Sintered body, sputtering target, and method for producing sintered body

Abstract

The present invention addresses the problem of providing: an IZO sintered body containing indium, zinc and oxygen, and having a small crystal grain size and high density; and a method for producing the same. The sintered body contains indium, zinc, and oxygen, and has an average crystal grain size of 2 μm or less and a relative density of 99% or more.

Description

Sintered body, sputtering target, and method for producing sintered body

[0001] The present disclosure relates to a sintered body, a sputtering target, and a method for producing a sintered body.

[0002] Thin films of oxides primarily composed of indium oxide, such as indium oxide-tin oxide (abbreviated as "ITO") and indium oxide-zinc oxide liquid oxide (abbreviated as "IZO"), have high conductivity and transparency in the visible light region, and are therefore used as electrode materials for various flat panel displays. In particular, IZO has properties such as low resistance and high transmittance when formed at room temperature, the formation of a stable amorphous film, good etching properties, and high film flatness. In addition, IZO has properties as an oxide semiconductor, and its use as a channel layer for TFTs, etc., is also being considered.

[0003] A sputtering method using a sputtering target manufactured from an IZO sintered body is widely used as a method for forming an IZO film. There have been several reports on IZO sintered bodies. Patent Document 1 discloses a technique for lowering bulk resistance by adding a small amount of tin to IZO. This technique uses tin as a dopant, and it has been shown that the bulk resistance decreases with the concentration of tin added, but no particular attention is paid to the density of the sintered body.

[0004] In addition, Patent Document 2 discloses In ２ O ３ A technique has been shown in which a mixed powder of ZnO and ZnO is pre-fired under appropriate conditions to suppress rapid progression of the phase change and improve the properties of the sintered body, such as increasing density.

[0005] Furthermore, Patent Document 3 discloses a technology in which sintered IZO is subjected to HIP (Hot Isostatic Pressing) treatment, which causes gas generated in pores in the IZO sintered body to escape along grain boundaries, thereby obtaining a dense sintered body with few pores.

[0006] Patent No. 3721080 Patent No. 6078189 Patent No. 6523510

[0007] In order to achieve high density by atmospheric sintering in an IZO sintered body containing indium, zinc, and oxygen, sintering conditions of 1400°C or higher and approximately 10 hours are required. However, high temperatures and long sintering times cause the crystal grains to become coarse, resulting in a decrease in the strength of the sintered body. In view of the above problem, the present disclosure aims to provide an IZO sintered body containing indium, zinc, and oxygen, which has small crystal grain size and high density, a sputtering target, and a method for manufacturing the sintered body.

[0008] In order to solve the above problems, the present inventors have conducted extensive research and have found that by devising a method for producing a sintered body containing indium, zinc, and oxygen, a sintered body having a small crystal grain size and high density can be obtained.

[0009] That is, the gist of the present disclosure is as follows. [1] A sintered body containing indium, zinc, and oxygen, having an average crystal grain size of 2 μm or less and a relative density of 99% or more. [2] The sintered body according to [1], having a pore area ratio of 0.25% or less. [3] The sintered body according to [1] or [2], having a Vickers hardness of 500 HV or more. [4] The sintered body according to any one of [1] to [3], having a volume resistivity of 5 mΩ cm or less. [5] A saturation C ＊ [6] The sintered body according to any one of [1] to [5], having a Zn content of 1 mass % or more and 37 mass % or less in terms of ZnO. [7] A sputtering target comprising the sintered body according to any one of [1] to [6]. [8] A sputtering target having an area of ​​44 cm ２ The sputtering target according to the above [7]. [9] In ２ O ３

[10] A method for producing a sintered body, comprising: mixing a ZnO powder with a ZnO powder, filling the resulting mixed powder into a sintering apparatus, placing a metal member constituting a metal oxide having a higher standard Gibbs energy of formation than the mixed powder around the mixed powder in the sintering apparatus, and hot pressing the mixed powder. ２The method for producing a sintered body according to [9], wherein hot pressing is carried out under the above conditions.

[0010] According to the present disclosure, it is possible to provide a sintered body and a sputtering target that contain indium, zinc, and oxygen, have a small average crystal grain size, and high density.

[0011] 1 shows a structural photograph of a sintered body (image taken by SEM) and an image analysis diagram (for reference). 2 shows images (for reference) before and after the binarization process used to determine the pore area ratio.

[0012] Below, the present disclosure will be described with reference to specific embodiments, but each configuration and their combinations in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of configurations are possible as appropriate within the scope that does not deviate from the gist of the present disclosure.

[0013] A sintered body according to an embodiment of the present disclosure (hereinafter referred to as the present embodiment) contains indium, zinc, and oxygen. A sintered body having such a composition may be referred to as an IZO sintered body. IZO is an abbreviation derived from the initials of the constituent elements indium (In), zinc (Zn), and oxygen (O). IZO thin films are used as transparent conductive films and oxide semiconductors, and are particularly used as electrode materials in displays.

[0014] An IZO thin film can usually be formed by sputtering. A sputtering target made of an IZO sintered body (sometimes referred to as an IZO sputtering target) is placed in a vacuum chamber, and argon ions generated by glow discharge are made to collide with the sputtering target at high speed, causing the ejected atoms to be deposited on an opposing glass substrate or the like, thereby forming a thin film having substantially the same composition as the sputtering target.

[0015] The sintered body according to the embodiment of the present disclosure has an average crystal grain size of 2 μm or less. By refining the crystal grains, the hardness of the sintered body can be improved. Furthermore, it is possible to suppress particle generation during sputtering. The average crystal grain size is preferably 1.5 μm or less, more preferably 1 μm or less. On the other hand, the average crystal grain size is preferably 0.2 μm or more.

[0016] The sintered body according to this embodiment has a relative density of 99% or more. The higher the relative density of a sputtering target made of an IZO sintered body, the more improved the hardness of the sintered body can be. Furthermore, particle generation during sputtering can be suppressed. Because a fine crystal structure is required for an IZO sintered body, sintering at a low temperature, which can suppress grain growth, is preferable. However, it is difficult to obtain a high-density sintered body with low-temperature sintering. However, according to the manufacturing method of the present disclosure, which will be described in detail later, it is possible to obtain a high-density sintered body while suppressing grain growth. The preferred relative density is 99.5% or more, and more preferably 99.9% or more.

[0017] In the sintered body according to this embodiment, the pore area ratio is preferably 0.25% or less. If pores are present in the sputtering target, particles will be generated from the pores during sputtering, so it is preferable to reduce the number of pores as much as possible. The pore area ratio is more preferably 0.20% or less. The pore area ratio is calculated using the following formula: Pore area ratio = (area of ​​regions corresponding to pores) / (area of ​​observed sintered body structure) x 100

[0018] The sintered body according to this embodiment preferably has a Vickers hardness of 500 HV or more. According to the present disclosure, grain growth can be suppressed, so it is possible to suppress a decrease in Vickers hardness. More preferably, it is 550 HV or more. Even more preferably, it is 600 HV or more. Particularly preferably, it is 650 HV or more. Increasing the Vickers hardness of the sintered body is particularly effective because it can suppress the occurrence of cracks during high-power sputtering. Note that the Vickers hardness is affected by the Zn content (ZnO equivalent) in the sintered body; the higher the Zn content (ZnO equivalent), the lower the Vickers hardness.

[0019] The sintered body according to this embodiment preferably has a volume resistivity of 5 mΩ·cm or less. If the volume resistivity is high, arcing occurs during sputtering, which can cause particles, so it is preferable that the resistivity be as low as possible. If oxygen deficiency occurs in the sintered body, the volume resistivity decreases, so the sintering conditions are adjusted to generate oxygen deficiency. The volume resistivity is preferably 2 mΩ·cm or less, and more preferably 1 mΩ·cm or less.

[0020] When sintered in air, no oxygen deficiency occurs in the sintered body, and the volume resistivity hardly decreases. On the other hand, when sintered under conditions of low oxygen partial pressure, such as in a vacuum or Ar atmosphere, oxygen deficiency occurs in the sintered body, the volume resistivity decreases, and the color of the sintered body also changes. Therefore, the sintered body can also be characterized by its color. L is used as an index to quantify the color of an object. ＊ a ＊ b ＊ There is a color space. ＊ represents the lightness, and L ＊ The closer to 100, the brighter it becomes (total reflection), and L ＊ The closer to 0, the darker (less reflective) the sintered body becomes. ＊ It is possible to identify it by L ＊ The value of a varies greatly depending on the surface condition (surface roughness, etc.), so it is not possible to accurately identify the color. ＊ represents the intensity of color from green to red, and b ＊ represents the intensity of the color from blue to yellow, and saturation C ＊ (C ＊ ) = {(a ＊ ) ２ +(b ＊ ) ２} １／２ Chroma C ＊ Is L ＊ Unlike the above, the intensity of the color can be grasped without being affected by the surface condition (reflection). ＊ From the viewpoint of sputtering characteristics, it is preferable to specify the color by the chroma C ＊is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less.

[0021] The sintered body according to this embodiment contains indium (In), zinc (Zn), and oxygen (O), and the content of each element is not particularly limited. However, since the Zn content affects the conductivity of the target film, it is preferably 1% by mass or more and 37% by mass or less, calculated as ZnO. The lower limit of the Zn content can be 2.5% by mass or more, calculated as ZnO, or 7.0% by mass or more. The upper limit of the Zn content can be 30% by mass or less, calculated as ZnO, or 25% by mass or less.

[0022] The sintered body of this embodiment can be used as a PVD (physical vapor deposition) material, and can be used, for example, as a sputtering target, a vacuum deposition material, an ion plating material, etc. When used as a sputtering target, it can be formed into a disk-shaped plate, a rectangular plate, or a cylindrical shape, and can be bonded to a backing plate with a bonding material. When used as a sputtering target, its thickness can be 20 mm or less, preferably 3.0 to 15 mm, and more preferably 3.0 to 12 mm. The area of ​​the sputtered surface (sputtering surface) is 44 cm ２ It is preferable that the diameter is 75 mm or more.

[0023] A method for producing a sintered body, particularly a sputtering target, according to this embodiment will be described. However, the following production conditions are not limited to the disclosed range, and it is clear that some omissions and modifications may be made. In addition, detailed descriptions of well-known production steps and processing operations will be omitted to avoid unnecessarily obscuring the disclosed production method.

[0024] (1. Raw Material Powder) As the raw material powder, indium oxide (In ２ O ３ ) powder and zinc oxide (ZnO) powder are prepared. ２ O ３ The powder has a median diameter (D50): 0.5 to 3.0 μm and a specific surface area: 4.0 to 10 m２ / g, and the ZnO powder preferably has a median diameter (D50): 0.1 to 2.0 μm. The raw material powder preferably has a purity of 99.9 mass% or more. The raw material powder may be calcined at 1000°C to 1300°C. Calcination reduces uneven mixing in subsequent processes and increases uniformity.

[0025] (2. Mixing and Grinding Step) The above raw material powders are weighed out to achieve the desired composition ratio (content ratio of the sintered body), and mixed and pulverized. There are various pulverization methods depending on the desired particle size and the material to be pulverized, and wet or dry ball mills, vibration mills, bead mills, etc. can be used. To obtain uniform and fine crystal particles, a wet bead mill mixing method is preferred, as it has high efficiency in breaking down agglomerates in a short time and also ensures good dispersion of additives. It is preferable that the median diameter (D50) after pulverization is 0.1 to 1.0 μm.

[0026] (3. Sieving step) The pulverized slurry may be dried and further sieved using a sieve to break down agglomerations during drying. If the mesh size of the sieve is 500 μm or less, agglomerations can be broken down. The smaller the mesh size, the more agglomerations can be broken down, and by setting the mesh size to 250 μm or even 150 μm, agglomerations can be broken down even more. On the other hand, if the mesh size is too small, the work may become complicated.

[0027] (4. Sintering Process) Next, the mixed powder is sintered. Conventionally, sintering has been performed in air or an oxygen gas atmosphere at approximately 1400 to 1600°C. However, as the sintering temperature increases, grain growth occurs, resulting in a decrease in Vickers hardness. Furthermore, the volume resistivity increases, causing arcing and particle generation during sputtering, making stable sputtering difficult. Stabilizing sputtering is particularly important when sputtering targets become larger and uniform film deposition is desired using high-power sputtering.

[0028] In the manufacturing method of the present disclosure, pressure sintering is preferred from the viewpoint of increasing the relative density at a relatively low temperature. Hot press sintering or SPS (spark plasma sintering) can be used for pressure sintering. Regarding the atmosphere during sintering, sintering is preferably performed under an inert gas atmosphere rather than a vacuum from the viewpoint of suppressing the sublimation of ZnO. Furthermore, when sintering is performed under an inert gas atmosphere without pressure (atmospheric pressure), In ２ O ３ Therefore, pressure sintering is preferred from the viewpoint of being able to suppress reduction to some extent, and hot press sintering is particularly preferred from the viewpoint of productivity.

[0029] (4-1. Metallic Member) The maximum sintering temperature in the sintering process is 1100°C to 1300°C. Normally, when pressure sintering is performed at 1100°C or higher, In ２ O ３ However, in the manufacturing method disclosed herein, a metal member is placed between the sintering device member and the raw material powder, preventing reduction of the material and enabling high-temperature pressure sintering. If the maximum sintering temperature is less than 1100°C, pores may remain in the sintered body, while if the maximum sintering temperature is too high, grain growth occurs, leading to a decrease in the hardness of the sintered body. Since some types of metal member may reduce the sintering raw materials, it is necessary to use a metal material that forms a metal oxide with a higher standard Gibbs energy of formation than the sintering raw materials. For example, Mo, Ni, Co, etc. can be used as the metal member.

[0030] As described above, the manufacturing method according to this embodiment is to prevent a reduction reaction during sintering by placing a metal member between the sintering device member and the target raw material. This prevents the target raw material (In) from being reduced by the sintering device member (carbon). ２ O ３ , ZnO mixed powder), especially In ２ O ３ It is possible to prevent the reduction of

[0031] (4-2. Pressing pressure) The pressing pressure during pressure sintering was 150 kgf / cm２ It is preferable that the pressing pressure is 150 kgf / cm or more. ２ If the pressure is less than this, the density of the sintered body may decrease. Although there is no particular upper limit, it is set to 400 kgf / cm2 in view of the strength of the members used in pressure sintering. ２ It is preferable that:

[0032] (4-3. Sintering Holding Time) The holding time at the maximum sintering temperature is preferably within 6 hours. A shorter holding time is preferable because it increases productivity, but if the holding time is too short, it becomes difficult to obtain a high-density sintered body. As described above, the manufacturing method of the present disclosure enables sintering at a relatively high temperature, and therefore the holding time can be shortened accordingly, making it possible to significantly improve productivity.

[0033] (4-4. HIP Treatment) After pressure sintering, the obtained sintered body may be subjected to HIP (hot isostatic pressing). The HIP treatment is preferably carried out at a temperature of 900°C or higher and 1300°C or lower. The pressure is preferably 1000 kgf / cm. ２ More than 1800kgf / cm ２ The treatment time is preferably 1 hour or more and 10 hours or less.

[0034] (5. Finishing) The sintered body obtained through the above sintering process can be processed into a desired shape using a processing machine such as a surface grinder, a cylindrical grinder, or a machining device, as needed, and the surface can be polished to form a sputtering surface. There are no particular restrictions on the shape of the sputtering target, and it can be a flat disk, a rectangle, a cylinder, or the like. Furthermore, the sputtering target can be bonded to a backing plate for use as needed.

[0035] The following description will be given based on examples and comparative examples. Note that these examples are merely examples and are not intended to limit the scope of the present invention. That is, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in this disclosure.

[0036] The evaluation methods used in the examples and comparative examples are as follows. Note that, since sputtering targets are processed by grinding, polishing, etc., the sintered body (surface) after polishing is in substantially the same state as the sputtering target (sputtering surface). In addition, various evaluations are performed on a portion (sample) representative of the sintered body. If the various physical properties of a representative sample fall within the ranges of the present disclosure, the sintered body is encompassed by the present invention. In other words, even if a unique, exceptional, or partial sample that is not representative of the sintered body is measured and falls outside the range of the present disclosure, if the various physical properties of the representative sample fall within the ranges of the present disclosure, the sintered body is encompassed by the present invention as long as it exhibits the effects of the present invention. (Regarding composition analysis) The composition of the sintered body was analyzed using the following apparatus. Apparatus: SPS3500DD manufactured by SII Corporation Method: ICP-OES (inductively coupled plasma optical emission spectroscopy)

[0037] (Regarding relative density) The relative density was calculated using the following formula: Relative density (%) = Archimedes density / Calculated density × 100 Archimedes density: A measurement sample was prepared by grinding the sintered body so as to remove the affected layers on the top, bottom, and outer peripheral surfaces, and the Archimedes density was calculated using the Archimedes method. Calculated density: The sintered body was subjected to a component analysis, and the oxide mass ratio (mass%) was calculated by converting the atomic ratio (at%) of In and Zn to the total of 100 at% of the constituent elements In and Zn obtained by the component analysis, and the In mass ratio (mass%) shown below was also calculated. ２ O ３ , and the theoretical density of ZnO to calculate the calculated density. ３ )=(W1+W2) / (W1 / d1+W2 / d2) W1:In ２ O ３ W2: Mass ratio of ZnO (mass%) Theoretical density: d1: 7.18 g / cm ３ (In ２ O ３ Theoretical density) d2: 5.61 g / cm ３ (Theoretical density of ZnO)

[0038] (Regarding the average crystal grain size) A sample for observation was cut out from the sintered body, and the surface of the cut out sample was polished. A micrograph of the mirror-polished sample surface (a cross section perpendicular to the surface corresponding to the sputtered surface) was taken at 5000x magnification using a scanning electron microscope (SEM). Next, three lines (referred to as lines 1, 2, and 3) were drawn on the photographed image so that the number of crystal grains crossed by each line was 10 or more. The length of each line and the number of crystal grains crossed by each line were determined. At this time, crystal grains within the ends of the lines were counted as 0.5. Based on the measured length of the lines and the number of crystal grains crossed by each line, the crystal grain size in one field of view was calculated using the following formula: Crystal grain size in one field of view = (length of line 1 / number of crystal grains crossed by line 1 + length of line 2 / number of crystal grains crossed by line 2 + length of line 3 / number of crystal grains crossed by line 3) ÷ 3. Then, the crystal grain size was calculated for each of the six fields of view using the above formula, and the arithmetic average value of the six fields of view was taken as the average crystal grain size. However, if the number of crystal grains intersected by each straight line within the field of view is less than 10, a magnification of 2000x or 1000x may be used. The equipment used and measurement conditions were as follows: Equipment used: JXA-8500F (manufactured by JEOL Ltd.) Acceleration voltage: 15.0 kV Beam current: 5.0 x 10 －８ A

[0039] (Regarding pore area ratio) A sample for observation (10 mm x 10 mm x thickness: 3 to 20 mm) was cut out from the center of the sintered body, and a cross section perpendicular to the surface corresponding to the sputtering surface of the sputtering target was mirror-polished. A backscattered electron image of the mirror-polished sample surface was taken at 2000x magnification (100 μm x 100 μm) using the following scanning electron microscope (SEM). At this time, it is preferable to set the total number of pixels of the image to 750,000 or more. Apparatus used: JXA-8500F (manufactured by JEOL Ltd.) Acceleration voltage: 15.0 kV Beam current: 5.0 x 10 －８ A Total number of pixels: 1,209,600 pixels (horizontal: 1,280, vertical: 945)

[0040] The captured images were analyzed using ImageJ (image processing software). A reference diagram for ImageJ analysis is shown in Figure 1 (left: SEM micrograph, right: ImageJ image analysis diagram). As shown in Figure 1, analysis using ImageJ makes it possible to count the frequency An of the brightness n (range 0 to 255) of the captured image.

[0041] For structures with two or more crystalline phases, the brightest crystalline phase (In ２ O ３ The brightness (n1) at which the frequency An of the portion corresponding to the darkest crystalline phase (In ２ O ３ Three images were randomly selected, with a brightness (n2) of 75≦n2≦90, at which the frequency An of the portion corresponding to the phase with a low ratio was at its maximum. Since accurate measurement is not possible with images that contain blown-out highlights, images with a frequency An of An<1000 or less when the brightness n is 250-255 were selected.

[0042] Next, the three selected images were converted to 8-bit display using ImageJ, and then binarized using the threshold function. The minimum threshold value was set to 0, and the maximum threshold value was set to a range of 10 to 55, so that only pores were displayed in black. Figure 2 shows reference images before (left) and after (right) binarization. In IZO sintered bodies, pores exist only at the grain boundaries between crystal grains, so a maximum threshold value can be set so that the interior of the crystal grains is not displayed in black, and only the pores at the grain boundaries are displayed in black.

[0043] The number of black parts counted from the obtained binarized image (A ｐｏｒｅ ) and the count of the white part (A ｂｕｌｋ The pore area ratio was calculated using the following formula, and the arithmetic mean value of the three images was used. (Pore area ratio) = A ｐｏｒｅ / (A ｐｏｒｅ +A ｂｕｌｋ ) x 100 [%]

[0044] For monophasic tissue, the maximum frequency An ｍａｘ The brightness (n ｍａｘ) is 140≦n ｍａｘ ≦160, and the count number is the maximum frequency An ｍａｘ The darkest brightness (n ｈａｌｆ ) is 130≦n ｈａｌｆ Three images were selected that achieved An≦135. Since accurate measurement is not possible with images that have blown-out highlights, images with An<1000 when the brightness n is between 250 and 255 were selected.

[0045] The three selected images are binarized using ImageJ in the same way as when two or more crystalline phases are present. From the obtained binarized images, the count number of black areas (A ｐｏｒｅ ) and the count of the white part (A ｂｕｌｋ The pore area ratio was calculated using the following formula, and the arithmetic mean value of the three images was used. (Pore area ratio) = A ｐｏｒｅ / (A ｐｏｒｅ +A ｂｕｌｋ ) x 100 [%]

[0046] (Volume Resistivity) The surface of a sintered body with a diameter of 160 mm was polished, and the volume resistivity was measured at any five points on the polished surface spaced at least 1.5 cm apart, and the arithmetic mean value and standard deviation of the five points were calculated. The following equipment was used for the measurement. Equipment: Resistivity Meter Σ-5+ manufactured by NPS Co., Ltd. Method: Constant current application method Method: DC four-probe method Measurement temperature: Room temperature (20 to 25°C)

[0047] (Regarding Vickers Hardness) A sample was cut out from the sintered body, the surface of the cut sample was polished, and the Vickers hardness of the polished surface was measured in accordance with JIS R 1610: 2003. Test method: Vickers hardness test Apparatus: Micro Vickers hardness tester (Mitutoyo HM-200D) Test force: 4.903 N Test temperature: 10 to 35°C Load time: 1 to 5 seconds Hold time: 15 seconds Unload time: 4 seconds Approach speed: 60 μm / sec Distance between indentations: 4 times or more the average diagonal length of the indentations The number of tests was 5, and the average value was calculated.

[0048] (Regarding chroma) A sample was cut out from the sintered body, and the surface of the cut sample was polished. The polished surface was measured using a NIPPON DENSHOKU INDUSTRIES CO., LTD. (Model: NF333). ＊ a ＊ b ＊ The measurement was performed. ＊ represents the brightness, and a ＊ , b ＊ represents chromaticity. Saturation C ＊ (C ＊ ) = {(a ＊ ) ２ +(b ＊ ) ２} １／２ (Measurement conditions) Illumination and light receiving conditions: 0°: 45° (0° illumination: 45° circular light receiving) Measurement method: Double beam method, spectroscopic method Measurement wavelength: 400 nm to 700 nm (output at 20 nm intervals) Measurement light source: D65 Observation conditions: 2° field of view for each measurement light source Five measurements were taken and the average value was calculated.

[0049] (Example 1) In ２ O ３ Powder and ZnO powder were prepared, weighed and mixed to obtain the composition shown in Table 1, and then calcined at 1100°C. The mixture was then pulverized in a wet bead mill to a median diameter D50 of 0.37 μm. The resulting mixed powder was then filled into a carbon die. To prevent the mixed powder from coming into contact with the carbon die and being reduced during sintering, a metal member was placed at the point where the mixed powder would come into contact with the carbon die. The mixture was then sintered in an argon atmosphere at a maximum sintering temperature of 1150°C and a press pressure of 300 kgf / cm. ２ The physical properties of the sintered body obtained in Example 1 were measured, and the results were an average crystal grain size of 0.77 μm, a relative density of 100.0%, a volume resistivity of 1.01 mΩ·cm, a pore area ratio of 0.15%, a Vickers hardness of 699 HV, and a saturation of C ＊ A good result of 0.85 was obtained.

[0050]

[0051] (Example 2) In ２ O３ Powder and ZnO powder were prepared, weighed and mixed to obtain the composition shown in Table 1, and then pulverized under the same conditions as in Example 1. Next, the obtained mixed powder was filled into a carbon die, and hot press sintering was carried out under the same conditions as in Example 1 to produce a sintered body. However, in Example 2, unlike Example 1, the ratio of ZnO was changed and the maximum sintering temperature was set to 1150°C. Measurement of the physical properties of the sintered body obtained in Example 2 showed an average crystal grain size of 1.30 μm, a relative density of 99.1%, a volume resistivity of 2.39 mΩ cm, a pore area ratio of 0.10, a Vickers hardness of 714 HV, and a chroma C ＊ A good result of 1.53 was obtained.

[0052] (Example 3) In ２ O ３ Powder and ZnO powder were prepared, weighed and mixed to obtain the composition shown in Table 1, and then pulverized under the same conditions as in Example 1. Next, the obtained mixed powder was filled into a carbon die, and hot press sintering was carried out under the same conditions as in Example 1 to produce a sintered body. However, in Example 3, unlike Example 1, the ratio of ZnO was changed and the maximum sintering temperature was set to 1200°C. Measurement of the physical properties of the sintered body obtained in Example 3 showed an average crystal grain size of 1.05 μm, a relative density of 99.1%, a volume resistivity of 1.11 mΩ cm, a pore area ratio of 0.11, a Vickers hardness of 549 HV, and a chroma C ＊ A good result of 1.99 was obtained.

[0053] (Comparative Example 1) In ２ O ３ Powder and ZnO powder were prepared, weighed and mixed to obtain the composition shown in Table 1, and then pulverized under the same conditions as in Example 1. Next, the obtained mixed powder was filled into a carbon die, and hot press sintering was carried out under the same conditions as in Example 1 to produce a sintered body. However, in Comparative Example 1, unlike Example 1, no metal member was provided to prevent reduction of the mixed powder, and the maximum sintering temperature was 1000°C and the pressing pressure was 300 kgf / cm. ２ The holding time was 3 hours, and the other conditions were the same. When the physical properties of the sintered body obtained in Comparative Example 1 were measured, it was found that the relative density was low and the desired results were not obtained.

[0054] (Comparative Example 2) In ２ O ３ Powder and ZnO powder were prepared, weighed and mixed to obtain the composition shown in Table 1, and then pulverized under the same conditions as in Example 1. The pulverized slurry was granulated, and the resulting mixed powder was filled into a die and pressed under a pressure of 785 kfg / cm. ２ , holding time: 1 minute, uniaxial molding, then press pressure: 1795 kgf / cm ２ A green body was produced by CIP molding with a holding time of 1 minute. The green body was then subjected to atmospheric sintering in an air atmosphere at a maximum sintering temperature of 1400°C and a holding time of 10 hours to produce a sintered body. Measurement of the physical properties of the sintered body produced in Comparative Example 2 revealed that the relative density was low and the average crystal grain size was 2.36 μm, which was not the desired result.

[0055] According to the present disclosure, it is possible to provide a sintered body containing indium, zinc, and oxygen, which has a small average crystal grain size and high density, and a sputtering target. Furthermore, according to the present disclosure, particle generation during sputtering can be suppressed, potentially improving product yield. Improving product yield leads to a stable supply of products and reduced loss of metal raw materials, which are limited resources. Therefore, the present disclosure may contribute to Goal 9 "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster technological innovation" and Goal 12 "Ensure sustainable consumption and production patterns" of the United Nations-led Sustainable Development Goals (SDGs). The sintered body and sputtering target according to the present disclosure are useful for forming IZO thin films as transparent conductive films and oxide semiconductor films.

Claims

1. A sintered body containing indium, zinc, and oxygen, with an average crystal grain size of 2 μm or less and a relative density of 99% or more.

2. The sintered body according to claim 1, wherein the pore area ratio is 0.25% or less.

3. The sintered body according to claim 1 or 2, which has a Vickers hardness of 500 HV or more.

4. The sintered body according to any one of claims 1 to 3, which has a volume resistivity of 5 mΩ·cm or less.

5. Saturation C ＊ 5. The sintered body according to claim 1, wherein the sintered body has a tensile strength of 2.0 or less.

6. A sintered body according to any one of claims 1 to 5, wherein the Zn content is 1% by mass or more and 37% by mass or less in terms of ZnO.

7. A sputtering target comprising the sintered body according to any one of claims 1 to 6.

8. The area of ​​the sputtering surface is 44 cm ２ The sputtering target according to claim 7 .

9. In ２ O ３ A method for producing a sintered body includes mixing a ZnO powder with a ZnO powder, filling the resulting mixed powder into a sintering apparatus, placing metal members constituting a metal oxide having a higher standard Gibbs energy of formation than the mixed powder around the mixed powder in the sintering apparatus, and hot pressing the resulting sintered body.

10. The mixed powder is sintered under vacuum or inert gas atmosphere at a maximum sintering temperature of 1100 to 1300°C and a pressing pressure of 150 kgf / cm. ２ The method for producing a sintered body according to claim 9, wherein hot pressing is carried out under the above conditions.

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