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

Abstract

The present disclosure addresses the problem of providing: a sintered body and a sputtering target containing indium, zinc, and oxygen and having exceptional thermal shock resistance; and a method for producing a sintered body. Provided is an IZO sintered body containing indium, zinc, and oxygen, wherein: the sintered body includes an In2O3 phase and a Zn4In2O7 phase; and the sintered body is such that I1 / I2 is 1.0 or higher, where I1 is the X-ray diffraction peak intensity at 34.1° ≤ 2θ ≤ 35.1° of the Zn4In2O7 phase, and I2 is the sum of X-ray diffraction peak intensities at 34.1° ≤ 2θ ≤ 35.1° of a Zn3In2O6 phase or a Zn5In2O8 phase.

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

[0003] As a method for forming an IZO film, a sputtering method using an IZO sputtering target manufactured from an IZO sintered body is widely used. ２ O ３ and Zn ｋ In ２ O ｋ＋３ (k=one or more of 3, 4, and 5), the target has a relative density of 98.4% or more, the number of micropores of 50 to 300 nm present in the target is 10 or less, and the atomic ratio of Zn to In, Zn / (In+Zn), is in the range of 0.1 to 0.2.

[0004] Patent No. 6078189

[0005] In an IZO sputtering target containing indium, zinc, and oxygen, a problem has arisen in that the sputtering target breaks or cracks due to thermal shock during sputtering. In view of the above problem, an object of the present disclosure is to provide a sintered body and a sputtering target containing indium, zinc, and oxygen and having excellent thermal shock resistance, as well as a method for manufacturing the sintered body.

[0006] The gist of the present disclosure is as follows: [1] An IZO sintered body containing indium, zinc, and oxygen, comprising In ２ O ３ phase and Zn ４ In ２ O ７ phase, Zn ４ In ２ O ７ The X-ray diffraction peak intensity of the Zn phase at 34.1°≦2θ≦35.1° is designated as I1. ３ In ２ O ６ phase and Zn ５ In ２ O ８ [1] A sintered body having an I1 / I2 ratio of 1.0 or more, where I2 is the sum of the X-ray diffraction peak intensities of the phase at 34.1°≦2θ≦35.1°. [2] The sintered body according to [1], having an average crystal grain size of 2 μm or less. [3] The sintered body according to [1] or [2], having a relative density of 90% or more and less than 99%. [4] The sintered body according to any one of [1] to [3], having a reduction rate of bending strength of 40% or less, calculated from the following formula: The rate of decrease in bending strength (%) = {(Bend rupture strength before thermal shock test) - (Bend rupture strength after thermal shock test)} / (Bend rupture strength before thermal shock test) x 100. The thermal shock test is performed by heating the sintered body in air at a temperature increase rate of 5°C / min, a holding temperature of 200°C, and a holding time of 30 minutes, and then rapidly cooling the sintered body immediately after heating by gravity dropping it from a height of 30 cm above the water surface into a water tank 30 cm deep (water temperature 20°C ± 3°C). [5] The sintered body according to any one of [1] to [4], having a volume resistivity of 10 mΩ cm or less. [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, calculated as ZnO. [7] A sputtering target produced from the sintered body according to any one of [1] to [6]. [8] In ２ O ３ The powder and ZnO powder are mixed, and the resulting mixed powder is calcined at 1200°C or higher but lower than 1258°C. The calcined powder is then pressed under vacuum or an inert gas atmosphere at 1100°C or higher but lower than 1250°C and a pressure of 150 kgf / cm. ２ A method for producing a sintered body by pressure sintering under the above conditions.

[0007] According to the present disclosure, it is possible to provide a sintered body and a sputtering target containing indium, zinc, and oxygen and having excellent thermal shock resistance, as well as a method for producing the sintered body.

[0008] 1 shows an X-ray diffraction pattern (10°≦2θ≦80°) of the sintered body of Example 2. FIG. 2 shows an X-ray diffraction pattern (34.1°≦2θ≦35.1°) of the sintered body of Example 2.

[0009] 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.

[0010] 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 is called 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 can be used as transparent conductive films or oxide semiconductors.

[0011] An IZO thin film can usually be formed by sputtering. A sputtering target made from an IZO sintered body (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 with approximately the same composition as the sputtering target.

[0012] The sintered body according to this embodiment is made of In ２ O ３ phase and Zn ４ In ２ O ７ phase, Zn ４ In ２ O ７ The X-ray diffraction peak intensity of the Zn phase at 34.1°≦2θ≦35.1° is designated as I1. ３ In ２ O ６ phase and Zn５ In ２ O ８ When the sum of the X-ray diffraction peak intensities of the indium and zinc composite oxide phase at 34.1°≦2θ≦35.1° is defined as I2, the sintered body has an I1 / I2 ratio of 1.0 or more. ４ In ２ O ７ The indium and zinc composite oxide contains Zn. ４ In ２ O ７ In addition to the phase, Zn ３ In ２ O ６ Phase, Zn ５ In ２ O ８ Among these complex oxide phases, Zn ４ In ２ O ７ By making the phase the main phase, the thermal shock resistance of the IZO sputtering target can be improved. A sputtering target with excellent thermal shock resistance can suppress cracks and fractures during sputtering.

[0013] The sintered body according to this embodiment preferably has an average crystal grain size of 2 μm or less. It is more preferably 1.5 μm or less, and even more preferably 1 μm or less. If the average crystal grain size of the sintered body is coarse, the flexural strength decreases, and cracks and fractures may occur during sputtering. Cracks and fractures cause the generation of particles and nodules during sputtering. Therefore, to prevent cracks and fractures, it is preferable to refine the structure of the IZO sintered body (IZO sputtering target). The crystal grain size depends on the particle size of the powder used as the sintering raw material and various sintering conditions, and therefore these must be appropriately controlled.

[0014] Because IZO sintered bodies require a fine crystalline structure, sintering at low temperatures, which can suppress grain growth, is preferable. However, low-temperature sintering makes it difficult to obtain high-density sintered bodies. However, the manufacturing method described below in the present disclosure makes it possible to obtain high-density sintered bodies while suppressing grain growth. A sputtering target made of a high-density IZO sintered body can suppress particle generation during sputtering. If the relative density is too low, the flexural strength of the sintered body decreases, making it unsuitable as a sintered body for producing a sputtering target. On the other hand, if the relative density of the sintered body is too high, impact thermal stress is more easily transmitted, resulting in a large decrease in flexural strength due to heat treatment. Therefore, the sintered body according to this embodiment preferably has a relative density of 90% or more but less than 99%. A more preferred relative density is 92% or more, particularly preferably 95% or more, and a more preferred relative density is 98% or less, particularly preferably 97% or less.

[0015] In the present disclosure, thermal shock resistance is evaluated based on the rate of decrease in the flexural strength of the sintered body before and after the thermal shock test. The lower the rate of decrease in flexural strength after the thermal shock test, the better the thermal shock resistance can be determined. The rate of decrease in flexural strength is calculated according to the following procedure: (1) Measure the flexural strength of the sintered body before the thermal shock test. (2) Heat the sintered body in air at a temperature increase rate of 5°C / min, a holding temperature of 200°C, and a holding time of 30 minutes. (3) Drop the sintered body immediately after heating from a height of 30 cm above the water surface into a water tank 30 cm deep (water temperature 20°C ± 3°C) and rapidly cool it. (4) Measure the flexural strength of the sintered body after the thermal shock test according to steps (2) and (3). (5) Calculate the rate of decrease in flexural strength from the flexural strengths measured in steps (1) and (4) using the following formula: Reduction rate of flexural strength (%) = {(flexural strength before thermal shock test) - (flexural strength after thermal shock test)} / (flexural strength before thermal shock test) × 100. The reduction rate of flexural strength varies greatly depending on the composition of the sintered body. That is, the reduction rate of flexural strength tends to decrease as the Zn content increases (as the In content decreases).

[0016] The sintered body according to this embodiment preferably has a volume resistivity of 10 mΩ·cm or less. If the volume resistivity is high, arcing occurs during sputtering, which can cause particles, so it is preferable that the volume 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 6 mΩ·cm or less, and more preferably 3 mΩ·cm or less.

[0017] 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 is more preferably 2.5% by mass or more, calculated as ZnO, and particularly preferably 7.0% by mass or more. The upper limit of the Zn content is preferably 25% by mass or less, calculated as ZnO, and particularly preferably 15% by mass or less.

[0018] 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.

[0019] A method for manufacturing a sintered body and a sputtering target according to this embodiment will now be described. However, the manufacturing conditions and the like below 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 manufacturing steps and processing operations will be omitted to avoid unnecessarily obscuring the disclosed manufacturing method.

[0020] (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 d ５０ :0.5-3.0μm, specific surface area: 4.0-10m ２ The ZnO powder preferably has a median diameter d ５０ The particle size is preferably 0.1 to 2.0 μm. The raw material powder preferably has a purity of 99.9% by mass or more.

[0021] (2. Mixing step) The 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 provides a good dispersion state of additives. The median diameter d after pulverization is ５０ is preferably 0.1 to 1.0 μm.

[0022] (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.

[0023] (4. Calcination Step) Next, the mixed powder is calcined at a temperature of 1200°C or higher and lower than 1258°C. By performing the calcination, Zn ４ In ２ O ７ If the calcination temperature is 1258°C or higher, the sintered body will have the desired crystalline phase, Zn. ４ In ２ O ７ phase, but Zn ３ In ２ O ６If the calcination temperature is too high, the sintering will be too hard, which may make the crushing process in the subsequent step complicated. ４ In ２ O ７ Phase and non-target Zn ５ In ２ O ８ A phase is formed. The calcination time is preferably 1 hour or more and 10 hours or less. If the calcination time is too short, the target crystalline phase will not be formed, while if the calcination time is too long, the calcination will be too hard, which may make the subsequent crushing process complicated. There are no particular restrictions on the temperature increase rate or temperature decrease rate. For example, the temperature can be increased to the target temperature at a rate of 1°C / min or more and 10°C / min or less, and after the temperature is maintained, the temperature can be decreased by furnace cooling.

[0024] (5. Crushing step: optional) The calcined powder obtained by the above calcination is preferably crushed using a sieve. If the mesh size of the sieve is 500 μm or less, the densification can be removed. The smaller the mesh size, the more the densification can be removed, and by setting the mesh size to 250 μm or even 150 μm, the densification can be further removed. On the other hand, if the mesh size is too large, the crushing operation in the next step may become complicated.

[0025] (6. Pulverization step: optional) Next, pulverization can be carried out as necessary. 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. In order to obtain uniform and fine crystal particles, a wet bead mill mixing method is preferred, which has high efficiency in crushing agglomerates in a short time and also provides a good dispersion state of additives. The median diameter d after pulverization ５０ is preferably 0.1 to 1.0 μm.

[0026] (7. Sintering Process) Next, the calcined 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 flexural strength. Furthermore, the volume resistivity increases, generating particles during sputtering, making stable sputtering difficult. Stabilizing sputtering is particularly important when sputtering targets become larger and uniform film deposition is attempted using high-power sputtering.

[0027] (7-1. Sintering Method) In the manufacturing method of the present disclosure, pressure sintering is performed from the viewpoint of increasing the relative density at a relatively low temperature. For pressure sintering, hot press (HP) sintering or SPS (spark plasma sintering) can be used. The atmosphere during sintering can be a vacuum or an inert gas atmosphere, but sintering in an inert gas atmosphere is preferable to a vacuum. In addition, when sintering in an inert gas atmosphere without pressure (atmospheric pressure), In ２ O ３ However, this may reduce the Zn content, hindering the increase in density of the sintered body and contaminating the inside of the device. 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. The sintering temperature is preferably 1100°C or higher and 1250°C or lower. If the sintering temperature is lower than 1100°C, the density of the sintered body will not increase sufficiently, while if the sintering temperature is higher than 1250°C, the Zn content, which is the target crystal phase, will not increase. ４ In ２ O ７ phase, but Zn ３ In ２ O ６ There is a problem with phase emergence.

[0028] (7-2. Pressing pressure) The pressing pressure during pressure sintering is 150 kgf / cm ２ 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 500 kgf / cm2 in view of the strength of the members used in pressure sintering. ２ It is preferable to have the following:

[0029] (7-3. Sintering Holding Time) The holding time at the maximum sintering temperature is preferably 3 hours or more and 10 hours or less. 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.

[0030] (7-4. HIP Treatment: Optional) 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 1250°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.

[0031] (8. Finishing) The sintered body obtained through the above sintering step can be processed into a desired shape using a processing machine such as a surface grinder, a cylindrical grinder, or a machining machine, and the surface can be polished to form a sputtering target. 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, if necessary.

[0032] 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.

[0033] The evaluation methods used in the examples and comparative examples are as follows. Sputtering targets are produced by subjecting sintered bodies to processing such as grinding and polishing, and therefore the properties of the sintered bodies can be considered equivalent to the properties of sputtering targets. Furthermore, in this disclosure, various evaluations are performed on samples representative of sintered bodies, and if the various physical properties of the representative samples fall within the scope of this disclosure, the sintered bodies are encompassed by the present invention. In other words, measuring a unique, exceptional, or partial sample that is not representative of a sintered body does not mean that the sample falls outside the scope of this disclosure.

[0034] (Composition Analysis) The composition of the sintered body was analyzed using the following device: Device: SPS3500DD manufactured by SII Method: ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy)

[0035] (Analysis of Crystalline Phase) A sample (15 mm x 15 mm x 10 mm) was cut out from the sintered body, and the surface of the cut out sample (the surface corresponding to the sputtered surface) was mirror-polished using a slurry abrasive (COMPOL120, manufactured by Fujimi Incorporated). Then, the crystal phase of the sintered body was analyzed using the following equipment. Principle: X-ray diffraction method Equipment: Ultima IV manufactured by Rigaku Corporation Tube: Cu-Kα ray Tube voltage: 40 kV Current: 30 mA Measurement method: 2θ-θ reflection method Scan speed: 40° / min Sampling interval: 0.01° Measurement range (2θ): 10° to 120° Divergence slit: 1° Divergence vertical limiting slit: 10 mm Scattering slit: 8 mm Receiving slit: open state Goniometer: horizontal type for sample Sample measurement location: sputtered cross-section side

[0036] Zn ４ In ２ O ７ The X-ray diffraction peak intensity at 34.1°≦2θ≦35.1° attributed to the Zn phase is designated as I1. ３ In ２ O ６ phase and Zn ５ In ２ O ８The sum of the X-ray diffraction peak intensities of the Zn phase at 34.1°≦2θ≦35.1° was taken as I2, and I1 / I2 was calculated. ５ In ２ O ８ The X-ray diffraction peak intensity attributable to the Zn phase (ICDD card number, 01-089-8974) was taken as the maximum peak intensity at 34.74°±0.05°. ３ In ２ O ６ The phase (ICDD card number, 00-020-1439) was determined as the maximum peak intensity at 34.23°±0.05°. ４ In ２ O ７ The phase (ICDD card number, 01-077-8496) was taken as the maximum peak intensity at 34.97°±0.05°.

[0037] (Regarding relative density) The relative density was calculated using the following formula: Relative density (%) = Archimedes density / Calculated density × 100 Archimedes density: A sample (15 mm × 15 mm × 10 mm) 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. Note that when the relative density is 94% or less, it is preferable to calculate using the dimensional density. Calculated density: The oxide mass ratio (mass%) of In 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 through a component analysis of the sintered body. ２ O ３ The calculated density was calculated using the following theoretical density of ZnO: Calculated density (g / cm 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) Theoretical density: d1: 7.18 g / cm３ (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 (15 mm x 15 mm x 10 mm) was cut from the sintered body, the cut sample surface was polished, and a microstructure photograph of the mirror-polished sample surface (a cross section perpendicular to the surface corresponding to the sputtered surface) was taken using a scanning electron microscope (SEM) at a magnification of 5000 times in six fields. Next, on the photographed image, three or fewer lines (referred to as lines 1, 2, and 3) were drawn so that the number of crystal grains crossed by each line was 10 or more, and the length of each line and the number of crystal grains crossed by each line were determined. At this time, crystal grains whose ends were inside the line 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, for each of the six fields of view, the crystal grain size was calculated 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 crossed by each line in 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] (Volume Resistivity) The surface of the sintered body 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)

[0040] (Regarding flexural strength) A sample (40 mm x 4 mm x 3 mm) was cut out from the sintered body, the surface of the cut sample was polished with an abrasive (grit #400), and the flexural strength of the polished surface was measured in accordance with JIS R1601: 2008. Test method: Room temperature flexural strength test method for fine ceramics Equipment: Tension / compression testing machine (SV-201NA-50SL type) Test type: Three-point flexural strength measurement Test temperature: 5 to 35°C Distance between external supports: 30 mm Crosshead speed: 0.5 mm / min Load range: Range A 500 N At least 10 tests were conducted, and the average value was calculated.

[0041] (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 1210°C. ５０ The powder was then crushed in a wet bead mill to a particle size of 0.68 μm. After crushing, the resulting powder was filled into a carbon die and sintered in an argon atmosphere at a maximum sintering temperature of 1150°C and a pressing pressure of 300 kgf / cm. ２ A sintered body (diameter: 210 mm) was produced by hot pressing (HP) under the conditions of 0.15 to 1.05 MPa, and 0.25 to 1.05 MPa for 3 hours. The physical properties of the sintered body obtained in Example 1 were measured, and the Zn content was found to be 10.7 wt % in terms of ZnO, and the main crystalline phase was In. ２ O ３ phase and Zn ４ In ２ O ７ The X-ray diffraction peak intensity ratio I1 / I2 was 1.29, and the Zn phase ４ In ２ O ７ The sintered body was then subjected to the thermal shock test described above, and the flexural strength was measured. The flexural strength after the heat treatment was 144 MPa, and the reduction rate of the flexural strength was 31%, demonstrating good thermal shock resistance.

[0042]

[0043] Example 2 In Example 2, the composition of the sintered body was adjusted to be different from that of Example 1, and the sintering was carried out in an argon atmosphere at a maximum sintering temperature of 1150°C and a press pressure of 250 kgf / cm. ２ A sintered body (diameter: 160 mm) was produced by hot pressing (HP) under the conditions of 0.15 to 1.5 hours, and a holding time of 3 hours. The physical properties of the sintered body obtained in Example 2 were measured, and it was found that the Zn content was 37 wt % in terms of ZnO, and the main crystalline phase was In. ２ O ３ phase and Zn ４ In ２ O ７ The X-ray diffraction peak intensity ratio I1 / I2 was 1.93, and the Zn phase ４ In ２ O ７ The phase was the main phase. For reference, the X-ray diffraction patterns of Example 2 are shown in Figures 1 and 2. The flexural strength was 192 MPa, the average crystal grain size was 1.17 µm, the relative density was 97.7%, and the volume resistivity was 0.86. Next, a thermal shock test was performed on the sintered body, and the flexural strength after the thermal shock test was measured. As a result, the flexural strength after the thermal shock test was 165 MPa, and the reduction rate of the flexural strength was 14%, indicating good thermal shock resistance.

[0044] Comparative Example 1 In Comparative Example 1, the calcination temperature was adjusted to 1100°C, and the maximum sintering temperature was 1150°C under an argon atmosphere, and the pressing pressure was 300 kgf / cm. ２ A sintered body (diameter: 210 mm) was produced by hot pressing (HP) sintering under the conditions of 1000 kJ / cm2, 1000 kJ / cm2, and 1000 kJ / cm2 for 6 hours. The physical properties of the sintered body obtained in Comparative Example 1 were measured, and the Zn content was 37 wt % in terms of ZnO, and the main crystalline phase was In. ２ O ３ phase and Zn ５ In ２ O ８ The X-ray diffraction peak intensity ratio I1 / I2 was 0.73, and the Zn phase ５ In ２ O ８ The sintered body was found to have a flexural strength of 223 MPa. The sintered body was then subjected to a thermal shock test to measure its flexural strength after the test. The flexural strength after the test was 106 MPa, a reduction rate of 52%, and poor thermal shock resistance.

[0045] Comparative Example 2 In Comparative Example 2, the calcination temperature was adjusted to 1100°C, and the maximum sintering temperature was 1200°C under an argon atmosphere, and the pressing pressure was 250 kgf / cm. ２ A sintered body (diameter: 160 mm) was produced by hot pressing (HP) sintering under the conditions of 0.15 to 1.5 hours, and a holding time of 3 hours. The physical properties of the sintered body obtained in Comparative Example 1 were measured, and the Zn content was found to be 37 wt % in terms of ZnO, and the main crystalline phase was In. ２ O ３ phase and Zn ５ In ２ O ８ The X-ray diffraction peak intensity ratio I1 / I2 was 0.68, and the Zn ５ In ２ O ８ The sintered body was found to have a flexural strength of 185 MPa. Next, a thermal shock test was conducted on the sintered body, and the flexural strength after the thermal shock test was measured. As a result, the flexural strength after the thermal shock test was 101 MPa, and the reduction rate of the flexural strength was 45%, indicating that the thermal shock resistance was poor.

[0046] This disclosure is expected to suppress cracks and fractures in sputtering targets, potentially improving product yields. Improving product yields leads to a stable supply of products and reduced loss of metal raw materials, which are limited resources. Therefore, this disclosure may contribute to the achievement of Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster technological innovation," and Goal 12, "Ensure sustainable consumption and production patterns."

[0047] According to the present disclosure, it is possible to provide an IZO sintered body and an IZO sputtering target that contain indium, zinc, and oxygen and have high thermal shock resistance. The sintered body and the sputtering target according to the present disclosure are useful for forming an IZO thin film as a transparent conductive film or an oxide semiconductor film.

Claims

1. An IZO sintered body containing indium, zinc, and oxygen, ２ O ３ phase and Zn ４ In ２ O ７ phase, Zn ４ In ２ O ７ The X-ray diffraction peak intensity of the Zn phase at 34.1°≦2θ≦35.1° is designated as I1. ３ In ２ O ６、 phase or Zn ５ In ２ O ８ A sintered body having an I1 / I2 ratio of 1.0 or more, where I2 is the sum of the X-ray diffraction peak intensities of the phase at 34.1°≦2θ≦35.1°.

2. The sintered body according to claim 1, wherein the average crystal grain size is 2 μm or less.

3. The sintered body according to claim 1, having a relative density of 90% or more and less than 99%.

4. The sintered body according to claim 1, wherein the rate of decrease in flexural strength calculated by the following formula is 40% or less: Rate of decrease in flexural strength (%) = {(flexural strength before thermal shock test) - (flexural strength after thermal shock test)} / (flexural strength before thermal shock test) x 100, where the thermal shock test is carried out by heating the sintered body in air at a heating rate of 5°C / min, at a holding temperature of 200°C, and for a holding time of 30 minutes, and then dropping the sintered body immediately after heating into a water tank 30 cm deep (water temperature 20°C ± 3°C) from a height of 30 cm above the water surface to rapidly cool it.

5. The sintered body according to claim 1, having a volume resistivity of 10 mΩ·cm or less.

6. The sintered body according to claim 1, 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. In ２ O ３ The powder and ZnO powder are mixed, and the resulting mixed powder is calcined at 1200°C or higher but lower than 1258°C. The calcined powder is then pressed under vacuum or an inert gas atmosphere at 1100°C or higher but lower than 1250°C and a pressure of 150 kgf / cm. ２ A method for producing a sintered body by pressure sintering under the above conditions.

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