintering furnace. More specifically, the shield 3 is disposed on the setter 11a so as to surround the plurality of molded bodies 1, and the setter 11b is disposed on the upper portion thereof. However, in the region 10 surrounded by the setters 11 a and 11 b and the shield 3, it is necessary to arrange an oxygen gas introduction pipe 12 for supplying oxygen gas. By adopting such an arrangement, it is possible to efficiently discharge the decomposition product gas from the region 10 while protecting the molded body 1 from the radiant heat of the heater 2. The distribution and convection of heat and heat transfer by oxygen gas can be made uniform.

  In addition, it is preferable that the space | interval of the inner wall of the shield 3 and the molded object 1 shall be about 20-30 mm, and the space | interval of the molded objects 1 shall be about 20-60 mm.

[Sintering conditions]
The molded body 1 is baked in a state where the shield 3 is disposed between the molded body 1 and the heater 2. The sintering conditions at this time should be appropriately selected according to the composition, shape and size of the target oxide sintered body and the number of molded bodies 1 to be fired simultaneously. For example, a plate-shaped indium oxide-based oxide sintered body having a length of 100 mm to 400 mm, a width of 50 mm to 200 mm, and a thickness of 3 mm to 10 mm, or a total length of 100 mm to 300 mm, an outer diameter of 90 mm to 180 mm, an inner diameter When an attempt is made to obtain a cylindrical indium oxide-based oxide sintered body having a thickness of 80 mm to 140 mm, the following conditions can be employed.

a) Atmosphere The atmosphere in the sintering step needs to be an oxidizing atmosphere, and 0.9 × 10 ⁻² L / min to 3.6 per 1 L of furnace volume through the oxygen gas introduction pipe 12. it is preferred to introduce the oxygen × 10 ^-2 L / min, and more preferable to introduce oxygen ^{1.5 × 10 -2 L / min~2.7 ×} 10 -2 L / min. At this time, the furnace pressure is preferably 2 atm or less in terms of gauge pressure.

If the amount of oxygen introduced is less than 0.9 × 10 ⁻² L / min per liter of furnace volume, voids may be generated inside or on the surface, and a high-density oxide sintered body may not be obtained. . On the other hand, when the amount of oxygen introduced exceeds 3.6 × 10 ⁻² L / min per liter of furnace volume, the temperature distribution in the furnace becomes non-uniform during sintering, and similarly a high-density oxide There are cases where a sintered body cannot be obtained.

b) Sintering temperature The sintering temperature needs to be within a range in which the metal oxide powder constituting the compact 1 can grow. Specifically, when an indium oxide-based oxide sintered body is to be obtained, the sintering temperature is preferably set in the range of 1100 ° C to 1600 ° C, and preferably set in the range of 1400 ° C to 1550 ° C. More preferred.

  When the sintering temperature is less than 1100 ° C., the indium oxide powder cannot be grown sufficiently. On the other hand, when the sintering temperature exceeds 1600 ° C., not only an excessive load is applied to the sintering furnace, but also the amount of volatilization of the metal components increases, resulting in problems such as composition deviation in the resulting oxide sintered body. It becomes.

c) Temperature increase rate In the present invention, the temperature increase rate in the sintering step is not particularly limited, but after volatilizing the organic binder and the like contained in the molded body 1, it takes about 24 hours to 1300 ° C. It is preferable to raise the temperature from 1300 ° C. to the sintering temperature within 150 minutes. In addition, it is more preferable that the rate of temperature increase from 1300 ° C. to the sintering temperature is as fast as possible within a range in which the temperature distribution in the furnace can be kept uniform.

2. Oxide Sintered Body and Sputtering Target (1) Oxide Sintered Body The oxide sintered body of the present invention is manufactured by the manufacturing method described above. Such oxide sintered bodies are characterized in that there is little variation in shrinkage rate and density. Specifically, the difference between the maximum value and the minimum value of the shrinkage rate before and after sintering can be 0.3% or less, preferably 0.1% or less. Further, the difference between the maximum value and the minimum value of the relative density can be 0.2% or less, preferably 0.1% or less.

  In addition, a shrinkage rate can be calculated | required by measuring the dimension of the obtained oxide sintered compact using a scale, and contrasting with the dimension of the molded object 1 measured beforehand. The relative density can be determined by the Archimedes method.

  In addition, the oxide sintered body of the present invention is characterized by almost no defects such as warpage and cracks. Specifically, the amount of warpage can be suppressed to 0.30 mm or less, preferably 0.25 mm or less.

  The amount of warpage can be obtained by placing the oxide sintered body on the surface plate, measuring the amount of lift from the surface plate at the four end portions, and calculating the average value. .

(2) Sputtering target The sputtering target of this invention is comprised from the backing plate or backing tube and the target material joined to this backing plate or backing tube similarly to the conventional sputtering target. In particular, the sputtering target of the present invention is characterized in that the oxide sintered body of the present invention is used as a target material.

  Such a sputtering target has a high density, but there is little variation in density, and there are almost no defects such as warpage and cracks, so it is possible to greatly reduce the occurrence of nodules and arcing during film formation. It is.

  Hereinafter, the present invention will be described in more detail with reference to examples. The following examples are merely illustrative, and the present invention is not limited to these implementations.

Example 1
[Raw material adjustment process-Pressure molding process]
First, 90% by mass of indium oxide powder having an average particle size of 0.4 μm and 10% by mass of tin oxide powder having an average particle size of 0.4 μm are mixed, and water and an organic binder (polyvinyl alcohol) 2% by mass. In addition, a slurry was obtained by mixing for 18 hours using a wet ball mill.

  The slurry thus obtained was spray-dried using a spray dryer (Okawara Chemical Industries, Ltd., ODL-20 type) to obtain a granulated powder having an average particle size of 60 μm.

This granulated powder is filled into a rubber mold and pressed by CIP at 3 ton / cm ² (300 MPa), and four flat molded bodies 1 having a length of 350 mm, a width of 150 mm, and a thickness of 9 mm are obtained. Produced.

[Sintering process]
In the sintering process, as shown in FIGS. 1 to 4, a shielding object 3 including a plurality of shielding pieces 4 and shielding pieces 8 was prepared. Among these, the shielding piece 4 is provided with the main body portion 5 and the engaging portions 6 constituting the joints of the joints in the state where the adjacent shielding pieces 4 are combined at both ends, and has a length in the longitudinal direction. 245 mm or 170 mm, the height is 30 mm, the thickness t is 20 mm, the length w of the protrusion 7 is 10 mm (w / t ratio = 0.5), and the thickness is 8.5 mm. It was a thing. Further, the shielding piece 8 has a length in the longitudinal direction of 235 mm or 160 mm, a height of 30 mm, a thickness t of 20 mm, and the length w of the protrusion 7 provided at the side end is 10 mm (w / t). Ratio = 0.5) and a thickness of 8.5 mm.

Next, a setter 11a (length 1000 mm, width 900 mm, thickness 30 mm) is placed in a sintering furnace having a volume of 1.1 m ³ (length 1100 mm, width 1000 mm, height 1000 mm) surrounded by the heater 2. After installing, ITO powder was spread on the upper surface with a thickness of 0.5 mm, and four molded bodies 1 were placed side by side at intervals of 50 mm. Subsequently, around the molded body 1, the shielding pieces 4 and 8 are arranged in two rows on both sides in the vertical direction and two rows on both sides in the horizontal direction and two in both sides. The shield 3 was configured. At this time, the arrangement of the shielding pieces 4 was adjusted so that a gap 9 having a width d of about 3 mm and a crank shape in the thickness direction was formed between the engaging portions 6 facing each other. The length of the path R ₁ formed by the gap 9 was 30 mm (1.5 t). Moreover, the shielding object 3 was arrange | positioned so that the space | interval of the inner wall and the molded object 1 might be about 50 mm, and the setter 11b was installed in the upper surface. In this state, the size of the region 10 surrounded by the upper surface of the setter 11a, the lower surface of the setter 11b, and the inner wall of the shield 3 was 900 mm long, 800 mm wide, and 30 mm high.

Further, as shown in FIG. 1, an oxygen gas introduction pipe 12 for introducing oxygen into the sintering furnace was installed in the region 10. Specifically, oxygen gas introduction pipes (magnetic pipes) 12 having an inner diameter of 0.5 mm were installed at intervals of 200 mm at a position 10 mm away from one end of the setter 11a (the upper end of the setter 11a in FIG. 1). Then, introduction of oxygen was started at a flow rate of 1.8 × 10 ⁻² L / min per 1 L of the in-furnace solution through these oxygen gas introduction pipes 12.

  In this state, the furnace temperature was raised from room temperature to 1300 ° C. over 24 hours. Subsequently, the temperature was raised from 1300 ° C. to 1450 ° C. over 30 minutes, and then the temperature was raised to 1500 ° C. over 10 minutes. By holding at this temperature for 15 hours, four oxide sintered bodies were produced. did.

[Evaluation of sintered oxide]
Each of the obtained four oxide sintered bodies was evaluated as follows.

a) Shrinkage rate The dimensions (length, width, and thickness) of the oxide sintered body were measured with a scale, and the shrinkage rate with respect to the molded body 1 was determined. Table 2 shows the average value of the shrinkage of the four oxide sintered bodies, the difference between the maximum and minimum values, and the standard deviation.

b) Relative density The relative density of the oxide sintered body was measured by the Archimedes method. Table 2 shows the average value of the relative density of the four oxide sintered bodies, the difference between the maximum value and the minimum value, and the standard deviation.

c) Warpage amount Place the oxide sintered body on the surface plate, measure the amount of lift from the surface plate at the four ends, and calculate the average value as the warpage amount of the oxide sintered body. did. Table 2 shows the average value of the warpage amount of the four oxide sintered bodies and the difference between the maximum value and the minimum value.

d) Defects The presence or absence of defects such as cracks was confirmed by visually observing the appearance of the oxide sintered body. The results are shown in Table 2.

(Examples 2 and 3 and Comparative Examples 1 to 5)
An oxide sintered body was obtained and evaluated in the same manner as in Example 1 except that the arrangement of the shielding object and the shape of the shielding piece constituting the shielding object were as shown in Table 1. These results are shown in Table 2.

Example 4
The granulated powder obtained in the same manner as in Example 1 was filled into a rubber mold, and formed into a cylinder having an outer diameter of 163 mm, an inner diameter of 127 mm, and a total length of 145 mm by pressing with CIP at 3 ton / cm ² (300 MPa). A shape was obtained.

  The cylindrical formed body was fired in the same manner as in Example 1 except that the shielding piece 4 having a height of 150 mm was used, and a cylindrical oxide sintered body was obtained. The cylindrical oxide sintered body was evaluated in the same manner as in Example 1 except for the measurement of the amount of warpage. The results are shown in Table 2.

[Evaluation]
From Tables 1 and 2, in the oxide sintered bodies obtained in Examples 1 to 4 belonging to the technical scope of the present invention, the difference between the maximum value and the minimum value of the shrinkage before and after sintering was 0.3%. It was confirmed that: Moreover, it was confirmed that these oxide sintered bodies had a high relative density of 99.60% or more and the difference between the maximum value and the minimum value was 0.2% or less. Furthermore, as a result of visual observation, it was confirmed that these oxide sintered bodies had almost no defects. In addition, about the flat oxide sintered compact of Examples 1-3, it was confirmed that the curvature amount is suppressed to 0.30 micrometer or less.

  On the other hand, the oxide sintered bodies obtained in Comparative Examples 1 to 5 are different from each other in the difference between the maximum value and the minimum value of the shrinkage rate, and the difference between the maximum value and the minimum value of the warpage amount and the relative density. It was confirmed that it was out of the range. The reason is considered as follows.

  In Comparative Examples 1 and 3, since there is no gap between the shielding pieces, the decomposition product gas generated from the molded body cannot be discharged to the outside from the area surrounded by the shielding object. This is thought to be due to uneven distribution, convection, and heat transfer by oxygen.

  In Comparative Example 2, since the gap between the shielding pieces was too wide, the gas pressure and the flow rate of the decomposition product gas could not be sufficiently reduced. Similarly, the oxygen distribution or convection in the region surrounded by the shielding object and This is thought to be because heat transfer by oxygen became uneven.

  In Comparative Example 4, since the engaging portion was not formed on the shielding piece, it was considered that the molded body could not be protected from the radiant heat of the heater, and the molded body was partially heated.

  In Comparative Example 5, it is considered that the gas convection becomes nonuniform due to the fact that the path formed by the gap between the shielding pieces is parallel to the shielding pieces.

  From the above, it can be seen that the manufacturing method of the present invention provides a high-quality oxide sintered body with little variation in shrinkage rate and density and almost no defects such as warpage.

DESCRIPTION OF SYMBOLS 1 Molded body 2 Heater 3 Shielding object 4, 4a-4c Shielding piece 5, 5a-5c Main body part 6, 6a-6c Engagement part 7 Protrusion part 8 Shielding piece 9, 9a-9c Gap 10 area | region 11a, 11b Setter 12 Oxygen Gas introduction pipe 23 Shielding object 24 Shielding piece 29 Gap 30 area 33 Shielding object 34 Shielding piece 39 Gap 40 area R ₁ , R _{1a to} R _1c , R ₂ path t Thickness of shielding piece w Length of protrusion d d Gap of gap width

Claims (10)

A molded body obtained by pressure-molding a raw material powder containing a metal oxide is obtained, and the molded body is sintered in a state where a shielding object is disposed between a heater in a sintering furnace to obtain a sintered body. A method for producing an oxide sintered body, comprising:
The shielding object includes a plurality of shielding pieces each having an engagement portion at a longitudinal end portion, except for a corner portion, and the engagement portions of the shielding pieces are opposed to each other and between the opposed engagement portions. , Characterized in that a gap with a width of 1 mm to 5 mm is formed in a non-linear shape with respect to the thickness direction,
Manufacturing method of oxide sinter.   The method for manufacturing an oxide sintered body according to claim 1, wherein an alumina shielding piece is used as the shielding object.   The manufacturing method of the oxide sintered compact of Claim 1 or 2 which sets thickness of the said shield to 5 mm-30 mm.   The method for producing an oxide sintered body according to any one of claims 1 to 3, wherein a path length of the gap is 1.5 to 2.0 times a thickness of the shield.   The manufacturing method of the oxide sintered compact according to any one of claims 1 to 4, wherein the engaging portion is formed in a phased joint shape.   The method for manufacturing an oxide sintered body according to claim 5, wherein a ratio of a length of the protruding portion of the engaging portion to a thickness of the shielding piece is set to 0.5 to 1.0.   When the area formed by the shield, the setter for placing the shield and the setter placed on top of the shield is 450 mm to 1800 mm in length and 350 mm to 1400 mm in width in plan view, the gap The manufacturing method of the oxide sintered compact in any one of Claims 1-6 which provides 3-6 in a vertical direction and 4-6 in a horizontal direction. In the said sintering process, 0.9 * 10 ^<-2 > L / min-3.6 * 10 ^<-2 > L / min oxygen is distribute | circulated per 1L of furnace internal volumes, The flow in any one of Claims 1-7. Manufacturing method of oxide sinter.   It is obtained by the method according to any one of claims 1 to 8, and the difference between the maximum value and the minimum value of the shrinkage ratio before and after sintering is 0.3% or less, and the difference between the maximum value and the minimum value of the relative density is An oxide sintered body having a curvature of 0.2% or less and a warpage amount of 0.25 mm or less. A sputtering target comprising a banking plate or a backing tube and a target material bonded to the backing plate or the backing tube, wherein the target material is the oxide sintered body according to claim 9.

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