JP2015214437A - Oxide sintered body and sputtering target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an In-Sn-Zn oxide-based sintered body which is suppressed non-sputtering during sputtering and reduced in cracking.SOLUTION: An oxide sintered body contains In, Sn and Zn, includes at least one of a HfOphase and a ZrOphase and has an average particle size of the HfOphase and the ZrOphase of 10 μm or smaller.

Description

  The present invention relates to an oxide sintered body and a sputtering target comprising the same.

An oxide film formed using a sputtering target made of an oxide sintered body is used for a transparent electrode such as a liquid crystal display device or an organic electroluminescence display device, a semiconductor layer of a thin film transistor (TFT), or the like.
In the oxide sintered sputtering target, when the resistance value is low, nodule is likely to be generated due to the difference in resistance between the high-deposition redeposition film (reattachment film) and the low-resistance target. It tends to occur. If arcing such as fireball discharge occurs, the target may break. When sputtering discharge is performed with a cracked target, a uniform oxide film cannot be formed due to arcing generated at the cracked portion, which causes a decrease in yield.

In particular, since the In—Sn—Zn oxide-based sintered body is easy to be fired, the particle diameter of the crystal phase tends to be large, and the resistance value is small. In the case where nodules are generated, if the crystal phase is large, cracks progress at a stretch, and therefore, cracks and cracks are likely to occur in the target.
For the In-Sn-Zn oxide-based sintered body, for example, Patent Documents 1 to 4 can be referred to.

Japanese Patent No. 4846726 Patent No. 4960244 Patent No. 5188182 International Publication WO2012 / 067036

  An object of the present invention is to provide an In—Sn—Zn oxide-based sintered body that suppresses arcing during sputtering and has few cracks.

The present inventors have found that the grain growth of the crystal phase can be suppressed by forming HfO ₂ or ZrO ₂ in the In—Sn—Zn oxide-based sintered body, and completed the present invention. It has also been found that excessive reduction in resistance of the sintered body can be suppressed.
According to the present invention, the following oxide sintered bodies and the like are provided.
1. Including each element of In, Sn and Zn,
Having at least one of HfO ₂ phase or ZrO ₂ phase,
The oxide sintered body, wherein the HfO ₂ phase and the ZrO ₂ phase have an average particle size of 10 μm or less.
2. 2. The oxide sintered body according to 1, wherein the average particle diameter of all crystal phases is 10 μm or less.
3. _3. The oxide sintered body according to 1 or 2, wherein at least one element of In or Sn is dissolved in the HfO ₂ phase and the ZrO ₂ phase.
4). Further, at least one of phases selected from an In ₂ O ₃ phase, a Zn ₂ SnO ₄ phase, a ZnSnO ₃ phase, and an In ₂ O _3. (ZnO) _m (m is an integer of 1 or more) phase. The oxide sintered body according to any one of 1 to 3, wherein the oxide sintered body is included.
5. 5. The oxide sintered body according to any one of 1 to 4, wherein the relative density is 95% or more.
6). 6. The oxide sintered body according to any one of 1 to 5, wherein the resistance value is 2 mΩ or more and 100 mΩcm or less.
7). The oxide sintered body according to any one of 1 to 6, wherein an atomic ratio of In, Sn, Zn, Hf, and Zr satisfies the following formulas (1) to (4):
0.20 ≦ In / (In + Sn + Zn + X) ≦ 0.70 (1)
0.01 ≦ Sn / (In + Sn + Zn + X) ≦ 0.40 (2)
0.01 ≦ Zn / (In + Sn + Zn + X) ≦ 0.60 (3)
0.002 ≦ X / (In + Sn + Zn + X) ≦ 0.25 (4)
(In the formula, X represents at least one element of Hf or Zr.)
8). 8. A sputtering target obtained by processing the oxide sintered body according to any one of 1 to 7 above.
9. 9. An oxide thin film formed using the sputtering target according to 8 above.
10. 10. The oxide thin film according to 9, which is an amorphous film.
11. 11. A thin film transistor comprising the oxide thin film according to 9 or 10 as a channel layer.

  ADVANTAGE OF THE INVENTION According to this invention, the arcing at the time of sputtering can be suppressed and the In-Sn-Zn oxide type sintered compact with few cracks can be provided. As a result, a target capable of stable sputtering can be provided.

2 is an X-ray diffraction pattern of an oxide sintered body produced in Example 1. FIG. 2 is a SEM photograph of a cross section of an oxide sintered body produced in Example 1. It is the figure which showed the distribution state of Zr atom in the visual field of the SEM photograph of FIG. 2 by SEM-EDS. It is an EDS spectrum of the phase of the arrow part shown in the SEM photograph of FIG. 7 is a SEM photograph of a cross section of an oxide sintered body produced in Example 6. It is the figure which showed the distribution state of the Hf atom in the visual field of the SEM photograph of FIG. 5 by SEM-EDS. It is an EDS spectrum of the phase of the arrow part shown in the SEM photograph of FIG.

The oxide sintered body of the present invention contains each element of In, Sn, and Zn, and has at least one of an HfO ₂ phase or a ZrO ₂ phase. Then, wherein the average particle size of the HfO ₂ phase and ZrO ₂ phase is 10μm or less.
The HfO ₂ phase and the ZrO ₂ phase are dispersed in the sintered body with an average particle size of 10 μm or less, thereby suppressing grain growth of each phase (pinning effect). Thereby, the particle diameter of each phase formed in a sintered compact can be made small. As a result, the strength of the sintered body can be increased. Moreover, since generation | occurrence | production of a long crack can be suppressed, the crack of a target can be suppressed.

It can be confirmed by an X-ray diffraction method that the oxide sintered body has an HfO ₂ phase or a ZrO ₂ phase.
A part of Hf or Zr may be dissolved in the homologous phase or other crystal phase or may be another compound.

  The elements contained in the phase (particles) present in the oxide sintered body are specified by a scanning electron microscope and an energy dispersive X-ray spectrometer (SEM-EDS). Specifically, the position and shape of the particles are confirmed by observing a mirror-polished sintered body with an SEM, and the elements contained in the particles are identified by EDS for each particle.

The average particle size of the HfO ₂ phase and the ZrO ₂ phase is 10 μm or less. It is preferably 5 μm or less, and particularly preferably 3 μm or less. If the average particle size is 10 μm or less, it is easy to obtain the effect of suppressing the particle size in the sintered body. As a result, even if cracks occur between the particles, the length is short, so that the sintered body can be prevented from cracking.

  In the present invention, the average particle diameter of all crystal phases formed in the sintered body is preferably 10 μm or less. Furthermore, it is preferable that it is 5 micrometers or less, and it is especially preferable that it is 3 micrometers or less. If the average particle diameter is 10 μm or less, even if cracks occur between the particles, the length is short, so that cracking of the sintered body can be suppressed.

  The average particle diameter of each phase is measured by observing a mirror-polished sintered body with a scanning electron microscope (SEM). When the shape of the surface of the sintered body is circular, the square inscribed in the circle is divided into 16 equal areas, and when the surface shape of the sintered body is square, the surface is divided into 16 equal areas. Each of 16 samples is prepared and measured. Details of the measurement are given in the examples.

  In addition, although the method of adding an additive to oxide sintered compact is known, in order to reduce the crack in a sintered compact like this invention, the grain boundary in a sintered compact is controlled, discharge stability There was no idea of improving sex.

In the present invention, at least one element of In or Sn may be dissolved in the HfO ₂ phase and / or the ZrO ₂ phase. When In is dissolved, the resistance value is appropriately reduced, and therefore arcing due to segregation of the HfO ₂ phase and the ZrO ₂ phase can be suppressed.
It can be confirmed by SEM-EDS that In or Sn is dissolved.

In the oxide sintered body of the present invention, in addition to the above phases, an In ₂ O ₃ phase, a Zn ₂ SnO ₄ phase, a ZnSnO ₃ phase, and In ₂ O _3. (ZnO) _m (m is 1 or more) It may be an integer.) It may contain at least one of the phases selected from the phases. When the atomic ratio of In is high, an In ₂ O ₃ phase is included in a region where In is large. In this case, a part of Hf or Zr may be dissolved in the In ₂ O ₃ phase. When dissolved, the resistance value of the In ₂ O ₃ phase decreases and the target resistance value tends to be an appropriate value, so that more stable sputtering discharge is possible.
It can be confirmed by an X-ray diffraction method that the sintered body contains each of the above phases. Specifically, it can be confirmed by comparing the X-ray diffraction result with an ICDD (International Center for Diffraction Data) card. The In ₂ O ₃ phase is, for example, an ICDD card No. 6-416 pattern is shown. The Zn ₂ SnO ₄ phase is the ICDD card no. The pattern of 24-1740 is shown. The ZnSnO ₃ phase is ICDD card no. 77-4192 is shown. In ₂ O _3. (ZnO) _m is, for example, in the case of m = 2, 3, 4, 5, 8, respectively, the ICDD card No. 20-1442, no. 20-1439, no. 20-1438, no. 20-1440, no. 1441 patterns are shown.

The HfO ₂ phase and the ZrO ₂ phase are preferably monoclinic. Thereby, the dispersibility in a sintered compact can be raised.
The monoclinic system can be confirmed by an X-ray diffraction method.

The relative density of the oxide sintered body is preferably 95% or more, more preferably 97% or more, and particularly preferably 98% or more. If it is 95% or more, the target is difficult to break and abnormal discharge can be further suppressed.
The relative density is a percentage obtained by dividing the actual density measured by the Archimedes method by the theoretical density calculated from the arithmetic average of the true density of the raw material.

The resistance value of the oxide sintered body of the present invention is preferably 2 mΩcm or more and 100 mΩcm or less. If it is this range, generation | occurrence | production of the nodule at the time of sputtering can be suppressed more, and as a result, arcing can also be suppressed. The resistance value is preferably 50 mΩcm or less, more preferably 30 mΩcm or less, and particularly preferably 20 mΩcm or less. If it is 50 mΩcm or less, an arcing abnormal discharge is less likely to occur, which is preferable. When it is 30 mΩcm or less, normal DC sputtering is possible. When it is 20 mΩcm or less, weak magnetic field magnetron sputtering is possible.
The resistance value can be measured by a low resistivity meter “Lorestar EP” (based on JIS K 7194) manufactured by Mitsubishi Chemical Corporation. Details of the measurement are given in the examples.

Regarding the composition of the oxide sintered body of the present invention, the atomic ratio of In, Sn, Zn, Hf, and / or Zr (hereinafter, Hf and / or Zr may be collectively referred to as element X) is represented by the following formula (1). It is preferable to satisfy (4).
0.20 ≦ In / (In + Sn + Zn + X) ≦ 0.70 (1)
0.01 ≦ Sn / (In + Sn + Zn + X) ≦ 0.40 (2)
0.01 ≦ Zn / (In + Sn + Zn + X) ≦ 0.60 (3)
0.002 ≦ X / (In + Sn + Zn + X) ≦ 0.25 (4)

In the formula, X represents at least one element of Hf or Zr. When the oxide sintered body contains only one element, X represents Hf or Zr, and when both contain both, X means the sum of Hf and Zr.
By satisfying the above atomic ratio, a transistor with high mobility can be obtained by using the obtained oxide thin film for a thin film transistor.

In the present invention, it is more preferable that the atomic ratio of the oxide sintered body satisfies the following relationship.
0.30 ≦ In / (In + Sn + Zn + X) ≦ 0.65
0.05 ≦ Sn / (In + Sn + Zn + X) ≦ 0.35
0.10 ≦ Zn / (In + Sn + Zn + X) ≦ 0.55
0.025 ≦ X / (In + Sn + Zn + X) ≦ 0.20

In the present invention, it is more preferable that the atomic ratio of the oxide sintered body satisfies the following relationship.
0.33 ≦ In / (In + Sn + Zn + X) ≦ 0.60
0.10 ≦ Sn / (In + Sn + Zn + X) ≦ 0.30
0.20 ≦ Zn / (In + Sn + Zn + X) ≦ 0.50
0.003 ≦ X / (In + Sn + Zn + X) ≦ 0.15

The atomic ratio of each metal element in the oxide sintered body can be controlled by the blending amount of the raw materials. Further, the atomic ratio of each element can be obtained by quantitative analysis of the contained elements using an inductively coupled plasma emission spectrometer (ICP-AES).
Specifically, in the analysis using ICP-AES, when a solution sample obtained by dissolving a powder obtained by pulverizing an oxide sintered body to 10 μm or less in an acid or the like is atomized with a nebulizer and introduced into argon plasma, These elements are excited by absorbing thermal energy, and the orbital electrons move from the ground state to the high energy level orbit. These orbital electrons move to a lower energy level orbit in about 10 ⁻⁷ to 10 ⁻⁸ seconds. At this time, the energy difference is emitted as light to emit light. Since this light shows a wavelength (spectral line) unique to the element, the presence of the element can be confirmed by the presence or absence of the spectral line (qualitative analysis).

In addition, since the magnitude (luminescence intensity) of each spectral line is proportional to the number of elements in the sample, the sample concentration can be obtained by comparing with a standard solution having a known concentration (quantitative analysis).
After identifying the elements contained in the qualitative analysis, the content is obtained by quantitative analysis, and the atomic ratio of each element is obtained from the result.

The oxide sintered body of the present invention can be produced, for example, by firing a raw material powder containing each metal element. Hereinafter, the manufacturing process will be described.
(1) Compounding Process The compounding process of raw materials is an essential process for mixing the metal element compound contained in the oxide of the present invention.
As the raw material, powders such as indium compound powder, tin compound powder, zinc compound powder, and element X compound powder are used. Examples of the indium compound include indium oxide and indium hydroxide. Examples of the tin compound include tin dioxide, stannous oxide, and tin hydroxide. Examples of the zinc compound include zinc oxide and zinc hydroxide. As each compound, an oxide is preferable from the viewpoint of easiness of firing and the difficulty of leaving a by-product.
The purity of the raw material is usually 2N (99% by mass) or more, preferably 3N (99.9% by mass) or more, particularly preferably 4N (99.99% by mass) or more. If the purity is lower than 2N, the durability may be lowered, or impurities may enter the liquid crystal side and baking may occur.

  The particle diameter of the primary particles of the raw material is preferably 3 μm or less, more preferably 1 μm or less, and still more preferably 0.5 μm or less. In particular, when the particle size of the compound of element X is large, it is unevenly distributed and exists as coarse particles, and there is a possibility that a homogeneous particle size suppressing effect may not appear in the entire sintered body. preferable.

It is preferable to mix the raw materials used for the production of the target such as metal oxide and uniformly mix and pulverize them using an ordinary mixing and pulverizing machine such as a wet ball mill, a bead mill or an ultrasonic device.
In addition, in order to improve the density of the molded body in the molding process described below or to suppress cracking of the molded body, molding aids such as polyvinyl alcohol (PVA), methylcellulose, polywax, oleic acid, etc. may be mixed. Furthermore, you may mix the mold release agent from a metal mold | die at the time of shaping | molding.
For example, when PVA is used as a dispersant, the amount of PVA used is preferably 5% by weight or less, more preferably 3% by weight or less, and still more preferably 2% by weight or less of the total amount of raw materials.
For example, stearic acid may be used as the mold release agent.

(2) Calcining step In the calcining step, the mixture obtained in the above step is calcined. In addition, this process is a process provided as needed. The calcining step makes it easy to increase the oxide density, but the production cost may increase. Therefore, it is more preferable that the density can be increased without performing calcination.
In the calcination step, it is preferable to heat-treat the above mixture at 500 to 1500 ° C. for 1 to 100 hours.

(3) Molding process The molding process is an indispensable process for pressure-molding the mixture obtained in the above-described blending process (or calcined product when the calcining process is provided) to form a compact. By this process, it is formed into a shape suitable as a target. When the calcination step is provided, the obtained calcined fine powder can be granulated and then molded into a desired shape by a molding process.
Examples of the molding process include press molding (uniaxial molding), mold molding, cast molding, injection molding, and the like. In order to obtain a target having a high sintered density, cold isostatic pressure (CIP) is used. It is preferable to mold.
In the case of simple press molding (uniaxial press), uneven pressure is generated, and an unexpected crystal form may be generated.
Moreover, after press molding (uniaxial pressing), cold isostatic pressure (CIP), hot isostatic pressure (HIP), etc. may be performed to provide two or more molding processes.

(4) Firing step The firing step is an essential step of firing the molded body obtained in the molding step.
Firing can be performed by atmospheric pressure firing or hot isostatic pressure (HIP) firing.
As firing conditions, it is preferable to obtain a step of degreasing moisture and molding aid in the molded body at 120 to 400 ° C. for 0.5 to 6 hours after the molded body is placed in the sintering furnace.
Thereafter, the temperature was raised to 800 to 1200 ° C. at a temperature rising rate of 0.5 to 5 ° C./min, and thereafter the sintering temperature was 1280 to 1500 ° C. at 0.1 to 3 ° C./min, which was slower than the temperature rising rate of the previous period. It is preferable to do. The sintering holding time is 5 to 72 hours, preferably 8 to 48 hours, and more preferably 10 to 36 hours.

In the temperature lowering process after firing, the temperature is decreased from 0.1 to 5 ° C./min up to 1000 to 1200 ° C. The temperature is preferably lowered at 0.2 to 3 ° C, more preferably 0.2 to 1 ° C / min. Further, the temperature is lowered at 1 to 5 ° C./min up to 300 to 500 ° C., and further cooled to the room temperature at a temperature lowering rate of 3 ° C./min or less.
The atmosphere to be baked may be air under atmospheric pressure, air circulation, oxygen circulation system, or oxygen pressurization. An atmosphere in an oxygen flow system is preferable because pores in the sintered body are reduced. The oxygen flow rate is preferably 0.1 to 100 L / min per 1 m ^{3 of} the furnace volume, although it depends on the furnace volume and the method of installing the molded body. In particular, when oxygen flows in a baking process at 1000 ° C. or higher, pores are reduced, which is effective.

(5) Reduction process The reduction process is for uniformizing the resistance of the sintered body obtained in the firing process over the entire target, and is a process provided as necessary. Examples of the reducing method that can be used include a method using a reducing gas, vacuum firing, or reduction using an inert gas.
In the case of reduction treatment with a reducing gas, hydrogen, methane, carbon monoxide, a mixed gas of these gases and oxygen, or the like can be used.
In the case of reduction treatment by firing in an inert gas, nitrogen, argon, a mixed gas of these gases and oxygen, or the like can be used.
The temperature at the time of a reduction process is 100-800 degreeC normally, Preferably it is 200-800 degreeC. The reduction treatment time is usually 0.01 to 10 hours, preferably 0.05 to 5 hours.

The sputtering target of the present invention is obtained by processing the oxide sintered body into a desired shape as necessary.
The processing is performed to cut the oxide sintered body into a shape suitable for mounting on a sputtering apparatus and to attach a mounting jig such as a backing plate. In order to use the oxide sintered body as a sputtering target, the sintered body is ground with a surface grinder, for example, to have a surface roughness Ra of 5 μm or less. Further, the sputter surface of the sputtering target may be mirror-finished so that the average surface roughness Ra is 1000 angstroms or less. For this mirror finishing (polishing), a known polishing technique such as mechanical polishing, chemical polishing, mechanochemical polishing (a combination of mechanical polishing and chemical polishing) can be used. For example, polishing to # 2000 or more with a fixed abrasive polisher (polishing liquid: water) or lapping with loose abrasive lapping (abrasive: SiC paste, etc.), and then lapping by changing the abrasive to diamond paste Can be obtained by: Such a polishing method is not particularly limited.

  The obtained sputtering target is bonded to a backing plate. Further, a plurality of targets may be attached to one backing plate to make a substantially single target.

  After polishing, the target is washed. For the cleaning treatment, air blow or running water cleaning can be used. When removing foreign matter by air blow, it is possible to remove the foreign matter more effectively by suctioning with a dust collector from the opposite side of the nozzle. In addition, since the above air blow and running water cleaning have a limit, ultrasonic cleaning etc. can also be performed. This ultrasonic cleaning is effective by performing multiple oscillations at a frequency of 25 to 300 KHz. For example, it is preferable to perform ultrasonic cleaning by causing multiple oscillations of 12 types of frequencies at intervals of 25 KHz between frequencies of 25 to 300 KHz. After washing, it is preferable to dry sufficiently at a temperature of 110 ° C. or less for 0.5 to 48 hours.

  The oxide thin film of the present invention is obtained by forming a film by a sputtering method using the above-described sputtering target of the present invention. The oxide thin film can also be manufactured by a vapor deposition method, an ion plating method, a pulse laser vapor deposition method, or the like using a sputtering target.

The oxide thin film of the present invention is preferably an amorphous film because electric characteristics, optical characteristics, and etching characteristics are uniform over a large area.
The fact that the oxide thin film is an amorphous film can be confirmed by the fact that the measurement result by X-ray diffraction does not show a specific crystal peak.
By adding ZrO ₂ and HfO ₂ , chemical resistance is improved, and back channel etching utilizing a difference in etching rate with the electrode becomes possible.

  The oxide thin film of the present invention can be used for a thin film transistor (TFT). In particular, it can be used as a channel layer. The TFT of the present invention only needs to have the oxide thin film of the present invention as a channel layer, and known components can be appropriately employed as the TFT structure and electrodes.

Example 1
Weigh indium oxide powder with a purity of 99.99%, tin dioxide powder with a purity of 99.99%, zinc oxide powder with a purity of 99.99%, and zirconium oxide powder so that the atomic ratio of each metal element satisfies the following: The mixture was then wet mixed and pulverized using a bead mill.
[In / (In + Sn + Zn + Zr)] = 0.5
[Sn / (In + Sn + Zn + Zr)] = 0.1
[Zn / (In + Sn + Zn + Zr)] = 0.3
[Zr / (In + Sn + Zn + Zr)] = 0.1
In addition, several kinds of zirconia beads having different particle diameters of 0.2 to 1 mmφ were used as the medium of the wet medium stirring mill. Moreover, 1 mass% of polyvinyl alcohol (PVA) was used as a shaping | molding adjuvant.
Each raw material was mixed and ground and then dried with a spray dryer. A mixed powder obtained by classifying coarse particles of 0.5 μm or more was filled in a mold, and uniaxial pressing and CIP molding were performed to produce a molded body (diameter 101.6 mm, thickness 8 mm).
The obtained molded body was dried and degreased at 300 ° C. for 2 hours in an oxygen stream of 1 L / min, and then fired at 1400 ° C. for 20 hours to produce an oxide sintered body. The heating rate was 1 ° C./min up to 1000 ° C., and then the temperature was raised at 0.5 ° C./min to reach the firing temperature. The temperature was lowered to 1000 ° C. at 0.5 ° C./min, to 500 ° C. at 1 ° C./min, and then cooled to 0.6 ° C./min in an air atmosphere.

The X-ray diffraction pattern of the obtained oxide sintered body is shown in FIG. It was confirmed by X-ray diffraction that an In ₂ O ₃ phase, a spinel phase (Zn ₂ SnO ₄ ), a ZrO ₂ phase, and an In ₂ O _3. (ZnO) ₃ phase were present in the sintered body.

FIG. 2 is a SEM photograph of a cross section of the oxide sintered body produced in Example 1. FIG. 3 is a diagram showing a distribution state of Zr atoms in the field of view of the SEM photograph of FIG. 2 by SEM-EDS. In FIG. 3, the bright portion shows a region having a high Zr concentration.
FIG. 4 is an EDS spectrum of the phase indicated by the arrow shown in the SEM photograph of FIG.
From FIG. 3, it can be confirmed that the ZrO ₂ phase is dispersed and segregated in the oxide sintered body of the present invention. Further, the EDS spectrum of FIG. 4, since the ZrO ₂ phase are present an In, an In was confirmed to be solid-solved in ZrO ₂ phase.
Table 1 shows the composition of the oxide sintered body, the firing conditions, and the crystal phase of the sintered body. Table 2 shows the resistance value, relative density, average particle size of the segregation phase (ZrO ₂ phase or HfO ₂ phase), and average particle size of all phases of the oxide sintered body.

The evaluation was carried out by the following method.
(1) Resistance value Measured with a low resistivity meter “Lorestar EP” (based on JIS K 7194) manufactured by Mitsubishi Chemical Corporation. Measurements were made at a total of 5 points, the intersection of two perpendicular diameters of the obtained circular sintered body, and the intersection and the middle point of the end, and the average value was taken as the resistance value.
(2) Relative Density The sample obtained by polishing the upper and lower surfaces of the obtained circular sintered body by 1 mm and further shaping the central part into a 2 × 2 × 0.5 cm rectangular parallelepiped was measured for the measured density by the Archimedes method. The relative density was calculated by dividing by the theoretical density.
(3) Average particle diameter of each crystal phase The upper and lower surfaces of the obtained circular sintered body were polished to a thickness of 5 mm. Furthermore, it shape | molded in diameter 101.6mmphi with the water jet cutting machine. The square inscribed in the circle is divided into 16 equal areas, and each center part is molded into a 1 × 1 × 0.5cm rectangular parallelepiped, embedded in resin and mirror-polished, and 16 pieces are used as samples. It was. The mirror polishing was performed until there were no cutting traces on the surface of the observation portion generated during sampling of the sintered body or polishing traces during rough cutting. The sample was coated with osmium for charge removal. An SEM observation (JEOL Co., Ltd. JSM-6390A, accelerating voltage 15 kV) was taken with an observation image having a size of 40 × 25 μm in a 3,000 × field of view. The diameter was measured, and the average value of the particle diameters of the particles in the frame of 16 samples was determined as the average particle diameter. The particle diameter was measured based on JIS R 1670 with crystal grains as equivalent circle diameters.
In addition, confirmation of the particles of HfO ₂ and ZrO ₂ phase was performed by an energy dispersive X-ray analyzer EDS apparatus (manufactured by JEOL Ltd., EX-2300) attached to the SEM. The position of each element by EDS was measured by mapping using each characteristic X-ray, and it was confirmed by EDS point element quantitative analysis of particles having high Hf and Zr concentrations that they were HfO ₂ phase and ZrO ₂ phase.
(4) Crystal phase Determined by X-ray diffraction measurement (XRD).
・ Device: ULTIMA-III manufactured by Rigaku Corporation
-X-ray: Cu-Kα ray (wavelength 1.5406mm, monochromatized with graphite monochromator)
・ 2θ-θ reflection method, continuous scan (1.0 ° / min)
・ Sampling interval: 0.02 °
・ Slit DS, SS: 2/3 °, RS: 0.6 mm

Examples 2-10, Comparative Examples 1-4
An oxide sintered body was produced and evaluated in the same manner as in Example 1 except that the oxide of element X shown in Table 1 was used and the atomic ratio of each metal atom and the firing temperature were changed. The results are shown in Tables 1 and 2.
FIG. 5 is a SEM photograph of a cross section of the oxide sintered body produced in Example 6. FIG. 6 is a diagram showing a distribution state of Hf atoms in the field of view of the SEM photograph of FIG. 5 by SEM-EDS. FIG. 7 is an EDS spectrum of the phase indicated by the arrow shown in the SEM photograph of FIG.
FIG. 6 confirms that the HfO ₂ phase is dispersed and segregated in the oxide sintered body of the present invention. Further, the EDS spectrum of FIG. 7, since the HfO ₂ phases are present an In, an In was confirmed that the solid solution in HfO ₂ phases.

  The oxide sintered body of the present invention can be used as a sputtering target. Since the sputtering target of the present invention can suppress arcing and is excellent in discharge stability, an oxide thin film having a large area and uniform characteristics can be obtained. A thin film formed using the sputtering target of the present invention can be used for a thin film transistor.

Claims (11)

Including each element of In, Sn and Zn,
Having at least one of HfO ₂ phase or ZrO ₂ phase,
The oxide sintered body, wherein the HfO ₂ phase and the ZrO ₂ phase have an average particle size of 10 μm or less.   2. The oxide sintered body according to claim 1, wherein an average particle diameter of all crystal phases is 10 μm or less. _3. The oxide sintered body according to claim 1, wherein at least one element of In or Sn is dissolved in the HfO ₂ phase and the ZrO ₂ phase. Further, at least one of phases selected from an In ₂ O ₃ phase, a Zn ₂ SnO ₄ phase, a ZnSnO ₃ phase, and an In ₂ O _3. (ZnO) _m (m is an integer of 1 or more) phase. The oxide sintered body according to claim 1, wherein the oxide sintered body is contained.   The oxide sintered body according to any one of claims 1 to 4, wherein a relative density is 95% or more.   The oxide sintered body according to any one of claims 1 to 5, wherein the resistance value is 2 mΩ or more and 100 mΩcm or less. The oxide sintered body according to any one of claims 1 to 6, wherein an atomic ratio of In, Sn, Zn, Hf, and Zr satisfies the following formulas (1) to (4).
0.20 ≦ In / (In + Sn + Zn + X) ≦ 0.70 (1)
0.01 ≦ Sn / (In + Sn + Zn + X) ≦ 0.40 (2)
0.01 ≦ Zn / (In + Sn + Zn + X) ≦ 0.60 (3)
0.002 ≦ X / (In + Sn + Zn + X) ≦ 0.25 (4)
(In the formula, X represents at least one element of Hf or Zr.)   A sputtering target obtained by processing the oxide sintered body according to claim 1.   An oxide thin film formed using the sputtering target according to claim 8.   The oxide thin film according to claim 9, which is an amorphous film.   A thin film transistor comprising the oxide thin film according to claim 9 or 10 as a channel layer.