WO2016017605A1

WO2016017605A1 - Sintered oxide

Info

Publication number: WO2016017605A1
Application number: PCT/JP2015/071304
Authority: WO
Inventors: 邦彦中田
Original assignee: 住友化学株式会社
Priority date: 2014-07-31
Filing date: 2015-07-28
Publication date: 2016-02-04
Also published as: KR20170039141A; JPWO2016017605A1; TW201609552A; CN106660881A

Abstract

The present invention provides, as a sintered oxide having high mechanical strength, high relative density, a low bulk resistance value, and a uniform composition, a sintered oxide including In, Ga, and Zn, wherein L* in the L*a*b* color system is 35 or less.

Description

Oxide sintered body

The present invention relates to an oxide sintered body.

An oxide semiconductor film formed from an oxide sintered body containing In, Ga, and Zn has an advantage of higher carrier mobility than an amorphous silicon film. In terms of mass productivity, this oxide semiconductor film is generally formed by a sputtering method using a sputtering target including an oxide sintered body containing In, Ga, and Zn.

As an oxide sintered body containing In, Ga, and Zn, for example, in Patent Document 1, the Vickers hardness is 724, the relative density is 96%, and the bulk resistance value is 9.5 × 10 ⁻⁴ Ω · Oxide sintered body that is cm, an oxide sintered body that has a Vickers hardness of 534, a relative density of 96%, and a bulk resistance value of 1.4 × 10 ⁻³ Ω · cm, and a Vickers hardness Is an oxide sintered body having a relative density of 97% and a bulk resistance value of 4.2 × 10 ⁻³ Ω · cm. Patent Document 2 discloses an InGaZnO ₄ single-phase oxide sintered body having a bending strength of 117 MPa and a relative density of 95.9%, a bending strength of 151 MPa, and a relative density of 96. 8% oxide sintered body and the InGaZnO ₄ single phase is bending strength is 157MPa, relative density oxide sintered body and the InGaZnO ₄ single phase is 96.1%, flexural strength 206MPa InGaZnO ₄ single-phase oxide sintered body having a relative density of 97.2% is described.

JP 2012-052227 A JP 2013-129545 A

An object of the present invention is to provide an oxide sintered body having a high mechanical strength, a high relative density, a low bulk resistance value, and a uniform composition.

In order to achieve the above object, the present invention provides the following inventions.

[1] An oxide sintered body containing In, Ga, and Zn, wherein L * in the L * a * b * color system is 35 or less.

[2] The oxide sintered body according to [1], wherein a * in the L * a * b * color system is −0.6 or less.

[3] The oxide sintered body according to [1] or [2], which has a Vickers hardness of 400 or more.

[4] The oxide sintered body according to any one of [1] to [3], wherein the bending strength is 90 MPa or more.

[5] The oxide sintered body according to any one of [1] to [4], wherein the relative density is 99.5% or more.

[6] The oxide sintered body according to any one of [1] to [5], wherein the bulk resistance value is less than 1.0 × 10 ⁻³ Ω · cm.

[7] The oxide sintered body according to any one of [1] to [6], wherein the single-phase ratio is 97.5% or more.

[8] The oxide sintered body according to any one of [1] to [7], wherein the crystal grain size is 9 μm or less.

[9] An oxide sintered body containing In, Ga, and Zn, having a Vickers hardness of 450 or more, a relative density exceeding 97%, and a bulk resistance value of less than 1.0 × 10 ⁻³ Ω · cm An oxide sintered body.

[10] An oxide sintered body containing In, Ga, and Zn, having a bending strength of 130 MPa or more, a relative density exceeding 97%, and a bulk resistance value of 1.0 × 10 ⁻³ Ω · cm Oxide sintered body which is less than.

[11] The oxide sintered body according to [10], having a Vickers hardness of 450 or more.

[12] The oxide sintered body according to any one of [9] to [11], wherein L * in the L * a * b * color system is 35 or less.

[13] The oxide sintered body according to any one of [9] to [12], wherein a * in the L * a * b * color system is −0.6 or less.

[14] The oxide sintered body according to any one of [9] to [13], wherein the relative density is 99.5% or more.

[15] The oxide sintered body according to any one of [9] to [14], wherein the single-phase ratio is 97.5% or more.

[16] The oxide sintered body according to any one of [9] to [15], wherein the crystal grain size is 4.5 μm or less.

[17] A sputtering target including the oxide sintered body according to any one of [1] to [16].

The oxide sintered body of the present invention has a high mechanical strength, a high relative density, a small bulk resistance value, and a uniform composition.

The oxide sintered body of the present invention contains indium (In), gallium (Ga), and zinc (Zn), further contains oxygen (O) as a constituent element, and preferably 99% or more of the atoms are indium. It consists of gallium, zinc, and oxygen and can be expressed by the following formula.

Formula: In _x Ga _y Zn _z O _a

[Wherein, x / (x + y) is 0.2 to 0.8, z / (x + y + z) is 0.1 to 0.5, and a = (3/2) x + (3/2) y + z It is. ]

For example, x: y: z = 1: 1: 1 can be represented as InGaZnO _4, and x: y: z = 2: 2: 1 can be represented as In ₂ Ga ₂ ZnO ₇ . These two compositions are preferable in terms of characteristics.

The oxide sintered body of the present invention preferably contains substantially no impurity metal element (M) such as Sn, Zr, Ti, Mo, Si, Cr, W, Ge, V, Mn, etc. The content [M / (In + Ga + Zn + M): weight ratio] of (M) is usually less than 10 ppm. The content of the impurity metal element (M) in the oxide sintered body can be measured by a high frequency inductively coupled plasma (ICP) analyzer.

L * in the L * a * b * color system of the oxide sintered body of the present invention is usually 35 or less, preferably 34.5 or less, more preferably 34 or less, and still more preferably 33. .5 or less.

The a * in the L * a * b * color system of the oxide sintered body of the present invention is usually −0.6 or less, preferably −1.0 or less.

L * and a * in the L * a * b * color system of the oxide sintered body of the present invention are the surface roughness (Ra) of the surface of the oxide sintered body with abrasive paper by a wet polishing machine. After performing wet polishing until the thickness becomes 0.5 μm or less, the chromaticity a *, chromaticity b *, and lightness L * of the polished surface are measured with a spectrocolorimeter, and the results are evaluated in the CIE 1976 space. This can be calculated.

Before measuring L * and a * in the L * a * b * color system of the oxide sintered body of the present invention, L *, a * and b * in the L * a * b * color system It is preferable to use a known sample as a standard sample and measure its L *, a * and b * to confirm whether or not it matches the known value.

The Vickers hardness of the oxide sintered body of the present invention is usually 400 or more, preferably 405 or more, more preferably 450 or more, and further preferably 470 or more. Since the oxide sintered body of the present invention has a high Vickers hardness, it is particularly suitable as a target in the DC sputtering method, and even when the generation of particles is small and the sputtering power is high, the target is not cracked and is formed. The speed can be increased and the oxide semiconductor film can be manufactured with good production efficiency.

The bending strength of the oxide sintered body of the present invention is usually 90 MPa or more, preferably 95 MPa or more, more preferably 130 MPa or more, and further preferably 150 MPa or more. Since the oxide sintered body of the present invention has a high bending strength, it is particularly suitable as a target in the DC sputtering method, and even when the generation of particles is small and the sputtering power is high, the target is not cracked and is formed. The film speed can be increased, and the oxide semiconductor film can be manufactured with good production efficiency.

The relative density of the oxide sintered body of the present invention usually exceeds 97%, preferably 99% or more, more preferably 99.5% or more, and further preferably 99.7% or more.

The “relative density” in the present specification is the ratio of the density of the oxide sintered body actually obtained to the theoretical density of the oxide sintered body, and is obtained from the following formula.

Relative density (%) = 100 × [(density of oxide sintered body) / (theoretical density of oxide sintered body)]

The density of the oxide sintered body can be measured by a length measurement method.

The theoretical density of an oxide sintered body is, in principle, a value obtained by multiplying the single element density of each metal oxide that is the raw material of the oxide sintered body by the mixing weight ratio of each metal oxide powder and taking the sum of these. Yes, when the oxide sintered body is made of indium oxide, gallium oxide and zinc oxide, it can be obtained from the following formula.

Theoretical density of sintered oxide = (Indium oxide simple substance density x mixing weight ratio) + (Gallium oxide simple substance density x mixing weight ratio) + (Zinc oxide simple substance density x mixing weight ratio)

In addition, information on single-phase crystals with the same metal atom ratio as the metal oxide ratio in the mixed powder of metal oxide, which is the raw material of the oxide sintered body, is described on the JCPDS (Joint Committee of Powder Diffraction Standards) card. The theoretical density of the crystal described in the JCPDS card can be used as the theoretical density in the above formula.

For example, when indium oxide powder, gallium oxide powder, and zinc oxide powder are mixed so that the atomic ratio of indium, gallium, and zinc (In: Ga: Zn) is 1: 1: 1, the JCPDS card Describes information on single-phase crystals of InGaZnO ₄ (In: Ga: Zn = 1: 1: 1), the theoretical density of single-phase crystals of InGaZnO ₄ described in the JCPDS card (No. 381104) (6 .379 g / cm ³ ) can be the theoretical density in the above formula.

For example, when indium oxide powder, gallium oxide powder and zinc oxide powder are mixed so that the atomic ratio (In: Ga: Zn) of indium, gallium and zinc is 2: 2: 1, the JCPDS card The theoretical density (6.495 g / cm ³ ) of the single phase crystal of In ₂ Ga ₂ ZnO ₇ (In: Ga: Zn = 2: 2: 1) described in (No. 381097) can do.

If the proportion of metal atoms in the mixed powder does not match the proportion of metal atoms in the single-phase crystal described in the JCPDS card, but the deviation is within 5%, the single atom described in the JCPDS card The theoretical density of the phase crystal can be the theoretical density in the above formula.

The bulk resistance value of the oxide sintered body of the present invention is usually less than 1.0 × 10 ⁻³ Ω · cm, preferably 9 × 10 ⁻⁴ Ω · cm or less, and more preferably 8.5 ×. 10 ⁻⁴ Ω · cm or less. Since the oxide sintered body of the present invention is also excellent in conductivity, it is particularly suitable as a target in the DC sputtering method, and from the oxide sintered body of the present invention, there is no abnormal discharge, stably and at high speed. A uniform semiconductor film can be formed efficiently.

The bulk resistance value can usually be measured with a resistivity meter.

The single phase ratio of the oxide sintered body of the present invention is usually 97.5% or more, preferably 99% or more, more preferably 99.5% or more, and further preferably 99.7% or more. It is.

In the present specification, the single phase ratio means a content ratio of InGaZnO ₄ or In ₂ Ga ₂ ZnO ₇ which is a homologous crystal structure contained in the oxide sintered body. The single phase ratio can be calculated by X-ray diffraction measurement of the oxide sintered body. Specifically, the oxide sintered body is measured by X-ray diffraction, and the obtained X-ray diffraction pattern is an X-ray diffraction pattern of InGaZnO ₄ or In ₂ Ga ₂ ZnO ₇ having a homologous crystal structure (for example, JCPDS (Joint It is confirmed whether or not the homologous phase crystal structure X-ray diffraction pattern obtained from the Committee of Powder Diffraction Standards card). When the obtained X-ray diffraction pattern matches the crystal structure X-ray diffraction pattern of the homologous phase obtained from the JCPDS card, and there is no peak that is not attributed to the diffraction pattern of the crystal structure of the homologous phase, the single-phase ratio is 100 %. On the other hand, if there is a peak that does not belong to the diffraction pattern of the crystal structure of the homologous phase in the obtained X-ray diffraction pattern, the peak that is not assigned is identified, and the crystal structure of the homologous phase in the oxide sintered body And the sum of the proportions of the other crystal structures are taken as 100%, and the proportion of the homologous crystal structure is derived by Rietveld analysis.

The crystal grain size of the oxide sintered body of the present invention is usually 9 μm or less, preferably 8 μm or less, more preferably 4.5 μm or less, still more preferably less than 4.0 μm, and further preferably It is 3.5 μm or less, more preferably 2 μm or less. In the present specification, the crystal grain size of the oxide sintered body is measured as follows. SEM-EBSD measurement was performed on the oxide sintered body, and the area (cross-sectional area) of each individual particle was measured by image analysis of the obtained Image Quality Map. The diameter of the circle was calculated assuming that the cross section of the grain was the closest circle. The calculated diameter was multiplied by the occupation ratio of the grains with respect to the entire area, and the diameter per occupied area of the grains was calculated. For all the grains, the diameter per occupied area was calculated, and the total of the calculated diameters per occupied area was defined as the area average diameter, that is, the crystal grain size.

[Production Method of Oxide Sintered Body (1)]
One form of the manufacturing method of the oxide sintered compact of this invention includes the following process (A) and process (B).

Step (A): A step of mixing indium oxide powder, gallium oxide powder, and zinc oxide powder to obtain a mixed powder.

Step (B): A step of filling the mixed powder obtained in the step (A) into a capsule container and subjecting the capsule container filled with the mixed powder to hot isostatic pressing of the capsule.

The mixing of the indium oxide powder, the gallium oxide powder, and the zinc oxide powder in the step (A) is, when converted to the atomic ratio of the metal element, In: Ga: Zn = x: y: z, x / (x + y) is 0.2 to 0.8 and z / (x + y + z) is performed so as to satisfy the relationship of 0.1 to 0.5, and In: Ga: Zn = 1: 1: 1 or 2: 2: It is preferable to perform mixing so as to be 1.

The average particle diameter of the indium oxide powder in the mixed powder obtained in the step (A) is less than 0.6 μm. The average particle diameter of the powder is a 50% cumulative volume fraction particle diameter in a particle size distribution measured by a laser diffraction / scattering method.

In step (B), the filling rate of the mixed powder obtained in step (A) into the capsule container is 50% or more, preferably 55% or more, and more preferably 60% or more. Here, the filling rate is calculated by the following equation.

Filling rate (%) = (tap density of mixed powder / theoretical density of oxide sintered body) × 100

In step (A), after calcining at least one powder selected from the group consisting of indium oxide powder, gallium oxide powder and zinc oxide powder, these powders are mixed to obtain a mixed powder, or indium oxide powder And gallium oxide powder and zinc oxide powder are mixed, and the obtained mixed powder is calcined to obtain a mixed powder. Thus, in step (B), the filling rate of the mixed powder is easily set to 50% or more. can do. In the step (A), it is preferable to mix indium oxide powder, gallium oxide powder, and zinc oxide powder and calcine the obtained mixed powder to obtain a mixed powder.

In the step (A), when calcining at least one powder selected from the group consisting of indium oxide powder, gallium oxide powder and zinc oxide powder and then mixing these powders to obtain a mixed powder, preferably indium oxide Each of the powder, gallium oxide powder and zinc oxide powder is calcined separately, and the calcined powders are mixed to obtain a mixed powder. Since the tap density of indium oxide powder is not easily increased by calcining, the mixed powder is composed of calcined indium oxide powder, calcined gallium oxide powder and calcined zinc oxide powder, or is not calcined. It is preferably made of indium oxide powder, calcined gallium oxide powder and calcined zinc oxide powder. In particular, in order to manufacture an oxide sintered body represented by In ₂ Ga ₂ ZnO ₇ , the molar ratio (In: Ga: Zn) of indium oxide powder: gallium oxide powder: zinc oxide powder is 2: 2: When the mixing ratio is 1, it is preferable to prepare a mixed powder made of calcined indium oxide powder, calcined gallium oxide powder and calcined zinc oxide powder.

By making the filling rate of the mixed powder into the capsule container 50% or more, the shrinkage rate of the capsule container in the capsule hot isostatic pressing process (capsule HIP process) can be made 50% or less. The mixed powder can be pressure-sintered without destroying, and volatilization of zinc derived from the zinc oxide powder and indium derived from the indium oxide powder during the production of the sintered body can be suppressed. The shrinkage rate of the capsule container is represented by the following formula.

Shrinkage rate of capsule container (%) = [1− (inner volume of capsule container after capsule HIP treatment / inner volume of capsule container before capsule HIP process)] × 100

In order to avoid the adverse effect of impurities on the electrical characteristics of the oxide sintered body, the purity of indium oxide (In ₂ O ₃ ) powder, gallium oxide (Ga ₂ O ₃ ) powder and zinc oxide (ZnO) powder is 4N or more Is preferred.

In this specification, the tap density is based on JIS K5101. After a powder of a certain volume is filled with a natural drop, an impact due to a certain vibration (tapping) is further applied to the container, and the volume change of the powder disappears. It means the mass of powder per unit volume. The mass of powder per unit volume when the powder is filled into a container with a certain volume by natural dropping and the inner volume is taken as the volume is called bulk density. Generally, the tap density is the bulk density. 1.1 to 1.3 times as large as

As the indium oxide powder, a commercially available indium oxide powder is usually used. The tap density of commercially available indium oxide powder is usually 1.95 g / cm ³ or less, although it varies depending on the average particle size and particle size distribution. The simple substance density (upper limit of tap density) of indium oxide is 7.18 g / cm ³ .

When the indium oxide powder is calcined, a calcining apparatus such as a vertical electric furnace, a tubular furnace, a muffle furnace, a tube furnace, a hearth raising / lowering electric furnace, a box type electric furnace or the like is usually used.

The calcination temperature is usually 1200 to 1600 ° C., preferably 1400 to 1600 ° C. The calcination time is usually 8 hours or more and 24 hours or less, preferably 10 hours or more and 15 hours or less. The tap density of the indium oxide powder after calcination is preferably 2.70 g / cm ³ or more, more preferably 3.0 g / cm ³ or more.

The calcination may be performed in an atmospheric atmosphere, an oxidizing atmosphere such as an oxidizing atmosphere having a higher oxygen concentration than the air, an inert gas atmosphere such as nitrogen, argon, helium, vacuum, carbon dioxide, hydrogen, You may perform in non-oxidizing atmospheres, such as reducing gas atmospheres, such as carbon monoxide, hydrogen sulfide, and sulfur dioxide. It is preferable to calcine in an oxidizing atmosphere.

The calcined indium oxide powder may be crushed by a known means such as a George crusher, a roll crusher, a stamp mill, a hammer mill, or a mortar.

As the gallium oxide powder, a commercially available gallium oxide powder is usually used. The tap density of commercially available gallium oxide powder varies depending on the average particle size and particle size distribution, but is usually 1.45 g / cm ³ or less. The single-piece density (upper limit of tap density) of gallium oxide is 5.88 g / cm ³ .
The average particle diameter of the gallium oxide powder is usually 0.2 μm or more and 5 μm or less, preferably 0.2 μm or more and 2 μm or less.

The calcination of the gallium oxide powder is usually performed in the same manner as the calcination of the indium oxide powder. The tap density of the calcined gallium oxide powder is preferably 4.0 g / cm ³ or more. It is preferable to perform calcination in an oxidizing atmosphere.

As the zinc oxide powder, commercially available zinc oxide powder is usually used. The tap density of commercially available gallium oxide powder varies depending on the average particle size and particle size distribution, but is usually 1.12 g / cm ³ or less. The single-piece density (upper limit of tap density) of zinc oxide is 5.6 g / cm ³ .

The average particle diameter of the zinc oxide powder is usually 0.6 μm or more and 5 μm or less, preferably 1 μm or more and 5 μm or less.

The calcination of the zinc oxide powder is usually performed in the same manner as the calcination of the indium oxide powder. The tap density of the calcined zinc oxide powder is preferably 4.1 g / cm ³ or more. It is preferable to perform calcination in an oxidizing atmosphere.

When mixing indium oxide powder: gallium oxide powder: zinc oxide powder at approximately 50.8: 34.3: 14.9 (weight ratio, molar ratio In: Ga: Zn = 2: 2: 1) The tap density of the mixed powder is preferably 3.25 g / cm ³ or more, and the capsule container can be filled with a large amount of the mixed powder, and the capsule container after the capsule HIP treatment contracts symmetrically and becomes easy to process. Therefore, it is more preferably 3.8 to 6.4 g / cm ³ .

When mixing indium oxide powder: gallium oxide powder: zinc oxide powder at approximately 44.2: 29.9: 25.9 (weight ratio, molar ratio In: Ga: Zn = 1: 1: 1) The tap density of the mixed powder is preferably 3.18 g / cm ³ or more, more preferably 3.8 to 6.3 g / cm ³ .

The mixing method of each powder is not limited as long as the powder can be uniformly mixed, and may be dry-mixed by a super mixer, intensive mixer, Henschel mixer, automatic mortar, etc., ball mill, vibration mill, planetary ball mill, etc. May be wet mixed.
If uniform mixing is insufficient, each component segregates in the manufactured target, and the resistance distribution of the target becomes non-uniform. That is, the high resistance region and the low resistance region exist depending on the target site, which causes abnormal discharge such as arcing due to charging in the high resistance region during sputtering film formation.

When indium oxide powder, gallium oxide powder, and zinc oxide powder are mixed and the obtained mixed powder is calcined to obtain a mixed powder, the calcined mixed powder is usually also calcined as described above. It is carried out in the same way as firing. Preferably, the calcining temperature is 1200 to 1650 ° C., preferably 1400 to 1600 ° C. in an oxidizing atmosphere. The tap density of the mixed powder after calcination is preferably 3.18 g / cm ³ or more, more preferably 3.8 to 6.3 g / cm ³ .

In step (B), the capsule powder is filled with the above-described mixed powder, and then the capsule HIP treatment is performed to obtain the oxide sintered body of the present invention. The mixed powder is enclosed in a vacuum-sealed capsule container. Since the mixed powder is filled in the enclosed space and the capsule HIP process is performed, volatilization of zinc and indium is suppressed unlike pressure sintering such as hot pressing, and as a result, the obtained oxide sintered body and The composition does not easily deviate from the raw material mixed powder, and an oxide sintered body having a high relative density and a high single-phase ratio can be obtained.

The material of the capsule container usually includes iron, stainless steel, titanium, aluminum, stainless steel, tantalum, niobium, copper and nickel, and can be appropriately selected depending on the processing temperature of the capsule HIP process. When the processing temperature is in the low temperature range (1000 ° C. or lower), a capsule container made of copper, nickel or aluminum is usually used. When the processing temperature is in the range of 1000 ° C. to 1350 ° C., it is made of iron, titanium or stainless steel. Capsule containers are usually used. In the region where the processing temperature is higher than 1350 ° C., capsule containers made of tantalum or niobium are usually used. Depending on the treatment temperature, capsule containers made of aluminum, iron or stainless steel are preferable in terms of cost.

The shape and dimensions of the capsule container are not limited as long as it is isotropically pressurized during the capsule HIP process. Specifically, a cylindrical container and a rectangular parallelepiped container are mentioned.
The wall thickness of the capsule container is preferably 1.5 mm to 4 mm. Within this range, the capsule container can be easily softened and deformed, and can shrink following the oxide sintered body as the sintering reaction proceeds.

After filling the mixed powder into the capsule container, the pressure in the capsule container is usually decreased to 1.33 × 10 ⁻² Pa or less while heating the capsule container to 100 ° C. or more and 600 ° C. or less. When the pressure in the capsule container becomes 1.33 × 10 ⁻² Pa or less, the capsule container is sealed and the capsule HIP process is performed.

Capsule HIP treatment is performed by placing a sealed capsule container filled with mixed powder in a HIP apparatus, applying pressure to the capsule container itself using a gas under high temperature and high pressure as a pressure medium, and mixing the capsule container The powder is pressure sintered.

As the pressure medium, an inert gas such as nitrogen or argon is preferable. The pressure applied to the capsule container is preferably 50 MPa or more. The treatment time is preferably 1 hour or longer.
The treatment temperature is usually 1000 to 1400 ° C., preferably 1100 ° C. to 1300 ° C. It is preferable that the sintering temperature is 1000 ° C. to 1400 ° C. and the pressure is 50 MPa or more and the treatment is performed for 1 hour or more.

[Production Method of Oxide Sintered Body (2)]
Another form of the method for producing an oxide sintered body of the present invention includes the following step (a), step (b) and step (c).

Step (b): A step of molding or granulating the mixed powder obtained in step (a) to obtain a molded body or granulated powder.

Step (c): a step of filling the molded body or granulated powder obtained in the step (b) into a capsule container, and subjecting the capsule container filled with the molded body or the granulated powder to isostatic pressing.

The mixing of the indium oxide powder, the gallium oxide powder and the zinc oxide powder in the step (a) is x / (x + y) where In: Ga: Zn = x: y: z in terms of the atomic ratio of the metal element. 0.2 to 0.8 and z / (x + y + z) is performed so as to satisfy the relationship of 0.1 to 0.5, and In: Ga: Zn = 1: 1: 1 or 2: 2: It is preferable to perform mixing so as to be 1.

In this specification, the tap density is based on JIS K5101. After filling a container of a certain volume with powder by natural dropping, the container is further subjected to an impact by a certain vibration (tapping), and the volume change of the powder is eliminated. It means the mass of powder per unit volume. The mass of powder per unit volume when the powder is filled into a container with a certain volume by natural dropping and the inner volume is taken as the volume is called bulk density. Generally, the tap density is the bulk density. 1.1 to 1.3 times as large as

In step (b), when the mixed powder obtained in step (a) is molded to obtain a molded body, it is preferable to perform pressure molding to obtain the molded body. An example of a method for pressure-molding the mixed powder is a cold isostatic pressing method. The pressure during pressure molding is usually 50 to 300 MPa, preferably 100 to 300 MPa.

To press-mold the mixed powder, for example, a uniaxial press, a cold isostatic press (CIP), or the like can be used. When molding, a uniaxial press and a cold isostatic press (CIP) may be used in combination.

In the case of uniaxial pressing, the pressing pressure when forming the mixed powder is preferably at least 30 MPa and less than 100 MPa, more preferably 40 MPa or more. If it is less than 30 MPa, there is a possibility that a stable press-molded body cannot be produced. If it is 100 MPa or more, the molded product may be brittle and easily cracked.

In order to increase the density of the molded body to 3.19 g / cm ³ or more, pressure molding is preferably performed at a pressing pressure of 40 to 90 MPa, more preferably 50 to 80 MPa.

In the case of cold isostatic pressing (CIP), the pressing pressure is preferably at least 50 MPa and less than 400 MPa, more preferably 100 MPa or more. If it is less than 50 MPa, there is a possibility that a stable press-molded product cannot be produced. If it is 400 MPa or more, the apparatus becomes too large, which is uneconomical and the molded product may be fragile. The holding time is 1 to 30 minutes. If the holding time is less than 1 minute, the density may not increase, and if it exceeds 60 minutes, it may take too much time and be uneconomical.

In order to obtain a molded body more easily, an organic binder may be blended into the mixed powder and molded. When producing a large sintered body having a side of 300 mm or more or a diameter of 300 mm or more, an organic binder is preferably blended.

The addition amount of the organic binder is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the mixed powder.

When using an organic binder, the raw material powder and the organic binder are mixed to form a mixed powder, and pressure molded to form a pressure molded body. And before performing a capsule HIP process to this press-molded body, an organic binder is usually removed.

Organic binders include butyral resin, polyvinyl alcohol, acrylic resin, poly α-methylstyrene, ethyl cellulose, polymethyl lactate, (poly) vinyl butyral, (poly) vinyl acetate, (poly) vinyl alcohol, polyethylene, polystyrene, polybutadiene, (Poly) vinyl pyrrolidone, polyamide, polyethylene oxide, polypropylene oxide, polyacrylamide, polymethacrylate and various acrylic polymers and their copolymers and terpolymers, resins such as methylcellulose, ethylcellulose, hydroxyethylcellulose, nitrocellulose and their derivatives Etc.

The method of blending the organic binder includes a method of mixing the raw material powder, the organic binder, and a solvent and drying the resulting slurry.

After the pressure molding, the obtained molded body may be processed by cutting, grinding or the like according to the shape and size of the capsule container used in the step (c).

In the step (b), when the mixed powder obtained in the step (a) is granulated to obtain a granulated powder, the mixed powder, a solvent and an organic binder are mixed, and the resulting slurry is granulated, It is preferable to obtain a granular powder. Examples of the granulation method include rolling granulation, fluidized bed (spouted bed) granulation, stirring and mixing granulation, compression granulation, extrusion granulation, pulverization granulation, melt granulation, spray granulation, and the like. Examples of the granulator include a bread granulator, a trough granulator, a compression granulator, and a spray dryer. As the granulation format, either dry or wet can be selected, but wet granulation using the adhesive force of water or a binder (binder) is preferable. Among these, a spray dryer is preferable.

As the solvent used in preparing the slurry, water, an alcohol solvent and a ketone solvent are preferable in terms of uniformity of the particle size distribution of the mixed powder and easy evaporation of the solvent. Examples of the alcohol solvent include methanol, ethanol, and isopropyl alcohol, and examples of the ketone solvent include acetone, methyl ethyl ketone, and cyclohexanone. Halogenated hydrocarbon solvents such as methyl chloride, chloroform, 1,2 dichloroethane and trichloroethylene, ester solvents such as methyl acetate, ethyl acetate, propylene carbonate and propyl acetate, nitrogen-containing solvents such as propiontolyl and N-methylpyrrolidone, dimethyl sulfoxide Sulfur-containing solvents such as tetrahydrofuran, dioxane, propylene oxide, ether solvents such as 2-ethoxyethyl acetate, and hydrocarbon solvents such as benzene and styrene can also be used. The amount of the solvent used is usually 60 to 200 parts by mass with respect to 100 parts by mass of the mixed powder.

The wet mixing may be performed by, for example, a wet ball mill using a hard ZrO ₂ ball or a vibration mill, and the mixing time when using the wet ball mill or the vibration mill is preferably about 12 to 78 hours.

The slurry is supplied to a normal spray dryer, sprayed and dried to obtain a granulated powder. At this time, the inlet temperature is usually set to 180 to 250 ° C., and the outlet temperature is usually set to 90 to 130 ° C.

When indium oxide powder: gallium oxide powder: zinc oxide powder is mixed at about 50.8: 34.3: 14.9 (weight ratio, molar ratio In: Ga: Zn = 2: 2: 1), The density of the molded body or the tap density of the granulated powder is preferably 3.25 g / cm ³ or more, and the capsule container can be filled with many molded bodies or granulated powder, and the capsule container after the capsule HIP treatment Is more preferably 3.8 to 6.4 g / cm ³ , since it shrinks symmetrically to facilitate processing.

When mixing indium oxide powder: gallium oxide powder: zinc oxide powder at approximately 44.2: 29.9: 25.9 (weight ratio, molar ratio In: Ga: Zn = 1: 1: 1) The density of the molded body or the tap density of the granulated powder is preferably 3.18 g / cm ³ or more, more preferably 3.8 to 6.3 g / cm ³ .

In step (c), the filling rate of the molded product or granulated powder obtained in step (b) into the capsule container is 50% or more, preferably 55% or more, and preferably 60% or more. Is more preferable. Here, the filling rate is calculated by the following equation.

Filling rate (%) = (packing density of molded body or tap density of granulated powder / theoretical density of oxide sintered body) × 100

Note that the filling density of the molded body is calculated by the following formula.

Filling density = weight of molded body / inner volume of capsule container

By setting the filling rate of the molded body or granulated powder in the capsule container to 50% or more, the shrinkage rate of the capsule container in the capsule hot isostatic pressing process (capsule HIP process) can be set to 50% or less. Therefore, the molded body or granulated powder can be pressure-sintered without destroying the capsule container, and the volatilization of zinc derived from zinc oxide powder or indium derived from indium oxide powder during the production of the sintered body can be suppressed. . The shrinkage rate of the capsule container is represented by the following formula.

In step (c), the capsule body is filled with the above-mentioned molded body or granulated powder, and then capsule HIP treatment is performed to obtain the oxide sintered body of the present invention. The molded body or the granulated powder is enclosed in a vacuum sealed capsule container. Since the molded body or granulated powder is filled in the enclosed space and capsule HIP treatment is performed, volatilization of zinc and indium is suppressed unlike pressure sintering such as hot pressing, and the resulting oxide The composition does not easily shift between the sintered body and the molded body or granulated powder as the raw material, and an oxide sintered body having a high relative density and a high single-phase ratio can be obtained.

The material of the capsule container usually includes iron, stainless steel, titanium, aluminum, tantalum, niobium, copper and nickel, and can be appropriately selected depending on the processing temperature of the capsule HIP processing. When the processing temperature is in the low temperature range (1000 ° C. or lower), a capsule container made of copper, nickel or aluminum is usually used. When the processing temperature is in the range of 1000 ° C. to 1350 ° C., a capsule container made of iron or stainless steel Is usually used. In the region where the processing temperature is higher than 1350 ° C., capsule containers made of tantalum or niobium are usually used. Depending on the treatment temperature, capsule containers made of aluminum, iron or stainless steel are preferable in terms of cost.

After the molded body or granulated powder is filled in the capsule container, the capsule container is usually heated to remove the binder contained in the molded body, the solvent contained in the granulated powder, and the organic binder. Thereafter, the capsule container is sealed and a capsule HIP process is performed. Further, the pressure in the capsule container may be decreased to 1.33 × 10 ⁻² Pa or less while heating the capsule container filled with the molded body or the granulated powder to 100 ° C. or more and 600 ° C. or less. . Thereby, the solvent and organic binder which are contained in the binder and granulated powder which are contained in a molded object are removed. When the pressure in the capsule container becomes 1.33 × 10 ⁻² Pa or less, the capsule container is sealed and the capsule HIP process is performed.

Capsule HIP treatment is performed by placing a sealed capsule container filled with a molded body or granulated powder in a HIP apparatus, applying pressure to the capsule container itself using a gas under high temperature and high pressure as a pressure medium, The mixed powder in the container is subjected to pressure sintering.

[Sputtering target]
A sputtering target can be manufactured by processing the oxide sintered body of the present invention into a predetermined shape and a predetermined dimension. For the oxide sintered body of the present invention, for example, a sputtering target having an outer diameter of 152 mm × 5 mm can be produced by cylindrical grinding of the outer periphery and surface grinding of the surface side. The surface roughness (Ra) of the sputtering target is preferably 5 μm or less, and more preferably 0.5 μm or less. Usually, the sputtering target is further used in a form in which an indium alloy or the like is bonded as a bonding metal to a backing plate or backing tube made of copper, titanium, or the like.

The method of manufacturing the sputtering target by processing the oxide sintered body of the present invention is not limited, and a known method is employed.

The sputtering target is used for film formation by sputtering, ion plating, pulse laser deposition (PLD), or electron beam (EB) evaporation. Since the target of the present invention has a high relative density and a high single-phase ratio, abnormal discharge during film formation hardly occurs and film formation can be performed stably. Note that a solid material used in the film formation may be referred to as a “tablet”, but in the present specification, these are referred to as a “sputtering target”.
In addition, since the sputtering target of the present invention has a high relative density and a high single-phase ratio, the frequency of nodules and the frequency of abnormal discharge can be reduced as the sputtering time elapses. Production efficiency is also improved, and the resulting film properties are excellent. With the oxide sintered body or sputtering target of the present invention, a transparent semiconductor film having good characteristics as a channel layer of a thin film transistor exhibiting stable semiconductor characteristics can be formed.

The film thickness of the transparent semiconductor film is usually 0.5 to 500 nm, preferably 1 to 150 nm, more preferably 3 to 80 nm, from the viewpoint of a semiconductor having high mobility and low S value. The thickness is preferably 10 to 60 nm. If it is 0.5 nm or more, it is possible to form an industrially uniform film. On the other hand, if it is 500 nm or less, the film formation time will not be too long. When the thickness is in the range of 3 to 80 nm, TFT characteristics such as mobility and on / off ratio are particularly good.

Examples of the sputtering method include a DC sputtering method, an AC sputtering method, an RF magnetron sputtering method, an electron beam evaporation method, and an ion plating method, and a DC sputtering method is preferable.
In the case of DC sputtering, the pressure in the chamber during sputtering is usually 0.1 to 2.0 MPa, preferably 0.3 to 0.8 MPa. For DC sputtering input power per unit area of the target surface during sputtering is usually 0.5 ~ 6.0W / cm ^2, preferably 1.0 ~ 5.0W / cm ^2. Examples of the carrier gas at the time of sputtering include oxygen, helium, argon, xenon, and krypton, and a mixed gas of argon and oxygen is preferable. The ratio of argon: oxygen (Ar: O ₂ ) in the mixed gas of argon and oxygen is usually 100: 0 to 80:20, preferably 99.5: 0.5 to 80:20, more preferably Is 99.5: 0.5 to 90:10. Examples of the substrate include glass and resin (PET, PES, etc.). The film formation temperature during sputtering (the temperature of the substrate on which the thin film is formed) is usually 25 ° C. to 450 ° C., preferably 30 ° C. to 250 ° C., more preferably 35 ° C. to 150 ° C.

<Measurement of particle size distribution of powder>
The particle size distribution of each powder was measured with a laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation), and the volume cumulative standard D50 was defined as the average particle size. Further, the shape and size of the powder were measured by FE-SEM.

<Measurement of crystal grain size of oxide sintered body>
SEM-EBSD measurement of the oxide sintered body was performed under the conditions of an acceleration voltage of 15 kV, a working distance of 15 mm, and a magnification of 1500 times, and the area (cross-sectional area) of each individual particle was measured by image analysis of the obtained Image Quality Map. did. The diameter of the circle was calculated assuming that the cross section of the grain was the closest circle. The calculated diameter was multiplied by the occupation ratio of the grains with respect to the entire area, and the diameter per occupied area of the grains was calculated. For all the grains, the diameter per occupied area was calculated, and the total of the calculated diameters per occupied area was defined as the area average diameter, that is, the crystal grain size.

<Measurement of Vickers hardness of sintered oxide>
The Vickers hardness of the oxide sintered body was measured by a micro hardness meter (HMV) manufactured by Shimadzu Corporation.

<Measurement of bending strength of sintered oxide>
The bending strength of the oxide sintered body was measured in accordance with JIS R1601 using a universal material testing machine (Instron 5584 (load cell 5 kN)).
Test method: 3-point bending test fulcrum distance: 30 mm
Supporting anvil: R = 2mm
Pressurized anvil: R = 3mm
Sample size: 3x4x40mm
Head speed: 0.5 mm / min
Test temperature: 22 ° C

<Measurement of color difference of sintered oxide>
Using a wet polishing machine (Malto Wrap Co., Ltd. manufactured by Maruto Co., Ltd.), the surface of the oxide sintered body is polished to a surface roughness (Ra) of 0.5 μm using polishing paper (# 60) and then polishing paper (# 180). Wet polishing was performed until the following. The polished surface was measured for chromaticity a *, chromaticity b *, and lightness L * with a spectrocolorimeter (Z-300A manufactured by Nippon Denshoku Industries Co., Ltd.), and the results were evaluated in the CIE 1976 space.

[Example 1]
Indium oxide powder (manufactured by Rare Metal Co., Ltd., tap density: 1.62 g / cm ³ , average particle size: 0.56 μm) and gallium oxide powder (manufactured by Yamanaka Futec Co., Ltd., tap density: 1.39 g / cm ³ , average particle diameter: 1.5 μm), zinc oxide powder (manufactured by Hakusuitec Co., Ltd., tap density: 1.02 g / cm ³ , average particle diameter: 1.5 μm), indium element and gallium element Weighing was performed so that the atomic ratio with zinc element (In: Ga: Zn) was 1: 1: 1, and dry mixing was performed with a super mixer at 3000 rpm for 60 minutes to obtain a mixed powder.

The obtained mixed powder was put into an electric furnace (manufactured by Kitahama Corporation), heated in the atmosphere at a heating rate of 10 ° C./min from room temperature to 1400 ° C., and calcined at 1400 ° C. for 12 hours Went. The obtained powder was lightly pulverized in a mortar to obtain a mixed powder after calcining.

The mixed powder after calcining was filled into a stainless steel (SUS304) capsule container (outer diameter 83 mm, inner diameter 80 mm, height 78 mm inside the container) while applying vibration until the volume of the mixed powder disappeared. The tap density of the mixed powder is 4.32 g / cm ^3, since the theoretical density of 6.379g / cm ^3, the filling ratio was 67.7%. As the theoretical density, information on a single crystal of InGaZnO ₄ (JCPDS card number: 381104) having a composition ratio In: Ga: Zn = 1: 1: 1 is described in the JCPDS card. The single crystal theoretical density (6.379 g / cm ³ ) was employed.

The exhaust pipe was welded to the upper lid of the capsule container filled with the mixed powder, and then the upper lid and the capsule container were welded. A He leak test was performed to confirm whether there was any gas leak from the welded portion of the capsule container. The amount of leakage at this time was 1 × 10 ⁻⁶ Torr · L / sec or less. After removing the gas in the capsule container from the exhaust pipe at 550 ° C. for 7 hours, the exhaust pipe was closed and the capsule container was sealed. The sealed capsule container was placed in a HIP processing apparatus (manufactured by Kobe Steel, Ltd.) and subjected to capsule HIP processing. The treatment temperature was 1200 ° C., the treatment pressure was 118 MPa, and the treatment was performed for 4 hours using argon gas (purity 99.9%) as a pressure medium.
After the capsule HIP treatment, the capsule container was removed to obtain a cylindrical oxide sintered body.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 8.31 × 10 ⁻⁴ Ω · cm. The density of the sintered body was measured by a length measurement method, and the theoretical density of InGaZnO ₄ (JCPDS card number: 381104) described in the JCPDS card was adopted as the theoretical density of the sintered body.

When the obtained oxide sintered body was observed with an electron microscope, it was a dense sintered body with almost no pores.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), only the diffraction peak attributed to InGaZnO ₄ having a homologous structure was observed. Since no diffraction peak attributed to the phase was observed, the (1114) single phase ratio was 100%.

The obtained oxide sintered body had an average crystal grain size of 6.8 μm, a Vickers hardness of 411.0, and a bending strength of 100 MPa.

L * of the obtained oxide sintered body was 28.77, a * was −0.69, b * was −4.07, and ΔL was 68.51.

The surface of the obtained oxide sintered body was ground, the outer periphery was ground, and the surface was further polished to prepare a sintered body having a diameter of 50.8 mm and a thickness of 3 mm. When the prepared sintered body was analyzed with an ICP (High Frequency Inductively Coupled Plasma) analyzer (SEIKO Co., Ltd. SPS5000), the atomic ratio of In, Ga and Zn (In: Ga: Zn) was 1: 1: 1 The atomic ratio of In, Ga, and Zn in this sintered body was the same as the raw material composition (In: Ga: Zn = 1: 1: 1), and there was no volatilization of indium or zinc during the production of the sintered body. It shows that.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 8.31 × 10 ⁻⁴ Ω · cm. Because of its low density, high density, no defects as a sputtering target, and sufficient DC sputtering, it is possible to suppress the occurrence of abnormal discharge and to efficiently form a uniform oxide semiconductor film. It was.

[Example 2]
In Example 1, using gallium oxide powder having an average particle diameter of 0.6 μm, and carrying out the same procedure as in Example 1 except that the filling rate of the mixed powder after calcining into the capsule container was set to 66.5%. An oxide sintered body was obtained.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 8.21 × 10 ⁻⁴ Ω · cm.

The average grain size of the obtained oxide sintered body was 8.9 μm, the Vickers hardness was 410.1, and the bending strength was 99 MPa.

L * of the obtained oxide sintered body was 32.49, a * was −2.27, b * was −3.47, and ΔL was 64.79.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 8.21 × 10 ⁻⁴ Ω · cm. Because of its low density, high density, no defects as a sputtering target, and sufficient DC sputtering, it is possible to suppress the occurrence of abnormal discharge and to efficiently form a uniform oxide semiconductor film. It was.

[Example 3]
The same procedure as in Example 1 was performed except that gallium oxide powder having an average particle diameter of 0.3 μm was used in Example 1, and the filling rate of the mixed powder after calcining into the capsule container was set to 65.7%. An oxide sintered body was obtained.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 8.11 × 10 ⁻⁴ Ω · cm.

The average grain size of the obtained oxide sintered body was 7.3 μm, the Vickers hardness was 422.3, and the bending strength was 105 MPa.

L * of the obtained oxide sintered body was 31.42, a * was -2.14, b * was -3.23, and ΔL was 65.84.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 8.11 × 10 ⁻⁴ Ω · cm. Because of its low density, high density, no defects as a sputtering target, and sufficient DC sputtering, it is possible to suppress the occurrence of abnormal discharge and to efficiently form a uniform oxide semiconductor film. It was.

[Example 4]
In Example 1, the mixture is weighed so that the atomic ratio (In: Ga: Zn) of indium element, gallium element, and zinc element is 2: 2: 1, and the mixed powder after calcination is filled into the capsule container The oxide sintered body was obtained in the same manner as in Example 1 except that the rate was 63.3%.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 5.65 × 10 ⁻⁴ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), only a diffraction peak attributed to In ₂ Ga ₂ ZnO ₇ having a homologous structure was observed. Since no diffraction peaks attributed to other crystal phases were observed, the (2217) single-phase ratio was 100%.

The average grain size of the obtained oxide sintered body was 7.0 μm, the Vickers hardness was 408.3, and the bending strength was 98 MPa.

L * of the obtained oxide sintered body was 29.78, a * was −1.22, b * was −3.88, and ΔL was 67.50.

The surface of the obtained oxide sintered body was ground, the outer periphery was ground, and the surface was further polished to prepare a sintered body having a diameter of 50.8 mm and a thickness of 3 mm. When the prepared sintered body was analyzed with an ICP (high frequency inductively coupled plasma) analyzer (SEIKO Co., Ltd. SPS5000), the atomic ratio of In, Ga and Zn (In: Ga: Zn) was 2: 2: 1 The atomic ratio of In, Ga, and Zn in this sintered body was the same as the raw material composition (In: Ga: Zn = 2: 2: 1), and there was no volatilization of indium or zinc during the production of the sintered body. It shows that.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (2217) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 5.65 × 10 ⁻⁴ Ω · cm. Because of its low density, high density, no defects as a sputtering target, and sufficient DC sputtering, it is possible to suppress the occurrence of abnormal discharge and to efficiently form a uniform oxide semiconductor film. It was.

[Example 5]
In Example 1, gallium oxide powder having an average particle size of 0.6 μm was used and weighed so that the atomic ratio (In: Ga: Zn) of indium element, gallium element and zinc element was 2: 2: 1. And it implemented like Example 1 except the filling rate to the capsule container of the mixed powder after calcination having been 62.8%, and obtained oxide sinter.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 5.53 × 10 ⁻⁴ Ω · cm.

The average grain size of the obtained oxide sintered body was 7.2 μm, the Vickers hardness was 408.5, and the bending strength was 98 MPa.

L * of the obtained oxide sintered body was 33.21, a * was -2.38, b * was -3.33, and ΔL was 64.07.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, (2217) a single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 5.53 × 10 ⁻⁴ Ω · cm. Because of its low density, high density, no defects as a sputtering target, and sufficient DC sputtering, it is possible to suppress the occurrence of abnormal discharge and to efficiently form a uniform oxide semiconductor film. It was.

[Example 6]
In Example 1, gallium oxide powder having an average particle size of 0.3 μm was used and weighed so that the atomic ratio (In: Ga: Zn) of indium element, gallium element, and zinc element was 2: 2: 1. And it implemented like Example 1 except having made the filling rate to the capsule container of the mixed powder after calcination 61.5%, and obtained oxide sinter.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 5.43 × 10 ⁻⁴ Ω · cm.

The average grain size of the obtained oxide sintered body was 7.1 μm, the Vickers hardness was 411.3, and the bending strength was 100 MPa.

L * of the obtained oxide sintered body was 32.32, a * was −2.30, b * was −3.16, and ΔL was 64.90.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (2217) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 5.43 × 10 ⁻⁴ Ω · cm. Because of its low density, high density, no defects as a sputtering target, and sufficient DC sputtering, it is possible to suppress the occurrence of abnormal discharge and to efficiently form a uniform oxide semiconductor film. It was.

[Example 7]
Indium oxide powder (made by rare metal), tap density: 1.62 g / cm ³ , average particle diameter: 0.56 μm) and gallium oxide powder (made by rare metal, Inc., tap density 1.50 g) / Cm ³ , average particle size: 1.0 μm), zinc oxide powder (manufactured by Hakusui Tech Co., Ltd., tap density: 1.02 g / cm ³ , average particle size: 1.5 μm), indium element and gallium element And zinc element were weighed so that the atomic ratio (In: Ga: Zn) was 1: 1: 1, and dry mixing was performed with a super mixer at 3000 rpm for 60 minutes to obtain a mixed powder.

The mixed powder after calcining was filled into a stainless steel (SUS304) capsule container (outer diameter 83 mm, inner diameter 80 mm, height 78 mm inside the container) while applying vibration until the volume of the mixed powder disappeared. The tap density of the mixed powder is 4.10 g / cm ^3, since the theoretical density of 6.379g / cm ^3, the filling ratio was 64.3%. As the theoretical density, information on a single crystal of InGaZnO ₄ (JCPDS card number: 381104) having a composition ratio In: Ga: Zn = 1: 1: 1 is described in the JCPDS card. The single crystal theoretical density (6.379 g / cm ³ ) was employed.

The exhaust pipe was welded to the upper lid of the capsule container filled with the mixed powder, and then the upper lid and the capsule container were welded. A He leak test was performed to confirm whether there was any gas leak from the welded portion of the capsule container. The amount of leakage at this time was 1 × 10 ⁻⁶ Torr · L / sec or less. After removing the gas in the capsule container from the exhaust pipe at 550 ° C. for 7 hours, the exhaust pipe was closed and the capsule container was sealed. The sealed capsule container was placed in a HIP processing apparatus (manufactured by Kobe Steel, Ltd.) and subjected to capsule HIP processing. The treatment temperature was 1220 ° C., the treatment pressure was 118 MPa, and the treatment was performed for 4 hours using argon gas (purity 99.9%) as a pressure medium.
After the capsule HIP treatment, the capsule container was removed to obtain a cylindrical oxide sintered body.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 8.40 × 10 ⁻⁴ Ω · cm. The density of the sintered body was measured by a length measurement method, and the theoretical density of InGaZnO ₄ (JCPDS card number: 381104) described in the JCPDS card was adopted as the theoretical density of the sintered body.

The obtained oxide sintered body had an average crystal grain size of 2.1 μm, a Vickers hardness of 521.4, and a bending strength of 152 MPa.

L * of the obtained oxide sintered body was 32.02, a * was -0.72, b * was -1.15, and ΔL was 65.14.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (resistivity) of 8.40 × 10 ⁻⁴ Ω · cm. Because of its low density, high density, no defects as a sputtering target, and sufficient DC sputtering, it is possible to suppress the occurrence of abnormal discharge and to efficiently form a uniform oxide semiconductor film. It was.
[Comparative Example 1]
In Example 1, gallium oxide powder having an average particle diameter of 3 μm was used, calcining was not performed, and the filling rate of the mixed powder (tap density: 2.21 g / cm ³ ) into the capsule container was set to 34.8%. Except for this, the same procedure as in Example 1 was performed, but the capsule burst and an oxide sintered body was not obtained.

[Comparative Example 2]
In Example 1, an indium oxide powder having an average particle size of 1 μm was used, and the same procedure as in Example 1 was performed except that the filling rate of the mixed powder after calcining into the capsule container was 57.4%. A sintered product was obtained.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 6.3 × 10 ⁻⁴ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to InGaZnO ₄ having a homologous structure, An assigned diffraction peak was also observed. (1114) The single phase ratio was 90.20%.

The average grain size of the obtained oxide sintered body was 6.9 μm, the Vickers hardness was 398.6, and the bending strength was 98 MPa.

L * of the obtained oxide sintered body was 35.89, a * was −0.21, b * was −4.99, and ΔL was 61.48.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 90.2%, and a bulk resistance value (specific resistance) of 6.3 × 10 ⁻⁴ Ω · cm. For this reason, the uniformity of the composition of the sputtered film was reduced although it was high density.

[Comparative Example 3]
In Comparative Example 2, the mixture was weighed so that the atomic ratio (In: Ga: Zn) of indium element, gallium element, and zinc element was 2: 2: 1, and the mixed powder after calcination was filled into the capsule container An oxide sintered body was obtained in the same manner as in Comparative Example 2 except that the rate was changed to 54.2%.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 4.50 × 10 ⁻⁴ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to In ₂ Ga ₂ ZnO ₇ having a homologous structure, A diffraction peak attributed to the crystalline phase was also observed. (2217) The single phase ratio was 84.50%.

The average grain size of the obtained oxide sintered body was 7.0 μm, the Vickers hardness was 396.4, and the bending strength was 97 MPa.

L * of the obtained oxide sintered body was 36.45, a * was −0.34, b * was −4.87, and ΔL was 60.90.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (2217) single-phase ratio of 84.5%, and a bulk resistance value (specific resistance) of 4.5 × 10 ⁻⁴ Ω · cm. For this reason, the uniformity of the composition of the sputtered film was reduced although it was high density.

[Comparative Example 4]
In Comparative Example 2, the same procedure as in Comparative Example 2 was performed except that gallium oxide powder having an average particle diameter of 0.6 μm was used and the filling rate of the mixed powder after calcining into the capsule container was 63.1%. An oxide sintered body was obtained.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 6.30 × 10 ⁻⁴ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined by an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to InGaZnO ₄ , diffraction attributed to other crystal phases A peak was also observed. (1114) The ratio of single phase was 90.40%.

The average grain size of the obtained oxide sintered body was 7.2 μm, the Vickers hardness was 392.4, and the bending strength was 93 MPa.

L * of the obtained oxide sintered body was 36.56, a * was −0.34, b * was −5.12, and ΔL was 60.80.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 90.4%, and a bulk resistance value (specific resistance) of 6.3 × 10 ⁻⁴ Ω · cm. For this reason, the uniformity of the composition of the sputtered film was reduced although it was high density.

[Comparative Example 5]
In Comparative Example 2, gallium oxide powder having an average particle diameter of 0.6 μm was used and weighed so that the atomic ratio (In: Ga: Zn) of indium element, gallium element, and zinc element was 2: 2: 1. And it implemented similarly to the comparative example 2 except the filling rate to the capsule container of the mixed powder after calcination having been 59.9%, and obtained oxide sinter.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 4.30 × 10 ⁻⁴ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to In ₂ Ga ₂ ZnO ₇ having a homologous structure, A diffraction peak attributed to the crystalline phase was also observed. (2217) The ratio of single phase was 83.80%.

The obtained oxide sintered body had an average crystal grain size of 7.4 μm, a Vickers hardness of 390.2, and a bending strength of 92 MPa.

L * of the obtained oxide sintered body was 37.5, a * was −0.56, b * was −4.74, and ΔL was 59.90.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (2217) single-phase ratio of 83.8%, and a bulk resistance value (specific resistance) of 4.3 × 10 ⁻⁴ Ω · cm. Therefore, although the density was high, the uniformity of the composition of the sputtered film was reduced.

[Example 8]
Indium oxide powder (manufactured by Rare Metal Co., Ltd., tap density: 1.62 g / cm ³ , average particle size: 0.56 μm) and gallium oxide powder (manufactured by Yamanaka Futec Co., Ltd., tap density: 1.39 g / cm ³ , average particle size: about 1.5 μm), zinc oxide powder (manufactured by Hakusui Tech Co., Ltd., tap density: 1.02 g / cm ³ , average particle size: about 1.5 μm), indium element and gallium Weighing was performed so that the atomic ratio of the element and zinc element (In: Ga: Zn) was 1: 1: 1, and dry mixing was performed with a super mixer at 3000 rpm for 1 hour to obtain a mixed powder.

The obtained mixed powder was subjected to pressure molding at a pressure of 300 MPa by a cold isostatic pressing method, and the obtained molded product was cut to obtain a cylindrical molded body having a diameter of 115 mm and a height of 40 mm. The density of the cylindrical molded body was 3.52 g / cm ³ .

The density of the molded body was calculated by measuring the diameter and height of the molded body, calculating the volume, and dividing the separately measured weight of the molded body by the calculated volume.

The cylindrical molded body was transferred to a capsule container (outer diameter 121 mm, inner diameter 115 mm, inner height 40 mm) made of stainless steel (SUS304) so that the molded body did not collapse and filled into the capsule container. The filling density of the mixed powder was 3.52 g / cm ³ , and the theoretical density of the sintered body was 6.379 g / cm ³ , so that the filling rate of the mixed powder was 55.2%. As the theoretical density, information on a single crystal of InGaZnO ₄ (JCPDS card number: 381104) having a composition ratio In: Ga: Zn = 1: 1: 1 is described in the JCPDS card. The single crystal theoretical density (6.379 g / cm ³ ) was employed.

The exhaust pipe was welded to the upper lid of the capsule container filled with the cylindrical molded body, and then the upper lid and the capsule container were welded. A He leak test was performed to confirm whether there was any gas leak from the welded portion of the capsule container. The amount of leakage at this time was 1 × 10 ⁻⁶ Torr · L / sec or less. After removing the gas in the capsule container from the exhaust pipe at 550 ° C. for 7 hours, the exhaust pipe was closed and the capsule container was sealed. The sealed capsule container was placed in a HIP processing apparatus (manufactured by Kobe Steel, Ltd.) and subjected to capsule HIP processing. The treatment temperature was 1200 ° C., the treatment pressure was 118 MPa, and the treatment was performed for 4 hours using argon gas (purity 99.9%) as a pressure medium. After the capsule HIP treatment, the capsule container was removed to obtain a cylindrical oxide sintered body. The obtained cylindrical oxide sintered body had a diameter of 94.3 mm and a height of 32.8 mm.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 8.18 × 10 ⁻⁴ Ω · cm. The density of the sintered body was measured by a length measurement method, and the theoretical density of InGaZnO ₄ (JCPDS card number: 381104) described in the JCPDS card was adopted as the theoretical density of the sintered body.

The average grain size of the obtained oxide sintered body was 0.77 μm, the Vickers hardness was 648.1, and the bending strength was 210 MPa.

L * of the obtained oxide sintered body was 22.08, a * was −1.03, b * was −2.48, and ΔL was 75.1.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 8.18 × 10 ⁻⁴ Ω · cm. It has a high density, no defects as a sputtering target, a low resistance value sufficient for DC sputtering, a small crystal grain size, a fine structure, and a high Vickers hardness, resulting in less generation of particles. Production can be suppressed (suppressing the occurrence of abnormal discharge), and since the mechanical strength is high, the film formation rate can be increased without cracking the target even if the sputtering power is increased, and the production efficiency is good. .

[Example 9]
In Example 8, a gallium oxide powder having an average particle size of 3 μm was used, and the filling rate of the cylindrical molded body into the capsule container was changed to 57.4%. A ligature was obtained.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 9.80 × 10 ⁻⁴ Ω · cm.

The obtained oxide sintered body had an average crystal grain size of 4.2 μm, Vickers hardness of 473.1, and flexural strength of 133 MPa.

L * of the obtained oxide sintered body was 33.67, a * was −1.94, b * was −3.53, and ΔL was 63.6.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 9.8 × 10 ⁻⁴ Ω · cm. It has a high density, no defects as a sputtering target, a low resistance value sufficient for DC sputtering, a small crystal grain size, a fine structure, and a high Vickers hardness, resulting in less generation of particles. Production can be suppressed (suppressing the occurrence of abnormal discharge), and since the mechanical strength is high, the film formation rate can be increased without cracking the target even if the sputtering power is increased, and the production efficiency is good. .

[Example 10]
In Example 8, the same procedure as in Example 8 was performed except that gallium oxide powder having an average particle size of 0.3 μm was used and the filling rate of the cylindrical molded body into the capsule container was 54.4%. A sintered product was obtained.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 7.54 × 10 ⁻⁴ Ω · cm.

The obtained oxide sintered body had an average crystal grain size of 0.92 μm, Vickers hardness of 652.3, and bending strength of 212 MPa.

L * of the obtained oxide sintered body was 21.98, a * was −0.99, b * was −2.39, and ΔL was 75.2.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 7.54 × 10 ⁻⁴ Ω · cm. It has a high density, no defects as a sputtering target, a low resistance value that allows DC sputtering sufficiently, a small crystal grain size, a fine structure, and a high Vickers hardness. The generation can also be suppressed (the occurrence of abnormal discharge is suppressed), and since the mechanical strength is high, the film formation rate can be increased without cracking the target even when the sputtering power is increased, and the production efficiency is good.

[Example 11]
In Example 8, a gallium oxide powder having an average particle diameter of 1 μm was used, and the filling rate of the cylindrical molded body into the capsule container was changed to 55.1%. A ligature was obtained.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 9.20 × 10 ⁻⁴ Ω · cm.

The obtained oxide sintered body had an average crystal grain size of 3.5 μm, Vickers hardness of 538.5, and flexural strength of 162 MPa.

L * of the obtained oxide sintered body was 27.46, a * was −1.45, b * was −3.03, and ΔL was 69.8.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 100%, and a bulk resistance value (resistivity) of 9.2 × 10 ⁻⁴ Ω · cm. It has a high density, no defects as a sputtering target, a low resistance value sufficient for DC sputtering, a small crystal grain size, a fine structure, and a high Vickers hardness, resulting in less generation of particles. Production can be suppressed (suppressing the occurrence of abnormal discharge), and since the mechanical strength is high, the film formation rate can be increased without cracking the target even if the sputtering power is increased, and the production efficiency is good. .

[Example 12]
Indium oxide powder (manufactured by Rare Metal Co., Ltd., tap density: 1.62 g / cm ³ , average particle size: 0.56 μm) and gallium oxide powder (manufactured by Yamanaka Futec Co., Ltd., tap density: 1.39 g / cm ³ , average particle size: about 1.5 μm), zinc oxide powder (manufactured by Hakusui Tech Co., Ltd., tap density: 1.02 g / cm ³ , average particle size: about 1.5 μm), indium element and gallium Weighing was performed so that the atomic ratio of element to zinc element (In: Ga: Zn) was 1: 1: 1, and the weighed powders were mixed to obtain a mixed powder.

The obtained mixed powder, polypropylene carbonate (molecular weight: 200,000), 2 mmφ zirconia balls, ethanol and acetone were mixed to prepare a slurry, and the slurry was wet-mixed by a wet ball mill mixing method. In addition, 2 mass parts of polypropylene carbonate was used with respect to 98 mass parts of mixed powder.

After removing the zirconia balls from the slurry, the slurry is sprayed with an explosion-proof spray dryer (DL410 manufactured by Yamato Scientific Co., Ltd.) equipped with a two-fluid nozzle type (orifice diameter 0.7 mm) atomizer and dried at normal pressure. And granulated to obtain a granulated powder having a particle size of 95 μm and a tap density of 3.43 g / cm ³ . The temperature of the hot air supplied to the spray dryer was 250 ° C., and the temperature at the outlet of the dryer was 93 ° C.

The particle size of the granulated powder was measured as follows.

Part of the granulated powder is collected, the collected powder and hexametaphosphoric acid (dispersing agent) are put into water, irradiated with ultrasonic waves for 3 minutes, and then a laser diffraction / scattering particle size distribution analyzer (Beckman Coulter, Inc.) The particle size distribution was measured by LS-230, manufactured, and the particle size of the granulated powder was defined as a particle size with an integrated volume fraction of 50%.

The tap density of the granulated powder was calculated based on JIS K5101 by filling the granulated powder into a graduated cylinder of a predetermined size while applying vibration until the volume of the granulated powder disappeared.

Fill the granule powder into a capsule container made of stainless steel (SUS304) (outer diameter 83 mm, inner diameter 80 mm, height 78 mm inside the container) while applying vibration until the volume of the granulated powder disappears. did. Tap density of the granulated powder is 3.43 g / cm ^3, the theoretical density of the sintered body is filling rate of the mixed powder since it is 6.379g / cm ³ was 53.8%. As the theoretical density, information on a single crystal of InGaZnO ₄ (JCPDS card number: 381104) having a composition ratio In: Ga: Zn = 1: 1: 1 is described in the JCPDS card. The single crystal theoretical density (6.379 g / cm ³ ) was employed.

The capsule container filled with the granulated powder was kept at 400 ° C. for 5 hours in an air atmosphere to remove the polypropylene carbonate. The tap density of the powder after removing the polypropylene carbonate was 3.31 g / cm ³ , and the filling rate was 51.9%.

The exhaust pipe was welded to the upper lid of the capsule container, and then the upper lid and the capsule container were welded. A He leak test was performed to confirm whether there was any gas leak from the welded portion of the capsule container. The amount of leakage at this time was 1 × 10 ⁻⁹ Pa · m ³ / sec or less. After removing the gas in the capsule container from the exhaust pipe at 550 ° C. for 7 hours, the exhaust pipe was closed and the capsule container was sealed. The sealed capsule container was placed in a HIP processing apparatus (manufactured by Kobe Steel, Ltd.) and subjected to capsule HIP processing. The treatment temperature was 1200 ° C., the treatment pressure was 118 MPa, and the treatment was performed for 4 hours using argon gas (purity 99.9%) as a pressure medium. After the capsule HIP treatment, the capsule container was removed to obtain a cylindrical oxide sintered body. The obtained cylindrical oxide sintered body had a diameter of 64.1 mm and a height of 62.4 mm.

[Example 13]
In Example 12, the atomic ratio (In: Ga: Zn) of indium element, gallium element, and zinc element was weighed to be 2: 2: 1, and the filling rate of the granulated powder into the capsule container was 56. The oxide sintered body was obtained in the same manner as in Example 12 except that the content was 2%.

The average grain size of the obtained oxide sintered body was 0.93 μm, the Vickers hardness was 610.3, and the bending strength was 195 MPa.

L * of the obtained oxide sintered body was 19.62, a * was −0.46, b * was −0.346, and ΔL was 77.52.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (2217) single-phase ratio of 100%, and a bulk resistance value (specific resistance) of 5.43 × 10 ⁻⁴ Ω · cm. It has a high density, no defects as a sputtering target, a low resistance value sufficient for DC sputtering, a small crystal grain size, a fine structure, and a high Vickers hardness, resulting in less generation of particles. Production can be suppressed (suppressing the occurrence of abnormal discharge), and since the mechanical strength is high, the film formation rate can be increased without cracking the target even if the sputtering power is increased, and the production efficiency is good. .

[Example 14]
In Example 8, a zinc oxide powder having an average particle diameter of 60 nm was used, and the same procedure as in Example 8 was performed except that the filling rate of the mixed powder after calcining into the capsule container was 54.6%. A sintered product was obtained.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 8.18 × 10 ⁻⁴ Ω · cm.

The obtained oxide sintered body had an average crystal grain size of 0.72 μm, Vickers hardness of 674.1, and flexural strength of 225 MPa.

L * of the obtained oxide sintered body was 21,82, a * was −1.01, b * was −2.43, and ΔL was 75.4.

[Example 15]
Indium oxide powder (made by rare metal), tap density: 1.62 g / cm ³ , average particle diameter: 0.56 μm) and gallium oxide powder (made by rare metal, Inc., tap density 1.50 g) / Cm ³ , average particle size: 1.0 μm), zinc oxide powder (manufactured by Hakusui Tech Co., Ltd., tap density: 1.02 g / cm ³ , average particle size: 1.5 μm), indium element and gallium element And zinc element were weighed so that the atomic ratio (In: Ga: Zn) was 1: 1: 1, and dry mixing was performed with a super mixer at 3000 rpm for 1 hour to obtain a mixed powder.

The obtained mixed powder was subjected to pressure molding at a pressure of 300 MPa by a cold isostatic pressing method, and the obtained molded product was cut to obtain a cylindrical molded body having a diameter of 115 mm and a height of 40 mm. The density of the cylindrical molded body was 3.66 g / cm ³ .

The cylindrical molded body was transferred to a capsule container (outer diameter 121 mm, inner diameter 115 mm, inner height 40 mm) made of stainless steel (SUS304) so that the molded body did not collapse and filled into the capsule container. The filling density of the mixed powder was 3.66 g / cm ³ , and the theoretical density of the sintered body was 6.379 g / cm ³ , so that the filling rate of the mixed powder was 57.3%. As the theoretical density, information on a single crystal of InGaZnO ₄ (JCPDS card number: 381104) having a composition ratio In: Ga: Zn = 1: 1: 1 is described in the JCPDS card. The single crystal theoretical density (6.379 g / cm ³ ) was employed.

The exhaust pipe was welded to the upper lid of the capsule container filled with the cylindrical molded body, and then the upper lid and the capsule container were welded. A He leak test was performed to confirm whether there was any gas leak from the welded portion of the capsule container. The amount of leakage at this time was 1 × 10 ⁻⁶ Torr · L / sec or less. After removing the gas in the capsule container from the exhaust pipe at 550 ° C. for 7 hours, the exhaust pipe was closed and the capsule container was sealed. The sealed capsule container was placed in a HIP processing apparatus (manufactured by Kobe Steel, Ltd.) and subjected to capsule HIP processing. The treatment temperature was 1220 ° C., the treatment pressure was 118 MPa, and the treatment was performed for 4 hours using argon gas (purity 99.9%) as a pressure medium. After the capsule HIP treatment, the capsule container was removed to obtain a cylindrical oxide sintered body. The obtained cylindrical oxide sintered body had a diameter of 94.3 mm and a height of 32.8 mm.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 8.30 × 10 ⁻⁴ Ω · cm. The density of the sintered body was measured by a length measurement method, and the theoretical density of InGaZnO ₄ (JCPDS card number: 381104) described in the JCPDS card was adopted as the theoretical density of the sintered body.

The average grain size of the obtained oxide sintered body was 1.20 μm, the Vickers hardness was 595.0, and the bending strength was 188 MPa.

L * of the obtained oxide sintered body was 34.2, a * was −1.55, b * was −2.93, and ΔL was 63.0.

[Comparative Example 6]
Example 8 was carried out in the same manner as in Example 8 except that indium oxide powder having an average particle size of 4.0 μm (manufactured by Kojundo Chemical Laboratory Co., Ltd.) was used. .6 mm, height 32.9 mm). The density of the cylindrical molded body was 3.55 g / cm ³ . The capsule container was filled with a cylindrical molded body, and the calculated filling density was 3.55 g / cm ³ . Therefore, the filling rate of the cylindrical molded body into the capsule container was 55.7%.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 1.1 × 10 ⁻³ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to InGaZnO ₄ having a homologous structure, An assigned diffraction peak was also observed. (1114) The ratio of single phase was 70%.

The obtained oxide sintered body had an average crystal grain size of 7.9 μm, a Vickers hardness of 421.3, and a bending strength of 107 MPa.

L * of the obtained oxide sintered body was 35.32, a * was −2.08, b * was −0.367, and ΔL was 59.5.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 70%, and a bulk resistance value (specific resistance) of 1.1 × 10 ⁻³ Ω · cm. Although the density was high, the uniformity of the composition of the sputtered film was reduced.

[Comparative Example 7]
In Comparative Example 6, the atomic ratio of indium element, gallium element, and zinc element (In: Ga: Zn) was weighed to be 2: 2: 1, and the filling rate of the cylindrical molded body into the capsule container was determined. An oxide sintered body was obtained in the same manner as in Comparative Example 6 except that the content was 55.9%.

The relative density of the obtained oxide sintered body was 100%, and the bulk resistance value (specific resistance) was 1.7 × 10 ⁻² Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to In ₂ Ga ₂ ZnO ₇ having a homologous structure, A diffraction peak attributed to the crystalline phase was also observed. (2217) The single phase ratio was 4%.

The average grain size of the obtained oxide sintered body was 8.3 μm, the Vickers hardness was 398.5, and the bending strength was 96 MPa.

L * of the obtained oxide sintered body was 45.8, a * was −2.83, b * was −3.97, and ΔL was 51.6.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (2217) single-phase ratio of 4%, and a bulk resistance value (specific resistance) of 1.7 × 10 ⁻² Ω · cm. Although the density was high, the uniformity of the composition of the sputtered film was reduced.

[Comparative Example 8]
In Comparative Example 6, the same procedure as in Comparative Example 6 was performed except that indium oxide powder having an average particle size of 1.0 μm was used and the filling rate of the cylindrical molded body into the capsule container was set to 56.6%. A sintered product was obtained.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 6.2 × 10 ⁻⁴ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to InGaZnO ₄ having a homologous structure, An assigned diffraction peak was also observed. (1114) The single phase ratio was 88.60%.

The obtained oxide sintered body had an average crystal grain size of 4.8 μm, a Vickers hardness of 421.3, and a bending strength of 107 MPa.

L * of the obtained oxide sintered body was 38.3, a * was −1.88, b * was −2.54, and ΔL was 58.9.

This oxide sintered body was bonded with indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (1114) single-phase ratio of 88.60%, and a bulk resistance value (specific resistance) of 6.2 × 10 ⁻⁴ Ω · cm. For this reason, the uniformity of the composition of the sputtered film was reduced although it was high density.

[Comparative Example 9]
In Comparative Example 8, the atomic ratio of indium element, gallium element and zinc element (In: Ga: Zn) was weighed to be 2: 2: 1, and the filling rate of the cylindrical molded body into the capsule container was determined. An oxide sintered body was obtained in the same manner as in Comparative Example 8 except that the content was 54.8%.

The obtained oxide sintered body had a relative density of 100% and a bulk resistance value (specific resistance) of 4.2 × 10 ⁻⁴ Ω · cm.

When the crystal structure of the obtained oxide sintered body was examined with an X-ray diffractometer (EMPYREAN manufactured by Panalical Co., Ltd.), in addition to the diffraction peak attributed to In ₂ Ga ₂ ZnO ₇ having a homologous structure, A diffraction peak attributed to the crystalline phase was also observed. (2217) The ratio of single phase was 85.60%.

The average grain size of the obtained oxide sintered body was 4.7 μm, the Vickers hardness was 436.2, and the bending strength was 114 MPa.

L * of the obtained oxide sintered body was 39.4, a * was -1.93, b * was -3.21, and ΔL was 57.9.

This oxide sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target. Using this, an oxide semiconductor film was formed on a transparent substrate (non-alkali glass substrate) by a DC sputtering method to obtain a transparent semiconductor substrate. This oxide sintered body has a relative density of 100%, a (2217) single-phase ratio of 85.6%, and a bulk resistance value (specific resistance) of 4.2 × 10 ⁻⁴ Ω · cm. For this reason, the uniformity of the composition of the sputtered film was reduced although it was high density.

The oxide sintered body of the present invention is useful as a sputtering target because of its high mechanical strength, high relative density, low bulk resistance, and uniform composition.

Claims

An oxide sintered body containing In, Ga, and Zn, wherein L * in the L * a * b * color system is 35 or less.
The oxide sintered body according to claim 1, wherein a * in the L * a * b * color system is -0.6 or less.
The oxide sintered body according to claim 1 or 2, wherein the Vickers hardness is 400 or more.
The oxide sintered body according to any one of claims 1 to 3, wherein the bending strength is 90 MPa or more.
The oxide sintered body according to any one of claims 1 to 4, wherein the relative density is 99.5% or more.
The oxide sintered body according to any one of claims 1 to 5, wherein a bulk resistance value is less than 1.0 × 10 -3 Ω · cm.
The oxide sintered body according to any one of claims 1 to 6, wherein a single phase ratio is 97.5% or more.
The oxide sintered body according to any one of claims 1 to 7, wherein the crystal grain size is 9 µm or less.
An oxide sintered body containing In, Ga and Zn, having a Vickers hardness of 450 or more, a relative density of more than 97%, and a bulk resistance value of less than 1.0 × 10 −3 Ω · cm Sintered product.
An oxide sintered body containing In, Ga, and Zn, having a bending strength of 130 MPa or more, a relative density of over 97%, and a bulk resistance value of less than 1.0 × 10 −3 Ω · cm. Oxide sintered body.
The oxide sintered body according to claim 10, having a Vickers hardness of 450 or more.
The oxide sintered body according to any one of claims 9 to 11, wherein L * in the L * a * b * color system is 35 or less.
The oxide sintered body according to any one of claims 9 to 12, wherein a * in the L * a * b * color system is -0.6 or less.
The oxide sintered body according to any one of claims 9 to 13, having a relative density of 99.5% or more.
The oxide sintered body according to any one of claims 9 to 14, wherein a single phase ratio is 97.5% or more.
The oxide sintered body according to any one of claims 9 to 15, wherein the crystal grain size is 4.5 µm or less.
A sputtering target comprising the oxide sintered body according to any one of claims 1 to 16.