Sintered body and sputtering target and method for producing sintered body

Abstract

The present disclosure provides an IZO sintered body containing indium, zinc, and oxygen, having a small crystal grain size and a high density, and a method for producing the same. 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.

Description

Technical Field

[0001] This disclosure relates to sintered bodies and sputtering targets, as well as methods for manufacturing sintered bodies. Background Technology

[0002] Thin films of indium oxide-tin oxide (ITO) and indium oxide-zinc oxide liquid oxide (IZO), which are primarily composed of indium oxide, possess high conductivity and transmittance in the visible light region, and are therefore used as electrode materials for various flat panel displays. In particular, regarding IZO, stable amorphous films with low resistance and high transmittance can be obtained through room temperature deposition, exhibiting good etching characteristics and high film flatness. Furthermore, IZO possesses characteristics as an oxide semiconductor, and its application as a channel layer in TFTs has been investigated.

[0003] Sputtering methods using sputtering targets manufactured from IZO sintered bodies have been widely used as a method for forming IZO films. Several reports exist regarding IZO sintered bodies. Patent Document 1 illustrates a technique for reducing bulk resistivity by adding trace amounts of tin to IZO. This technique utilizes tin as a dopant, demonstrating that bulk resistivity decreases with increasing tin concentration; however, the density of the sintered body is not a primary concern.

[0004] Furthermore, Patent Document 2 discloses the following technique: pre-calcining a mixture of In2O3 and ZnO powder under appropriate conditions to suppress the rapid occurrence of phase change, thereby improving the properties of the sintered body, such as increasing density.

[0005] Furthermore, Patent Document 3 discloses the following technique: HIP (Hot Isostatic Pressing) treatment is performed on the sintered IZO, thereby allowing the gas in the pores generated in the IZO sintered body to be discharged along the grain boundaries, resulting in a sintered body with fewer pores and greater density.

[0006] Existing technical documents Patent documents Patent Document 1: Japanese Patent No. 3721080 Patent Document 2: Japanese Patent No. 6078189 Patent Document 3: Japanese Patent No. 6523510 Summary of the Invention

[0007] The problem that the invention aims to solve In IZO sintered bodies containing indium, zinc, and oxygen, high density sintering at atmospheric pressure requires sintering conditions above 1400°C for approximately 10 hours. However, due to the high temperature and long sintering time, grain coarsening occurs, leading to a decrease in the strength of the sintered body. In view of the above problems, the technical problem of this disclosure is to provide an IZO sintered body containing indium, zinc, and oxygen, with small grain size and high density, a sputtering target, and a method for manufacturing the sintered body.

[0008] Solution for solving the problem In order to solve the above-mentioned technical problems, the inventors conducted in-depth research and found that by improving the manufacturing method of sintered bodies containing indium, zinc and oxygen, sintered bodies with small crystal grain size and high density can be obtained.

[0009] That is, the main point of this disclosure is as follows.

[0010] [1] A sintered body containing indium, zinc and oxygen, having an average crystal grain size of less than 2 μm and a relative density of more than 99%.

[0011] [2] The sintered body according to [1], wherein the porosity is less than 0.25%.

[0012] [3] The sintered body according to [1] or [2], wherein the Vickers hardness is 500 HV or higher.

[0013] [4] The sintered body according to any one of [1] to [3], wherein the volume resistivity is less than 5 mΩ·cm.

[0014] [5] The sintered body according to any one of [1] to [4], wherein the saturation C * It is below 2.0.

[0015] [6] The sintered body according to any one of [1] to [5], wherein the Zn content is 1% by mass or more and 37% by mass or less when converted to ZnO.

[0016] [7] A sputtering target, which is composed of a sintered body as described in any one of [1] to [6].

[0017] [8] According to the sputtering target described in [7], the area of ​​the sputtering surface is 44 cm². 2 above.

[0018] [9] A method for manufacturing a sintered body, wherein In2O3 powder and ZnO powder are mixed, the resulting mixed powder is filled into a sintering apparatus, a metal component constituting a metal oxide with a standard generating Gibbs energy higher than that of the mixed powder is disposed around the mixed powder in the sintering apparatus, and hot pressing is performed.

[0019]

[10] The method for manufacturing the sintered body according to [9], wherein, under a vacuum or inert gas atmosphere, the maximum sintering temperature is 1100–1300 °C and the pressing pressure is 150 kgf / cm². 2 The mixed powder is hot-pressed under the above conditions.

[0020] Invention Effects According to this disclosure, a sintered body and sputtering target containing indium, zinc and oxygen, with a small average crystal grain size and high density can be provided. Attached Figure Description

[0021] Figure 1 These are microstructure photographs (SEM-based images) and image analysis diagrams of the sintered body (reference).

[0022] Figure 2 These are images before and after binarization used when calculating the porosity (reference). Detailed Implementation

[0023] The following are specific implementation schemes to illustrate this disclosure. However, each component and its combination in each implementation scheme is just an example. Appropriate additions, omissions, substitutions and other changes to the components may be made without departing from the spirit of this disclosure.

[0024] The sintered body of the embodiments disclosed herein (hereinafter also referred to as this embodiment) contains indium, zinc, and oxygen. A sintered body having such a composition is sometimes referred to as an IZO sintered body. It should be noted that IZO is an abbreviation based on the first letter of each of the constituent elements indium (In), zinc (Zn), and oxygen (O). IZO thin films are used as transparent conductive films, oxide semiconductors, and particularly as electrode materials in displays.

[0025] IZO thin films can typically be formed using sputtering. A sputtering target (sometimes called an IZO sputtering target) made of sintered IZO is placed in a vacuum chamber, and argon ions generated by glow discharge collide with the sputtering target at high speed, causing the ejected atoms to deposit on an opposing glass substrate, thereby forming a thin film with a composition approximately the same as that of the sputtering target.

[0026] The sintered body of the embodiments disclosed herein has an average crystal grain size of 2 μm or less. By refining the grains, the hardness of the sintered body can be improved. Furthermore, the generation of particles during sputtering can be suppressed. 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.

[0027] The relative density of the sintered body in this embodiment is 99% or higher. The higher the relative density of the sputtering target composed of the IZO sintered body, the greater the hardness of the sintered body. Furthermore, it can suppress the generation of particles during sputtering. IZO sintered bodies require a fine crystal structure; therefore, sintering at low temperatures that can suppress grain growth is preferred. On the other hand, it is difficult to obtain a high-density sintered body in low-temperature sintering. However, according to the manufacturing method of this disclosure, which is detailed later, grain growth can be suppressed, and a high-density sintered body can be obtained. A relative density of 99.5% or higher is preferred, and 99.9% or higher is more preferred.

[0028] In the sintered body of this embodiment, the porosity is preferably 0.25% or less. If the sputtering target has pores, particles will be generated during sputtering starting from those pores; therefore, it is preferable to minimize pores as much as possible. The porosity is more preferably 0.20% or less. The porosity is calculated according to the following formula.

[0029] Pore ​​area ratio = (Area of ​​the region equivalent to pores) / (Area of ​​the observed sintered body structure) × 100 The Vickers hardness of the sintered body in this embodiment is preferably 500 HV or higher. According to this disclosure, grain growth can be suppressed, thus suppressing the decrease in Vickers hardness. More preferably, it is 550 HV or higher. Further preferably, it is 600 HV or higher. Particularly preferably, it is 650 HV or higher. Increasing the Vickers hardness of the sintered body can suppress crack formation during high-power sputtering, and is therefore particularly effective. It should be noted that the Vickers hardness is affected by the Zn content (converted to ZnO) in the sintered body; the higher the Zn content (converted to ZnO), the lower the Vickers hardness.

[0030] The volume resistivity of the sintered body in this embodiment is preferably 5 mΩ·cm or less. If the volume resistivity is high, arcing will occur during sputtering, leading to particle formation; therefore, the resistivity is preferably as low as possible. If oxygen vacancies are generated in the sintered body, the volume resistivity decreases; therefore, the sintering conditions are adjusted to generate oxygen vacancies. The volume resistivity is preferably 2 mΩ·cm or less, more preferably 1 mΩ·cm or less.

[0031] When sintering in the atmosphere, no oxygen vacancies are generated in the sintered body, and the volume resistivity does not decrease significantly. However, when sintering is performed under conditions of low oxygen partial pressure, such as a vacuum or Ar atmosphere, oxygen vacancies are generated in the sintered body, the volume resistivity decreases, and the color of the sintered body also changes. Therefore, color can also be used to characterize sintered bodies. As a numerical indicator for quantifying the color of an object, L... * a * b * Color space. L * L represents brightness. * The closer to 100, the brighter (total internal reflection), L *The closer to 0, the dimmer (no reflection). Also consider using L... * The sintered body is determined, but L * The value varies greatly depending on the surface condition (surface roughness, etc.), therefore it is impossible to accurately determine the color. On the other hand, a * b represents the intensity of colors ranging from green to red. * The intensity and saturation (C) of colors ranging from blue to yellow. * According to (C) * ) = {(a * ) 2 + (b) * ) 2} 1 / 2 The saturation C was calculated. * With L * Unlike other colors, it is unaffected by surface conditions (reflection) and can control the intensity of colors. Based on this, it is preferable to use saturation C. * From the viewpoint of sputtering characteristics, the sintered body of this embodiment has a saturation C. * Preferably, it is 2.0 or less. More preferably, it is 1.5 or less, and even more preferably, it is 1.0 or less.

[0032] The sintered body of this embodiment contains indium (In), zinc (Zn), and oxygen (O), and the content of each is not particularly limited. However, the content of Zn affects the conductivity of the target film, so it is preferably set to 1% by mass or more and 37% by mass or less when converted to ZnO. The lower limit of the Zn content can be set to 2.5% by mass or more when converted to ZnO, and it can also be set to 7.0% by mass or more. The upper limit of the Zn content can be set to 30% by mass or less when converted to ZnO, and it can also be set to 25% by mass or less.

[0033] The sintered body of this embodiment can be used as a material for PVD (physical vapor deposition), such as a sputtering target, vacuum evaporation material, or ion plating material. When used as a sputtering target, it can be shaped like a disc plate, a rectangular plate, or a cylinder, and can be bonded to a backing plate using a bonding material. Furthermore, 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 sputtering surface (sputtering surface) is preferably 44 cm². 2 75mm or more in diameter.

[0034] The manufacturing method of the sintered body, particularly the sputtering target, according to this embodiment will be described. However, the manufacturing conditions and other details described below are not limited to the scope of the disclosure, and some omissions and modifications are obviously possible. It should be noted that, in order to avoid unnecessarily obscuring the disclosed manufacturing method, detailed descriptions of well-known manufacturing processes and handling operations are omitted.

[0035] (1. Raw material powder) Indium oxide (In₂O₃) powder and zinc oxide (ZnO) powder are prepared as raw material powders. The preferred In₂O₃ powder has a median particle size (D50) of 0.5–3.0 μm and a specific surface area of ​​4.0–10 m². 2 / g, median particle size (D50) of ZnO powder: 0.1~2.0μm. Furthermore, raw material powder with a purity of 99.9% by mass or higher is preferably used. Alternatively, the raw material powder can be pre-calcined at 1000℃~1300℃. Pre-calcination reduces mixing unevenness and increases uniformity in subsequent processes.

[0036] (2. Mixing and grinding process) The raw material powders are weighed to achieve the desired composition ratio (content ratio of the sintered body) and then mixed and pulverized. Various pulverization methods exist depending on the required particle size and the material being pulverized; wet or dry ball mills, vibratory mills, bead mills, etc., can be used. To obtain uniform and fine grains, a wet bead milling method is preferred due to its high efficiency in breaking up agglomerates in a short time and its good dispersion of additives. The median particle size (D50) after pulverization is preferably 0.1–1.0 μm.

[0037] (3. Screening process) After drying the pulverized slurry, further screening can be performed using a sieve to break up any agglomerates formed during drying. A sieve with a mesh size of 500 μm or less can effectively break up agglomerates. Smaller mesh sizes are more effective at breaking up agglomerates; setting the mesh size to 250 μm and then further to 150 μm can further improve this process. However, if the mesh size is too small, the process can sometimes become cumbersome.

[0038] (4. Regarding the sintering process) The mixed powder is then sintered. Previously, sintering was carried out in an atmospheric or oxygen atmosphere at around 1400–1600°C. However, if the sintering temperature is increased, grain growth and a decrease in Vickers hardness occur. Furthermore, the volume resistivity increases, leading to arcing and particle generation during sputtering, making stable sputtering difficult. Especially with the increasing size of sputtering targets and the desire for uniform film formation through high-power sputtering, sputtering stabilization is crucial.

[0039] In the manufacturing method disclosed herein, pressure sintering is preferred from the viewpoint of increasing the relative density at a lower temperature. As pressure sintering, hot pressing or SPS (Spark Plasma Sintering) can be used. Regarding the atmosphere during sintering, from the viewpoint of suppressing ZnO sublimation, sintering under an inert gas atmosphere is preferred compared to a vacuum. Furthermore, in an inert gas atmosphere, when sintering without pressure (at ambient pressure), In2O3 will be reduced, hindering the increase of the density of the sintered body, and sometimes contaminating the interior of the apparatus. Therefore, from the viewpoint of suppressing reduction to some extent, pressure sintering is also preferred, and in particular, from a production perspective, hot pressing sintering is preferred.

[0040] (4-1. Metal components) The maximum sintering temperature in the sintering process is set to 1100℃~1300℃. Normally, if pressure sintering is performed above 1100℃, In₂O₃ may react with carbon, which is a component of the sintering apparatus, and be reduced. In the manufacturing method disclosed herein, by placing a metal component between the sintering apparatus component and the raw material powder, reduction with the component can be prevented, allowing for high-temperature pressure sintering. If the maximum sintering temperature is below 1100℃, porosity may remain in the sintered body. On the other hand, if the maximum sintering temperature is excessively increased, grain growth will occur, leading to a decrease in the hardness of the sintered body. Depending on the type of metal component, sometimes the metal component itself reduces the sintering raw material; therefore, it is necessary to use a metal material that constitutes a metal oxide with a standard Gibbs energy higher than that of the sintering raw material. For example, Mo, Ni, Co, etc., can be used as the metal component.

[0041] As described above, the manufacturing method of this embodiment provides a metal component between the sintering apparatus component and the target material to prevent reduction reaction during sintering. As a result, the reduction of the target material (mixed powder of In2O3 and ZnO) caused by the sintering apparatus component (carbon), especially In2O3, can be prevented.

[0042] (4-2. Suppressing pressure) The pressing pressure in pressure sintering is preferably set to 150 kgf / cm. 2 The above. If the pressing pressure is less than 150 kgf / cm². 2 If the density of the sintered body is lowered, the upper limit may decrease. Furthermore, while no specific upper limit is specified, considering the strength of components used for pressure sintering, a value of 400 kgf / cm² is preferred. 2 the following.

[0043] (4-3. Sintering holding time) The holding time at the highest sintering temperature is preferably set to within 6 hours. A shorter holding time improves productivity and is therefore preferred; however, if the holding time is short, it is difficult to obtain a high-density sintered body. In the manufacturing method of this disclosure, as described above, sintering at a relatively high temperature can be performed, and correspondingly, the holding time can be shortened, significantly improving productivity.

[0044] (4-4. HIP processing) After pressure sintering, the resulting sintered body can be subjected to HIP (hot isostatic pressing) treatment. HIP treatment is preferably performed at a temperature above 900°C and below 1300°C. Furthermore, a pressure of 1000 kgf / cm² is preferred. 2 Above and 1800 kgf / cm 2 The processing time is set to be more than 1 hour and less than 10 hours.

[0045] (5. Regarding finishing) The sintered body obtained through the above sintering process can be machined into the desired shape using surface grinders, cylindrical grinders, machining, or other processing machines. Furthermore, the surface can be polished to create a sputtering surface. The shape of the sputtering target is not particularly limited; it can be made into a flat disc, rectangular shape, cylindrical shape, etc. Additionally, the sputtering target can be joined with a backing plate as needed.

[0046] Example The following description is based on embodiments and comparative examples. It should be noted that this embodiment is merely an example and is not intended to limit the invention in any way. That is, the invention is limited only by the claims and includes various modifications other than those included in this disclosure.

[0047] The evaluation methods used in the examples and comparative examples are described below. It should be noted that the sputtering target is processed by grinding, polishing, etc., of the sintered body; therefore, the polished sintered body (surface) is in a substantially identical state to the sputtering target (sputtering surface). Furthermore, various evaluations are performed on representative portions (samples) of the sintered body. If the various physical properties of the representative sample are included within the scope of this disclosure, the sintered body is included in this invention. That is, even if the measurement of a sample that is not specific, exceptional, or localized like the sintered body and thus falls outside the scope of this disclosure, if the various physical properties of the representative sample are included within the scope of this disclosure, the sintered body is included in this invention as long as it achieves the effects of this invention.

[0048] (Regarding composition analysis) The composition of the sintered body was analyzed using the following apparatus.

[0049] Device: SII SPS3500DD Method: ICP-OES (Inductively Coupled Plasma Emission Spectroscopy).

[0050] (Regarding relative density) The relative density is calculated using the following formula.

[0051] Relative density (%) = Archimedes density / calculated density × 100 Archimedes density: The Archimedes density is calculated by grinding the upper and lower surfaces and the outer peripheral surface of the sintered body to remove the altered layer.

[0052] Calculated density: The compositional analysis of the sintered body was performed, and the calculated density was obtained by converting the mass ratio (mass%) of the oxides based on the atomic ratio (at%) of each of the constituent elements In and Zn relative to a total of 100 at% of In and Zn, and the theoretical densities of In2O3 and ZnO shown below.

[0053] Calculate density (g / cm³) 3 )=(W1+W2) / (W1 / d1+W2 / d2) W1: Mass ratio of In2O3 (mass%) W2: Mass ratio of ZnO (mass%).

[0054] Theoretical density: d1: 7.18 g / cm³ 3 (Theoretical density of In2O3) d2: 5.61 g / cm³ 3 (Theoretical density of ZnO).

[0055] (Regarding average crystal grain size) An observation sample was cut from the sintered body, and the surface of the cut sample was polished. A scanning electron microscope (SEM) was used to take microscopic images of the mirror-polished sample surface (a cross-section perpendicular to the plane corresponding to the sputtering surface) at 5000x magnification, with six fields of view. Next, three straight lines (designated as lines 1, 2, and 3) were drawn on the images, each traversing at least 10 grains. The length of each line and the number of grains traversed by each line were determined. At this point, the grain count inside the grain at the end of the line was 0.5.

[0056] Based on the measured length of the straight lines and the number of grains that each line crosses, the grain size in one field of view is calculated using the following formula.

[0057] The grain size in one field of view = (length of line 1 / number of grains traversed by line 1 + length of line 2 / number of grains traversed by line 2 + length of line 3 / number of grains traversed by line 3) ÷ 3 Then, for each of the six fields of view, the crystal grain size is calculated using the above formula, and the arithmetic mean of the six fields of view is taken as the average crystal grain size. Where the number of grains traversed by each straight line within a field of view is not more than 10, a magnification of 2000x or 1000x can be used. It should be noted that the apparatus and measurement conditions are as follows.

[0058] Device used: JXA-8500F (manufactured by Nippon Electronics Co., Ltd.) Accelerating voltage: 15.0kV Beam current: 5.0 × 10 －8 A.

[0059] (Regarding porosity) A sample for observation (10mm × 10mm × thickness: 3–20mm) is cut from the center of the sintered body. The cross-section perpendicular to the sputtering surface of the sputtering target is mirror-polished. A reflectance electron image of the mirror-polished sample surface is then captured at 2000x magnification (100μm × 100μm) using a scanning electron microscope (SEM). Ideally, the total pixel count of the image should be set to 750,000 pixels or higher.

[0060] Device used: JXA-8500F (manufactured by Nippon Electronics Co., Ltd.) Accelerating voltage: 15.0kV Beam current: 5.0 × 10 －8 A Total number of pixels: 1,209,600 pixels (width: 1280, height: 945).

[0061] Image analysis was performed on the captured images using ImageJ (an image processing software). The ImageJ analysis reference diagram is shown below. Figure 1 (Left image: Tissue photograph based on SEM; Right image: Image analysis based on ImageJ). For example... Figure 1 As shown, in ImageJ-based parsing, the frequency of the brightness of the captured image, n (in the range of 0 to 255), can be counted.

[0062] For structures containing two or more crystalline phases, arbitrarily select three images as follows: In these images, the frequency An corresponding to the brightest crystalline phase (the phase with a high proportion of In₂O₃) is considered the maximum brightness (n₁) at 160 ≤ n₁ ≤ 175; the frequency An corresponding to the darkest crystalline phase (the phase with a low proportion of In₂O₃) is considered the maximum brightness (n₂) at 75 ≤ n₂ ≤ 90. Accurate measurement is not possible in images with high light overflow; therefore, when the brightness n is between 250 and 255, images with a frequency An < 1000 are selected.

[0063] Next, the three selected images were converted to 8-bit display using ImageJ, and then binarized using a thresholding function. The minimum threshold value was set to 0, and the maximum threshold value was set to the range of 10 to 55, with only the pores displayed in black. Figure 2 The image shows reference images before (left) and after (right) binarization. It should be noted that in the sintered body of IZO, pores exist only at the grain boundaries between grains. Therefore, a maximum threshold can be set so that the grains themselves are not displayed as black, and only the pores at the grain boundaries are displayed as black.

[0064] Read the count of the black portion from the obtained binarized image (A pore ) and the count of the white parts (A) bulk The pore area ratio is calculated using the following formula, which is the arithmetic mean of three images.

[0065] (Porosity) = A pore / (A pore +A bulk ) × 100 [%] Regarding the single-phase tissue, three images are selected below, in which the maximum frequency An is [missing information]. max Brightness (n) max ) is 140≤n max ≤160, and the count is the maximum frequency An max Of the brightness values ​​above 1 / 2, the darkest brightness (n) half ) is 130≤n half ≤135. At this point, accurate measurement is not possible in images with highlight overflow. Therefore, when the brightness n is 250 to 255, images with An < 1000 are selected.

[0066] Regarding the three selected images, similar to the case where more than two crystalline phases exist, image binarization was performed using ImageJ. The count of the black portion (A) was then read from the resulting binarized image. pore ) and the count of the white parts (A) bulkThe pore area ratio is calculated using the following formula, which is the arithmetic mean of three images.

[0067] (Porosity) = A pore / (A pore +A bulk ) × 100 [%] (Regarding volume resistivity) The surface of a sintered body with a diameter of 160 mm was polished. The volume resistivity was measured at five arbitrary points on the polished surface, spaced at intervals of more than 1.5 cm. The arithmetic mean and standard deviation of these five points were calculated. The following apparatus was used for the measurement.

[0068] Apparatus: NPS resistivity meter Σ-5+ Method: Constant current application Method: DC four-probe method Measurement temperature: room temperature (20-25℃).

[0069] (Regarding Vickers hardness) The sample was cut from the sintered body, and the surface of the cut sample was polished. The Vickers hardness of the polished surface was measured according to JIS R 1610:2003.

[0070] Test method: Vickers hardness test Apparatus: Micro Vickers hardness tester (Mitutoyo HM-200D) Test force: 4.903 N Test temperature: 10~35℃ Loading time: 1-5 seconds Duration: 15 seconds Uninstallation time: 4 seconds Approach speed: 60 μm / s Indentation spacing: more than 4 times the average length of the diagonal of the indentation.

[0071] Set the number of trials to 5 and calculate the average value.

[0072] (Regarding saturation) Samples were cut from the sintered body, and the surface of the cut samples was polished. The L value of the polished surface was measured using a Nippon Denshoku Kogyo Co., Ltd. (model: NF333). * a * b * It should be noted that L * Indicates brightness, a * b * Indicates chromaticity. According to (C... * ) = {(a * ) 2 + (b)* ) 2} 1 / 2 The saturation C is calculated using the formula. * .

[0073] (Measurement conditions) Lighting / Light Reception Conditions: 0°: 45° (0° lighting: 45° circumferential lighting) Measurement method: Dual-beam mode Wavelength measured by front-spectrum method: 400nm~700nm (output in 20nm intervals) Measurement light source: D65 Observation conditions: 2° field of view for each light source.

[0074] Set the number of measurements to 5 and calculate the average value.

[0075] (Example 1) In₂O₃ powder and ZnO powder were prepared, weighed and mixed as shown in Table 1, and pre-calcined at 1100°C. Then, the mixture was pulverized using a wet bead mill to achieve a median particle size D50 of 0.37 μm. Next, the resulting mixed powder was filled into a carbon mold. To prevent the mixed powder from contacting the carbon mold and reducing it during sintering, metal components were placed at the contact points. Then, under an argon atmosphere, sintering was performed at a maximum sintering temperature of 1150°C and a pressing pressure of 300 kgf / cm². 2 Holding time: Hot pressing sintering was performed for 6 hours to produce a sintered body. The physical properties of the sintered body obtained in Example 1 were measured, and the results showed that the average crystal grain size was 0.77 μm, the relative density was 100.0%, the volume resistivity was 1.01 mΩ·cm, the porosity was 0.15%, the Vickers hardness was 699 HV, and the degree of saturation was C. * The value was 0.85, which yielded a good result. (Example 2) In₂O₃ powder and ZnO powder were prepared, weighed and mixed to form the composition described in Table 1, and then pulverized under the same conditions as in Example 1. Next, the resulting mixed powder was filled into a carbon mold and hot-pressed and sintered 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. The physical properties of the sintered body obtained in Example 2 were measured, and the results 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 porosity of 0.10, a Vickers hardness of 714 HV, and a degree of saturation of C. * The value was 1.53, which yielded a good result.

[0076] (Example 3) In₂O₃ powder and ZnO powder were prepared, weighed and mixed to achieve the composition described in Table 1, and then pulverized under the same conditions as in Example 1. Next, the resulting mixed powder was filled into a carbon mold and hot-pressed and sintered 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. The physical properties of the sintered body obtained in Example 3 were measured, and the results 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 porosity of 0.11, a Vickers hardness of 549 HV, and a degree of saturation of C. * The value was 1.99, which yielded a good result.

[0077] (Comparative Example 1) In₂O₃ powder and ZnO powder were prepared, weighed and mixed to form the composition described in Table 1, and then pulverized under the same conditions as in Example 1. Next, the resulting mixed powder was filled into a carbon mold, and hot-pressed and sintered under the same conditions as in Example 1 to produce a sintered body. However, unlike Example 1, in Comparative Example 1, no metal components were provided to prevent the mixed powder from being reduced. Furthermore, the maximum sintering temperature was set to 1000°C and the pressing pressure to 300 kgf / cm². 2 Holding time: 3 hours, other conditions were the same as in Example 1. The physical properties of the sintered body obtained in Comparative Example 1 were measured, and the results showed that the relative density was low, which was not the expected result.

[0078] (Comparative Example 2) Prepare In₂O₃ powder and ZnO powder, weigh and mix them to achieve the composition described in Table 1, and then pulverize them under the same conditions as in Example 1. After granulating the pulverized slurry, fill the resulting mixed powder into a mold and press it at a pressure of 785 kfg / cm². 2 Holding time: 1 minute for uniaxial forming, then pressing pressure: 1795 kgf / cm 2 CIP molding was performed with a holding time of 1 minute to produce a molded body. Then, the molded body was subjected to atmospheric sintering at a maximum sintering temperature of 1400°C and a holding time of 10 hours to produce a sintered body. The physical properties of the sintered body obtained in Comparative Example 2 were measured, and the results showed a low relative density and an average crystal grain size of 2.36 μm, which were not the expected results.

[0079] Industrial availability According to this disclosure, a sintered body and sputtering target containing indium, zinc, and oxygen, with a small average crystal grain size and high density, can be provided. Furthermore, according to this disclosure, it is expected that particles during sputtering can be suppressed, thus potentially improving product yield. Improved product yield contributes to a stable supply of products and reduces the loss of metal raw materials, which are finite resources. Therefore, this disclosure may contribute to UN-led Sustainable Development Goals (SDGs) Goal 9, “Building resilient infrastructure, promoting inclusive and sustainable industrialization and pursuing expanded technological innovation,” and Goal 12, “Ensuring sustainable consumption and production patterns.” The sintered body and sputtering target of this 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, having an average crystal grain size of less than 2 μm and a relative density of more than 99%.

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

3. The sintered body according to claim 1 or 2, wherein, Its Vickers hardness is above 500 HV.

4. The sintered body according to any one of claims 1 to 3, wherein, The volume resistivity is below 5 mΩ·cm.

5. The sintered body according to any one of claims 1 to 4, characterized in that, Saturation C * It is below 2.

0.

6. The sintered body according to any one of claims 1 to 5, wherein, The Zn content, converted from ZnO, is 1% by mass or more and 37% by mass or less.

7. A sputtering target comprising a sintered body as described in any one of claims 1 to 6.

8. The sputtering target according to claim 7, wherein, The area of ​​the sputtering surface is 44 cm². 2 above.

9. A method for manufacturing a sintered body, wherein, In2O3 powder and ZnO powder are mixed, and the resulting mixed powder is filled into a sintering apparatus. Metal components constituting a metal oxide with a standard generating Gibbs energy higher than that of the mixed powder are placed around the mixed powder in the sintering apparatus, and then hot-pressed.

10. The method for manufacturing a sintered body according to claim 9, wherein, Under vacuum or inert gas atmosphere, at a maximum sintering temperature of 1100–1300℃ and a pressing pressure of 150 kgf / cm². 2 The mixed powder is hot-pressed under the above conditions.

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