JP7359836B2 - Oxide sintered body, sputtering target, and method for producing sputtering target - Google Patents

Description

The present invention relates to an oxide sintered body, a sputtering target, and a method for manufacturing a sputtering target.

Conventionally, in display devices such as liquid crystal displays or organic EL displays that are driven by thin film transistors (hereinafter referred to as "TFTs"), amorphous silicon films or crystalline silicon films have been mainly used for the channel layer of the TFTs. Ta.
On the other hand, in recent years, with the demand for higher definition displays, oxide semiconductors have been attracting attention as materials used for channel layers of TFTs.

Among oxide semiconductors, an amorphous oxide semiconductor (In-Ga-Zn-O, hereinafter abbreviated as "IGZO") consisting of indium, gallium, zinc, and oxygen is particularly preferred because it has high carrier mobility. It is used. However, since IGZO uses In and Ga as raw materials, it has the disadvantage of high raw material cost.

From the viewpoint of reducing raw material costs, Zn-Sn-O (hereinafter abbreviated as "ZTO") or In-Sn-Zn-O (hereinafter abbreviated as "ITZO") in which Sn is added instead of Ga in IGZO is used. ) has been proposed.
Since ITZO exhibits extremely high mobility compared to IGZO, it is expected to be a next-generation oxide semiconductor material that is advantageous for downsizing TFTs and narrowing the frame of panels.

However, since ITZO has a large coefficient of thermal expansion and a low thermal conductivity, there is a problem that cracks are likely to occur due to thermal stress during bonding to a backing plate such as Cu or Ti and during sputtering.
Recent research has reported that reliability, which is the biggest issue with oxide semiconductor materials, can be improved by making the film denser.
High-power film formation is effective for making the film dense. However, in large-scale mass production equipment, cracking at the end portion of the target where plasma is concentrated becomes a problem, and targets made of ITZO-based materials tend to be particularly prone to cracking.

For example, Non-Patent Document 1 describes that in ceramics, Vickers hardness and tensile strength are in a proportional relationship.

Patent Document 1 discloses a mixture of zinc oxide, tin oxide, and an oxide of at least one metal (M metal) selected from the group consisting of Al, Hf, Ni, Si, Ga, In, and Ta. and an oxide sintered body obtained by sintering, the oxide sintered body having a Vickers hardness of 400 Hv or more. Patent Document 1 describes that even if a film is formed using a DC sputtering method using such an oxide sintered body, nodules are hardly generated and it is possible to stably discharge for a long time. .

Japanese Patent Application Publication No. 2012-180247

Journal of the Ceramic Society of Japan, 104, [7], 654-658 (1996)

Patent Document 1 describes that the Vickers hardness of a sputtering target containing an oxide sintered body is defined within a predetermined range. This is a value obtained by measuring the position of the surface of a cut surface cut at (t: thickness). Therefore, Patent Document 1 does not describe the Vickers hardness of the surface of the oxide sintered body.
In recent years, there has been a demand for a target with improved crack resistance during sputtering, and Patent Document 1 states that it is speculated that the generation of nodules can be suppressed by controlling the hardness of the oxide sintered body. However, there is no description of a method for improving crack resistance. Further, although Patent Document 1 states that the sintering conditions and subsequent heat treatment conditions are appropriately controlled in order to control the hardness of the oxide sintered body, the conditions described in Patent Document 1 are , it is difficult to improve crack resistance.

An object of the present invention is to provide an oxide sintered body and a sputtering target with improved crack resistance, and a method for manufacturing the sputtering target.

[1A]. An oxide sintered body, wherein the average Vickers hardness of the surface of the oxide sintered body is more than 500 Hv and less than 900 Hv.

[2A]. A sputtering target comprising the oxide sintered body according to [1A].

[1]. A sputtering target comprising an oxide sintered body, wherein the average Vickers hardness of the surface of the oxide sintered body is more than 500 Hv and less than 900 Hv.

[2]. The sputtering target according to [1] or [2A], wherein the oxide sintered body contains an indium element, a tin element, and a zinc element.

[3]. In the sputtering target according to [2], the oxide sintered body further includes element X, and element X includes element germanium, silicon element, yttrium element, zirconium element, aluminum element, magnesium element, ytterbium element, and A sputtering target that is at least one element selected from the group consisting of the gallium element.

[4]. The sputtering target according to [2] or [3], wherein the oxide sintered body satisfies the range of atomic composition ratios represented by the following formulas (1), (2), and (3).
0.40≦Zn/(In+Sn+Zn)≦0.80...(1)
0.15≦Sn/(Sn+Zn)≦0.40 (2)
0.10≦In/(In+Sn+Zn)≦0.35 (3)

[5]. In the sputtering target according to any one of [2] to [4],
The oxide sintered body is a sputtering target including a hexagonal layered compound represented by In ₂ O ₃ (ZnO) m [m=2 to 7] and a spinel structure compound represented by Zn ₂ SnO ₄ .

[5A]. The oxide sintered body is a hexagonal layered compound represented by In ₂ O ₃ (ZnO) m [m=2-7] and Zn _2-x Sn _1-y In _x+y O ₄ [0≦x<2, 0≦y<1], including a spinel structure compound represented by
The sputtering target according to any one of [2] to [4]

[6]. A method for manufacturing a sputtering target for manufacturing the sputtering target according to any one of [1] to [5], [2A] and [5A],
Granulating the raw material for the oxide sintered body to obtain raw material granulated powder having a particle size of 25 μm or more and 150 μm or less;
filling the raw material granulated powder into a mold and molding the raw material granulated powder filled in the mold to obtain a molded body;
Sintering the molded body at a temperature of 1310°C or higher and 1440°C or lower,
A method of manufacturing a sputtering target.

[7]. The method for producing a sputtering target according to [6], wherein the raw material granulated powder has a particle size of 25 μm or more and 75 μm or less.

According to one aspect of the present invention, it is possible to provide an oxide sintered body and a sputtering target with improved crack resistance.
According to one aspect of the present invention, a method for manufacturing a sputtering target according to one aspect of the present invention can be provided.

FIG. 2 is a perspective view showing the shape of a target according to an embodiment of the present invention. FIG. 2 is a perspective view showing the shape of a target according to an embodiment of the present invention. FIG. 2 is a perspective view showing the shape of a target according to an embodiment of the present invention. FIG. 2 is a perspective view showing the shape of a target according to an embodiment of the present invention. It is a SEM observation image of raw material granulated powder prepared in an example. It is an XRD chart of an oxide sintered compact concerning an example.

Cracks in sputtering targets occur starting from weak parts of the target.
Therefore, as a measure to improve crack resistance, the present inventor considered reducing the variation in strength within the plane of the sputtering target, and in particular, improving the minimum strength.
As a result of intensive study on the manufacturing conditions of sputtering targets, the inventors of the present invention improved the minimum value of Vickers hardness on the sputtering surface of the oxide sintered body by optimizing the particle size and sintering temperature of the raw material granulated powder. However, we found that the average value improved.
We also found that there is an optimal range for the average value of Vickers hardness in oxide sintered bodies, and that if the Vickers hardness is too high, microcracks will occur during the target grinding process and crack resistance will decrease.
The present inventor invented the present invention based on these findings.

Hereinafter, embodiments will be described with reference to the drawings and the like. However, those skilled in the art will readily understand that the embodiments can be implemented in many different ways and that the form and details can be changed in various ways without departing from the spirit and scope of the invention. . Therefore, the present invention should not be interpreted as being limited to the contents described in the following embodiments.

In the drawings, the dimensions, layer thicknesses, and regions may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale. Note that the drawings schematically show ideal examples, and the present invention is not limited to the shapes and values shown in the drawings.

It should be noted that the ordinal numbers "first," "second," and "third" used in this specification are added to avoid confusion among the constituent elements, and are not intended to be numerically limited. .

In this specification and the like, the term "film" or "thin film" and the term "layer" may be interchanged with each other in some cases.

In the sintered body and oxide semiconductor thin film in this specification and the like, the term "compound" and the term "crystalline phase" can be interchanged with each other in some cases.

In this specification, the "oxide sintered body" may be simply referred to as the "sintered body".
In this specification, a "sputtering target" may be simply referred to as a "target."

[Sputtering target]
A sputtering target according to an embodiment of the present invention (hereinafter sometimes simply referred to as a sputtering target according to the present embodiment) includes an oxide sintered body.
The sputtering target according to the present embodiment is obtained, for example, by cutting and polishing a bulk of an oxide sintered body into a shape suitable as a sputtering target.
Further, the sputtering target according to the present embodiment can also be obtained by bonding a sputtering target material obtained by grinding and polishing a bulk of an oxide sintered body to a backing plate.
Further, as the sputtering target of this embodiment according to another aspect, a target made only of an oxide sintered body can also be mentioned.

The shape of the oxide sintered body is not particularly limited.
A plate-shaped oxide sintered body as shown by reference numeral 1 in FIG. 1 may be used.
A cylindrical oxide sintered body as shown by the reference numeral 1A in FIG. 2 may be used.
When the oxide sintered body is plate-shaped, the planar shape of the oxide sintered body may be rectangular as shown by reference numeral 1 in FIG. 1, or circular as shown by reference numeral 1B in FIG. 3.

The oxide sintered body may be integrally molded or may be divided into a plurality of pieces as shown in FIG. Each of the plurality of divided oxide sintered bodies (symbol 1C) may be fixed to the backing plate 3. A sputtering target obtained by bonding a plurality of oxide sintered bodies 1C to one backing plate 3 in this way is sometimes referred to as a multi-segmented sputtering target. The backing plate 3 is a member for holding and cooling the oxide sintered body. The material of the backing plate 3 is not particularly limited. As the material for the backing plate 3, at least one material selected from the group consisting of Cu, Ti, SUS, etc. is used, for example.

(Vickers hardness)
In the target according to this embodiment, the average Vickers hardness (H _av ) of the surface of the oxide sintered body is more than 500 Hv and less than 900 Hv. In this specification, Vickers hardness is measured using a Hardness Tester (AKASHI MVK-E3) in accordance with JIS Z 2244:2009. The measurement points are data collected every 30 mm from one end along the center line of the oxide sintered body (142 x 305 mm size), and the average value of the collected data is calculated from the Vickers surface of the oxide sintered body. Let it be the average value of hardness (H _av ).
When the average Vickers hardness (H _av ) of the surface of the oxide sintered body exceeds 500 Hv, there are few parts of the sputtering surface of the target where the strength is weak. Therefore, the crack resistance of the sputtering target according to this embodiment is improved.
If the Vickers hardness is too high, microcracks may occur during the grinding process. However, in this embodiment, since the average Vickers hardness (H _av ) of the surface of the oxide sintered body is less than 900 Hv, it is possible to suppress the generation of microcracks during the target grinding process. As a result, deterioration in crack resistance caused by microcracks can also be suppressed.
The average Vickers hardness (H _av ) of the surface of the oxide sintered body is preferably 520 Hv or more and 850 Hv or less, more preferably 600 Hv or more and 750 Hv or less.

It is preferable that the minimum value of Vickers hardness (H _min ) of the surface of the oxide sintered body exceeds 500 Hv, and more preferably 600 Hv or more. When the minimum value of Vickers hardness (H _min ) exceeds 500 Hv, there are fewer weak parts on the sputtering surface of the target, and crack resistance is further improved. In addition, in this specification, the minimum value of Vickers hardness (H _min ) is the lowest value among the Vickers hardness values of the 10 locations measured by measuring the Vickers hardness at 10 locations on the surface of the oxide sintered body. be.

The maximum Vickers hardness (H _max ) of the surface of the oxide sintered body is preferably less than 900 Hv, more preferably 850 Hv or less. When the maximum value of Vickers hardness (H _max ) is less than 900 Hv, the generation of microcracks during the target grinding process is further suppressed, and as a result, crack resistance is further improved. In addition, in this specification, the maximum value of Vickers hardness (H _max ) is the largest value among the Vickers hardness values of the 10 locations measured by measuring the Vickers hardness at 10 locations on the surface of the oxide sintered body. be.

(Composition of oxide sintered body)
The oxide sintered body according to this embodiment preferably contains an indium element (In), a tin element (Sn), and a zinc element (Zn).
The oxide sintered body according to the present embodiment may contain metal elements other than In, Sn, and Zn within a range that does not impair the effects of the present invention, or may contain substantially In, Sn, and Zn. It may contain only In, Sn, and Zn. Here, "substantially" means that 95% by mass or more and 100% by mass or less (preferably 98% by mass or more and 100% by mass or less) of the metal elements in the oxide sintered body are indium element (In), tin element (Sn), etc. ) and zinc element (Zn). The oxide sintered body according to the present embodiment may contain inevitable impurities in addition to In, Sn, Zn, and oxygen element (O) within a range that does not impair the effects of the present invention. The unavoidable impurities herein refer to elements that are not intentionally added and that are mixed into raw materials or during the manufacturing process.

It is also preferable that the oxide sintered body according to this embodiment contains an indium element (In), a tin element (Sn), a zinc element (Zn), and an X element.
The oxide sintered body according to the present embodiment may contain metal elements other than In, Sn, Zn, and X element within a range that does not impair the effects of the present invention, or may contain substantially In, It may contain only Sn, Zn and the X element, or it may consist only of In, Sn, Zn and the X element. Here, "substantially" means that 95% by mass or more and 100% by mass or less (preferably 98% by mass or more and 100% by mass or less) of the metal elements of the oxide sintered body are In, Sn, Zn, and X elements. It means that. The oxide sintered body according to the present embodiment may contain inevitable impurities in addition to In, Sn, Zn, X element, and oxygen element (O) within a range that does not impair the effects of the present invention. The unavoidable impurities herein refer to elements that are not intentionally added and that are mixed into raw materials or during the manufacturing process.
Element X is germanium element (Ge), silicon element (Si), yttrium element (Y), zirconium element (Zr), aluminum element (Al), magnesium element (Mg), ytterbium element (Yb), and gallium element (Ga ) is at least one element selected from the group consisting of:

Examples of unavoidable impurities include alkali metals (Li, Na, K, Rb, etc.), alkaline earth metals (Ca, Sr, Ba, etc.), hydrogen (H) element, boron (B) element, carbon (C) element, nitrogen (N) element, fluorine (F) element, and chlorine (Cl) element.

Impurity concentration can be measured by ICP or SIMS.

<Measurement of impurity concentration (H, C, N, F, Si, Cl)>
The impurity concentration (H, C, N, F, Si, Cl) in the obtained sintered body was determined by SIMS analysis using a sector type dynamic secondary ion mass spectrometer (IMS 7f-Auto, manufactured by AMETEK CAMECA). It can be quantitatively evaluated by
Specifically, first, sputtering is performed using primary ions Cs ⁺ at an accelerating voltage of 14.5 kV to a depth of 20 μm from the surface of the sintered body to be measured. After that, impurities (H, C, N, F, Si, Cl) are sputtered with primary ions on a raster of 100 μm□ (size of 100 μm x 100 μm), measurement area of 30 μm□ (size of 30 μm x 30 μm), and depth of 1 μm. Integrate the mass spectral intensity of .

Furthermore, in order to calculate the absolute value of the impurity concentration from the mass spectrum, each impurity is injected into the sintered body by ion implantation at a controlled dose to prepare a standard sample with a known impurity concentration. Mass spectral intensities of impurities (H, C, N, F, Si, Cl) are obtained for the standard sample by SIMS analysis, and the relational expression between the absolute value of the impurity concentration and the mass spectral intensity is used as a calibration curve.
Finally, the impurity concentration of the measurement target is calculated using the mass spectrum intensity of the sintered body to be measured and the calibration curve, and this is taken as the absolute value of the impurity concentration (atom·cm ⁻³ ).

<Measurement of impurity concentration (B, Na)>
The impurity concentration (B, Na) of the obtained sintered body can also be quantitatively evaluated by SIMS analysis using a sector type dynamic secondary ion mass spectrometer (IMS 7f-Auto, manufactured by AMETEK CAMECA). Measurement was carried out in the same manner as the measurement of H, C, N, F, Si, and Cl, except that the primary ion was O ₂ ⁺ , the acceleration voltage of the primary ion was 5.5 kV, and the mass spectrum of each impurity was measured. The absolute value (atom·cm ⁻³ ) of the target impurity concentration can be obtained.

In the oxide sintered body according to the present embodiment, it is more preferable that the atomic composition ratio of each element satisfies at least one of the following formulas (1) to (3).
0.40≦Zn/(In+Sn+Zn)≦0.80...(1)
0.15≦Sn/(Sn+Zn)≦0.40 (2)
0.10≦In/(In+Sn+Zn)≦0.35 (3)

In formulas (1) to (3), In, Zn, and Sn represent the contents of indium element, zinc element, and tin element in the oxide sintered body, respectively.

If Zn/(In+Sn+Zn) is 0.40 or more, a spinel phase is likely to occur in the oxide sintered body, and semiconductor properties can be easily obtained.
When Zn/(In+Sn+Zn) is 0.80 or less, it is possible to suppress a decrease in strength due to abnormal grain growth of the spinel phase in the oxide sintered body. Moreover, if Zn/(In+Sn+Zn) is 0.80 or less, a decrease in the mobility of the oxide semiconductor thin film can be suppressed.
Zn/(In+Sn+Zn) is more preferably 0.50 or more and 0.70 or less.

If Sn/(Sn+Zn) is 0.15 or more, it is possible to suppress a decrease in strength due to abnormal grain growth of the spinel phase in the oxide sintered body.
When Sn/(Sn+Zn) is 0.40 or less, agglomeration of tin oxide, which causes abnormal discharge during sputtering, can be suppressed in the oxide sintered body. Further, when Sn/(Sn+Zn) is 0.40 or less, the oxide semiconductor thin film formed using a sputtering target can be easily etched with a weak acid such as oxalic acid. When Sn/(Sn+Zn) is 0.15 or more, it is possible to prevent the etching rate from becoming too high and to facilitate etching control.
Sn/(Sn+Zn) is more preferably 0.15 or more and 0.35 or less.

If In/(In+Sn+Zn) is 0.10 or more, the bulk resistance of the resulting sputtering target can be lowered. Moreover, when In/(In+Sn+Zn) is 0.10 or more, it is possible to suppress the mobility of the oxide semiconductor thin film from becoming extremely low.
If In/(In+Sn+Zn) is 0.35 or less, the film can be prevented from becoming a conductor during sputtering film formation, and it becomes easy to obtain properties as a semiconductor.
In/(In+Sn+Zn) is preferably 0.10 or more and 0.30 or less.

When the oxide sintered body according to the present embodiment contains element X, the atomic ratio of each element preferably satisfies the following formula (1X).
0.001≦X/(In+Sn+Zn+X)≦0.05...(1X)
(In formula (1X), In, Zn, Sn, and X represent the contents of indium element, zinc element, tin element, and X element in the oxide sintered body, respectively.)

Within the range of the above formula (1X), the crack resistance of the oxide sintered body according to this embodiment can be sufficiently increased.
The X element is preferably at least one selected from the group consisting of silicon element (Si), aluminum element (Al), magnesium element (Mg), ytterbium element (Yb), and gallium element (Ga).
More preferably, the X element is at least one selected from the group consisting of silicon element (Si), aluminum element (Al), and gallium element (Ga).
Aluminum element (Al) and gallium element (Ga) are more preferable because the composition of the oxide as a raw material is stable and the effect of improving crack resistance is high.

If X/(In+Sn+Zn+X) is 0.001 or more, a decrease in strength of the sputtering target can be suppressed. If X/(In + Sn + Zn + become. Furthermore, if X/(In+Sn+Zn+X) is 0.05 or less, a decrease in TFT characteristics, particularly mobility, can be suppressed.
X/(In+Sn+Zn+X) is preferably 0.001 or more and 0.05 or less, more preferably 0.003 or more and 0.03 or less, and 0.005 or more and 0.01 or less. is more preferable, and even more preferably 0.005 or more and less than 0.01.
When the oxide sintered body according to this embodiment contains the X element, only one type of X element may be used, or two or more types of X element may be used. When two or more types of X elements are included, X in formula (1X) is the sum of the atomic ratios of the X elements.
The form of the X element in the oxide sintered body is not particularly defined. Examples of the existing form of element X in the oxide sintered body include a form in which it exists as an oxide, a form in which it exists as a solid solution, and a form in which it segregates at grain boundaries.

The atomic ratio of each metal element in the oxide sintered body can be controlled by the blending amount of the raw materials. Further, the atomic ratio of each element can be determined by quantitatively analyzing the contained elements using an inductively coupled plasma emission spectrometer (ICP-AES).

The oxide sintered body according to the present embodiment preferably contains a spinel structure compound represented by Zn _2-x Sn _1-y In _x+y O ₄ [0≦x<2, 0≦y<1] . In this specification, a spinel structure compound may be referred to as a spinel compound. In Zn _2-x Sn _1-y In _x+y O ₄ , when x is 0 and y is 0, it is represented by Zn ₂ SnO ₄ .

The oxide sintered body according to this embodiment preferably contains a hexagonal layered compound represented by In ₂ O ₃ (ZnO) _m . In the present embodiment, In ₂ O ₃ (ZnO) _m is an integer of 2 to 7, preferably 3 to 5. When m is 2 or more, the compound has a hexagonal layered structure. If m is 7 or less, the bulk resistance of the oxide sintered body will be low.

The oxide sintered body according to the present embodiment is a hexagonal layered compound represented by In ₂ O ₃ (ZnO) _m [m=2 to 7] and Zn _2-x Sn _1-y In _x+y O ₄ [0≦ It is more preferable to contain a spinel structure compound represented by x<2,0≦y<1].

A hexagonal layered compound consisting of indium oxide and zinc oxide is a compound that exhibits an X-ray diffraction pattern that is assigned to a hexagonal layered compound when measured by an X-ray diffraction method. The hexagonal layered compound contained in the oxide sintered body is a compound represented by In ₂ O ₃ (ZnO) _m .

The oxide sintered body according to the present embodiment is a spinel structure compound represented by Zn _2-x Sn _1-y In _x+y O ₄ [0≦x<2, 0≦y<1] and In ₂ O ₃ . It may contain the bixbite structure compound shown below.

(bulk resistance)
When the oxide sintered body according to the present embodiment contains the X element, the bulk resistance of the sputtering target can be made sufficiently low as long as the content ratio of the X element is within the range of the above formula (1X).

The bulk resistance of the sputtering target according to the present embodiment is preferably 50 mΩcm or less, more preferably 25 mΩcm or less, even more preferably 10 mΩcm or less, even more preferably 5 mΩcm or less, and even more preferably 3 mΩcm or less. It is particularly preferable that If the bulk resistance is 50 mΩcm or less, stable film formation can be performed by DC sputtering.
The bulk resistance value can be measured using a known resistivity meter based on the four-point probe method (JIS R 1637:1998). The number of measurement points is approximately nine, and it is preferable that the average value of the measured values at the nine points is taken as the bulk resistance value.
When the planar shape of the oxide sintered body is a rectangle, the measurement points are preferably 9, which are the center points of each of the 3 x 3 squares that the surface is divided into.
In addition, when the planar shape of the oxide sintered body is circular, it is preferable that the square inscribed in the circle is divided into nine 3×3 parts, and the center points of each square are set at nine locations.

(Average grain size)
The average crystal grain size of the oxide sintered body according to this embodiment is preferably 10 μm or less, more preferably 8 μm or less, from the viewpoint of preventing abnormal discharge and manufacturing ease.
If the average crystal grain size is 10 μm or less, abnormal discharge due to grain boundaries can be prevented. Although the lower limit of the average crystal grain size of the oxide sintered body is not particularly defined, it is preferably 1 μm or more from the viewpoint of ease of manufacture.
The average crystal grain size can be adjusted by selecting raw materials and changing manufacturing conditions. Specifically, it is preferable to use a raw material with a small average particle size, and it is more preferable to use a raw material with an average particle size of 1 μm or less. Furthermore, during sintering, the higher the sintering temperature or the longer the sintering time, the larger the average crystal grain size tends to be.

The average grain size can be measured as follows.
If the surface of the oxide sintered body is polished and the planar shape is a square, the surface is divided into 16 equal areas, and the center points of each square are divided into 16 areas at a magnification of 1000 times (80 μm x 125 μm). The particle size observed at is measured, the average value of the particle size of the particles within the frame at 16 locations is determined, and finally the average value of the measured values at 16 locations is defined as the average crystal grain size.
When the surface of the oxide sintered body is polished and the planar shape is circular, the square inscribed in the circle is divided into 16 equal areas, and at the 16 center points of each square, a magnification of 1000 times (80 μm x 125 μm) is applied. The particle size of the particles observed within the frame is measured, and the average value of the particle sizes of the particles within the frame at 16 locations is determined.
For grains with an aspect ratio of less than 2, the grain size is measured based on JIS R 1670:2006, with the grain size of the crystal grains as equivalent circle diameter. Specifically, as a procedure for measuring the equivalent circle diameter, a circular ruler is applied to the grain to be measured in the microstructure photograph, and the diameter corresponding to the area of the grain to be measured is read. For particles with an aspect ratio of 2 or more, the average value of the longest diameter and the shortest diameter is taken as the particle size of the particle. Crystal grains can be observed using a scanning electron microscope (SEM). The hexagonal layered compound, spinel compound, and bixbite structure compound can be confirmed by the method described in the Examples below.

When the oxide sintered body according to the present embodiment includes a hexagonal layered compound and a spinel compound, the difference between the average crystal grain size of the hexagonal layered compound and the average crystal grain size of the spinel compound is 1 μm or less. It is preferable that there be. By setting the average crystal grain size within such a range, the strength of the oxide sintered body can be improved.
It is more preferable that the average crystal grain size of the oxide sintered body according to this embodiment is 10 μm or less, and the difference between the average crystal grain size of the hexagonal layered compound and the average crystal grain size of the spinel compound is 1 μm or less. .

Further, when the oxide sintered body according to the present embodiment includes a bixbite structure compound and a spinel compound, the difference between the average crystal grain size of the bixbite structure compound and the average crystal grain size of the spinel compound is 1 μm. It is preferable that it is below. By setting the average crystal grain size within such a range, the strength of the oxide sintered body can be improved.
It is more preferable that the average crystal grain size of the oxide sintered body according to this embodiment is 10 μm or less, and the difference between the average crystal grain size of the bixbite structure compound and the average crystal grain size of the spinel compound is 1 μm or less. .

(relative density)
The relative density of the oxide sintered body according to this embodiment is preferably 95% or more, more preferably 96% or more.
When the relative density of the oxide sintered body according to this embodiment is 95% or more, the sputtering target according to this embodiment has high mechanical strength and excellent conductivity. Therefore, the stability of plasma discharge can be further improved when sputtering is performed by attaching the sputtering target according to this embodiment to an RF magnetron sputtering device or a DC magnetron sputtering device. The relative density of an oxide sintered body is calculated from the unique density of each oxide in the sintered body and their composition ratio, and the actually measured density of the oxide sintered body is expressed as a percentage of the theoretical density. It is something that The relative density of the oxide sintered body is, for example, the theoretical density calculated from the unique densities of indium oxide, zinc oxide, tin oxide, and the oxides of element X contained as necessary and their composition ratios. The actually measured density of the oxide sintered body is shown in percentage.

The relative density of the oxide sintered body can be measured based on the Archimedes method. Specifically, the relative density (unit: %) is calculated by dividing the air weight of the oxide sintered body by the volume (= weight of the sintered body in water/specific gravity of water at the measurement temperature), and calculating the following formula (Equation 5). The value is a percentage of the theoretical density ρ (g/cm ³ ) based on
Relative density = {(air weight/volume of oxide sintered body)/theoretical density ρ}×100

ρ=(C ₁ /100/ρ ₁ +C ₂ /100/ρ ₂ ...+C _n /100/ρ _n ) ^-1 ...(Math. 5)
In addition, in the formula (Equation 5), C ₁ to C _n each represent the content (mass%) of the oxide sintered body or the constituent material of the oxide sintered body, and ρ ₁ to ρ _n are The density (g/cm ³ ) of each constituent material corresponding to C ₁ to C _n is shown.
In addition, since the density and specific gravity are almost the same, the density of each constituent substance is determined using the value of the specific gravity of the oxide listed in the Chemical Handbook, Basic Edition I, edited by the Chemical Society of Japan, revised 2nd edition (Maruzen Co., Ltd.). be able to.

[Method for manufacturing oxide sintered body]
The method for producing an oxide sintered body according to the present embodiment includes a mixing/pulverizing process, a granulating process, a molding process, and a sintering process. The method for producing an oxide sintered body may include other steps. Other steps include an annealing step.
Hereinafter, each step will be specifically explained using the case of manufacturing an ITZO-based oxide sintered body as an example.

The oxide sintered body according to this embodiment includes a mixing/pulverizing process of mixing and pulverizing an indium raw material, a zinc raw material, a tin raw material, and an X element raw material, a granulation process of granulating the raw material mixture, a molding process of molding, and a molding process. It can be manufactured through a sintering process in which the object is sintered and an annealing process in which the sintered body is annealed as necessary.

(1) Mixing/pulverizing process The mixing/pulverizing process is a process of mixing and pulverizing the raw materials for the oxide sintered body to obtain a raw material mixture. For example, the raw material mixture is preferably in powder form.
In the mixing/pulverizing process, first, raw materials for the oxide sintered body are prepared.

The raw materials used to produce the oxide sintered body containing In, Zn, and Sn are as follows.
The indium raw material (In raw material) is not particularly limited as long as it is a compound or metal containing In.
The zinc raw material (Zn raw material) is not particularly limited as long as it is a compound or metal containing Zn.
The tin raw material (Sn raw material) is not particularly limited as long as it is a compound or metal containing Sn.

The raw materials for producing the oxide sintered body containing the X element are as follows.
The raw material for element X is also not particularly limited as long as it is a compound or metal containing element X.

The In raw material, Zn raw material, Sn raw material, and X element raw material are preferably oxides.
It is preferable that raw materials such as indium oxide, zinc oxide, tin oxide, and X element oxide have high purity. The purity of the raw material for the oxide sintered body is preferably 99% by mass or more, more preferably 99.9% by mass or more, and even more preferably 99.99% by mass or more. When a high-purity raw material is used, a sintered body with a dense structure can be obtained, and a sputtering target made of the sintered body has a low volume resistivity.

The average particle size of the primary particles of the metal oxide as a raw material is preferably 0.01 μm or more and 10 μm or less, more preferably 0.05 μm or more and 5 μm or less, and 0.1 μm or more and 5 μm or less. It is more preferable that
If the average particle size of the primary particles of the metal oxide as a raw material is 0.01 μm or more, it will be difficult to aggregate, and if the average particle size is 10 μm or less, the mixing property will be sufficient and a sintered body with a dense structure will be obtained. is obtained. The average particle size is measured using a laser diffraction particle size distribution analyzer SALD-300V (manufactured by Shimadzu Corporation) using the median diameter D50.

The raw materials for the oxide sintered body are mixed and pulverized using a bead mill or the like, with the addition of a dispersant to break up the agglomeration and a thickener to adjust the viscosity to a level suitable for granulation in a spray dryer. Examples of the dispersant include ammonia neutralized acrylic acid methacrylic acid copolymer, and examples of the thickener include polyvinyl alcohol.

(2) Calcination treatment step The raw material mixture obtained in the mixing/pulverization step may be granulated immediately, or may be subjected to calcination treatment before granulation. In the calcination treatment, the raw material mixture is usually fired at a temperature of 700° C. or higher and 900° C. or lower for 1 hour or more and 5 hours or less.

(3) Granulation process A raw material mixture that has not been calcined or a raw material mixture that has been calcined can be granulated to improve fluidity and filling properties in the molding process described in (4) below. .
In this specification, the process of granulating the raw material for the oxide sintered body to obtain raw material granulated powder may be referred to as a granulation process.
The granulation process can be performed using a spray dryer or the like. The granulated powder obtained in the granulation process is preferably perfectly spherical in order to uniformly fill the mold in the molding process.
The granulation conditions are appropriately selected by adjusting the concentration of the raw material slurry to be introduced, the rotation speed of the spray dryer, the hot air temperature, etc.
When preparing a slurry solution, if a raw material mixture that has not been calcined is used, the slurry solution obtained in the mixing/pulverizing process is used as is, and if a raw material mixture that has been calcined is used, the slurry solution is mixed again.・It is used after being prepared into a slurry solution through a pulverization process.

In the method for producing an oxide sintered body according to the present embodiment, the particle size of the raw material granulated powder formed by the granulation process is controlled within the range of 25 μm or more and 150 μm or less.
If the particle size of the raw material granulated powder is 25 μm or more, the slipperiness of the raw material granulated powder on the surface of the mold used in the molding process (4) below will improve, and the raw material granulated powder will be sufficiently filled in the mold. can be filled.
When the particle size of the raw material granulated powder is 150 μm or less, it is possible to prevent the filling rate in the mold from becoming low due to the particle size being too large.
The particle size of the raw material granulated powder is preferably 25 μm or more and 75 μm or less.

The method for obtaining raw material granulated powder having a particle size within a predetermined range is not particularly limited. For example, a method may be used in which a raw material mixture (raw material granulated powder) subjected to granulation treatment is passed through a sieve to select raw material granulated powder belonging to a desired particle size range. The sieve used in this method is preferably a sieve having openings large enough to allow the raw material granulated powder of a desired particle size to pass through. It is preferable to use a first sieve for sorting the raw material granulated powder based on the lower limit of the particle size range and a second sieve for sorting the raw material granulated powder based on the upper limit of the particle size range. For example, when controlling the particle size of raw material granulated powder within the range of 25 μm or more and 150 μm or less, first, the raw material granulated powder of less than 25 μm can pass through, and the raw material granulated powder of 25 μm or more does not pass. Using a sieve (first sieve) having openings, raw material granulated powder having a particle size of 25 μm or more is sorted. Next, the raw material granulated powder after sorting is passed through a sieve (second sieve) having an opening size that allows raw material granulated powder of 150 μm or less to pass through, but does not allow raw material granulated powder of more than 150 μm to pass through. Then, raw material granulated powder having a particle diameter of 25 μm or more and 150 μm or less is selected. The second sieve may be used first, and then the first sieve may be used.
The method for controlling the particle size range of the raw material granulated powder is not limited to the method using a sieve as described above, and the raw material granulated powder to be subjected to the forming process in (4) below is within the range of 25 μm or more and 150 μm or less. That's fine.

In addition, in the raw material mixture subjected to the calcining treatment, the particles are bonded to each other, so when performing the granulation treatment, it is preferable to perform the pulverization treatment before the granulation treatment.

(4) Molding process In this specification, the process of filling the raw material granulated powder obtained in the granulation process into a mold and molding the raw material granulated powder filled in the mold to obtain a molded body is described. Sometimes called a molding process.
Examples of the molding method in the molding step include die press molding.
When obtaining a sintered body with high sintering density as a sputtering target, after preforming by mold press molding etc. in the molding process, it is further consolidated by cold isostatic pressing (CIP) molding etc. It is preferable to do so.

The particle size of the raw material granulated powder is preferably 25 μm or more and 150 μm or less, more preferably 25 μm or more and 75 μm or less.
If the particle size of the raw material granulated powder is 25 μm or more and 150 μm or less, the raw material granulated powder can be sufficiently filled into the mold used in the molding process, so that variations in density in the molded product can also be reduced.

(5) Sintering process In this specification, the process of sintering the molded body obtained in the molding process within a predetermined temperature range may be referred to as a sintering process.
In the sintering step, a commonly used sintering method such as pressureless sintering, hot press sintering, or hot isostatic pressing (HIP) sintering can be used.

The sintering temperature is preferably 1310°C or higher and 1440°C or lower, more preferably 1320°C or higher and 1430°C or lower.
When the sintering temperature is 1310° C. or more and 1440° C. or less, the average value of Vickers hardness (H _av ) of the surface of the oxide sintered body can be easily controlled within the above range. That is, by producing a molded body using raw material granulated powder having a particle size within a predetermined range obtained in the granulation process and sintering this molded body at a predetermined temperature, the strength of the oxide sintered body can be increased. It is possible to reduce the variation in the hardness and prevent the Vickers hardness from becoming too large.
If the sintering temperature is 1310° C. or higher, sufficient sintering density can be obtained and the bulk resistance of the sputtering target can also be lowered.
If the sintering temperature is 1440° C. or lower, sublimation of zinc oxide during sintering can be suppressed.

In the sintering step, the rate of temperature increase from room temperature to the sintering temperature is preferably 0.1° C./min or more and 3° C./min or less.
Further, in the temperature raising process, the temperature may be maintained at 700° C. or higher and 800° C. or lower for 1 hour or more and 10 hours or less, and after being held at a predetermined temperature for a predetermined time, the temperature may be raised to the sintering temperature.

The sintering time varies depending on the sintering temperature, but is preferably 1 hour or more and 50 hours or less, more preferably 2 hours or more and 30 hours or less, and 3 hours or more and 20 hours or less. More preferred.
Examples of the atmosphere during sintering include an atmosphere of air or oxygen gas, an atmosphere containing air or oxygen gas and a reducing gas, or an atmosphere containing air or oxygen gas and an inert gas. Examples of the reducing gas include hydrogen gas, methane gas, and carbon monoxide gas. Examples of the inert gas include argon gas and nitrogen gas.

(6) Annealing process In the method for manufacturing an oxide sintered body according to this embodiment, the annealing process is not essential. When performing the annealing step, the temperature is usually maintained at 700° C. or higher and 1100° C. or lower for 1 hour or more and 5 hours or less.
In the annealing step, the sintered body may be once cooled and then the temperature may be raised again for annealing, or the sintered body may be annealed when the temperature is lowered from the sintering temperature.
Examples of the atmosphere during annealing include an atmosphere of air or oxygen gas, an atmosphere containing air or oxygen gas and a reducing gas, or an atmosphere containing air or oxygen gas and an inert gas. Examples of the reducing gas include hydrogen gas, methane gas, and carbon monoxide gas. Examples of the inert gas include argon gas and nitrogen gas.

In addition, when manufacturing an oxide sintered body of a system different from the ITZO system, it can be manufactured by the same process as described above.

[Method for manufacturing sputtering target]
A sputtering target can be manufactured by cutting the oxide sintered body obtained by the above manufacturing method into an appropriate shape and polishing the surface of the oxide sintered body as necessary.
Specifically, a sputtering target material (sometimes referred to as target material) is obtained by cutting the oxide sintered body into a shape suitable for attachment to a sputtering device. A sputtering target is obtained by adhering this target material to a backing plate.

When using an oxide sintered body as a target material, the surface roughness Ra of the sintered body is preferably 0.5 μm or less. An example of a method for adjusting the surface roughness Ra of the sintered body is a method of grinding the sintered body with a surface grinder.

The surface of the sputtering target material is preferably finished with a diamond grindstone of No. 100 to 1,000, and particularly preferably finished with a diamond grindstone of No. 400 to 800. By using a diamond grindstone of No. 100 or more or No. 1,000 or less, cracking of the sputtering target material can be prevented.
It is preferable that the sputtering target material has a surface roughness Ra of 0.5 μm or less and has a ground surface without directionality. If the sputtering target material has a surface roughness Ra of 0.5 μm or less and has a ground surface with no directionality, abnormal discharge and generation of particles can be prevented.

Finally, the obtained sputtering target material is cleaned. Examples of the cleaning treatment include air blowing and running water washing. When removing foreign matter with air blow, it is possible to remove the foreign matter more effectively by using a dust collector to draw in air from the opposite side of the air blow nozzle.
In addition to the above-mentioned cleaning treatment by air blowing or running water cleaning, ultrasonic cleaning or the like may be further performed. An effective method for ultrasonic cleaning is a method in which multiple oscillations are performed at a frequency of 25 kHz or more and 300 kHz or less. For example, it is preferable to perform ultrasonic cleaning by multiplexing 12 different frequencies at 25 kHz intervals between 25 kHz and 300 kHz.

The thickness of the sputtering target material is usually 2 mm or more and 20 mm or less, preferably 3 mm or more and 12 mm or less, more preferably 4 mm or more and 9 mm or less, and even more preferably 4 mm or more and 6 mm or less. preferable.

A sputtering target can be manufactured by bonding the sputtering target material obtained through the steps and treatments described above to a backing plate. Alternatively, a plurality of sputtering target materials may be attached to one backing plate to produce substantially one sputtering target (multi-segmented sputtering target).

The sputtering target according to the present embodiment includes an oxide sintered body, and the average Vickers hardness (H _av ) of the surface of the oxide sintered body is more than 500 Hv and less than 900 Hv, so crack resistance is low. It is an improved sputtering target.

If sputtering film formation is performed using the sputtering target according to this embodiment, the crack resistance is improved, so that an oxide semiconductor thin film can be stably manufactured.

Hereinafter, the present invention will be specifically explained based on Examples. The invention is not limited to the examples.

A sputtering target made of an ITZO-based oxide sintered body was produced.

(Example 1)
First, the following powders were weighed as raw materials so that the atomic ratios were (In: 25 atomic %, Sn: 15 atomic %, Zn: 60 atomic %).
・In raw material: Indium oxide powder with a purity of 99.99% by mass
(Average particle size: 0.3μm)
・Sn raw material: tin oxide powder with a purity of 99.99% by mass
(Average particle size: 1.0μm)
・Zn raw material: Zinc oxide powder with a purity of 99.99% by mass
(Average particle size: 3.0μm)

The median diameter D50 was used as the average particle diameter of the oxide powder used as a raw material, and the average particle diameter was measured with a laser diffraction particle size distribution analyzer SALD-300V (manufactured by Shimadzu Corporation).

Next, acrylic acid methacrylic acid copolymer ammonia neutralized product (manufactured by Sanmei Kasei Co., Ltd., Banstar The mixture was mixed and pulverized for a period of time to obtain a slurry solution for granulation having a solid content concentration of 70% by mass. The obtained slurry solution was supplied to a spray dryer and granulated at a rotation speed of 12,000 rpm and a hot air temperature of 150° C. to obtain a raw material granulated powder.
The raw material granulated powder is passed through a 200-mesh sieve to remove granulated powder with a particle size of more than 75 μm, and then passed through a 500-mesh sieve to remove granulated powder with a particle size of less than 25 μm. The particle size was adjusted within the range of 25 μm or more and 75 μm or less.
FIG. 5 shows a SEM observation image of the raw material granulated powder prepared in Example 1.

Next, this raw material granulated powder was uniformly filled into a mold with an inner diameter of 300 mm x 600 mm x 9 mm, and pressure molded using a cold press machine. After pressure molding, molding was carried out at a pressure of 294 MPa using a cold isostatic press device (CIP device) to obtain a molded body.
The three molded bodies thus obtained were heated to 780°C in an oxygen atmosphere in a sintering furnace, held at 780°C for 5 hours, and further heated to 1325°C. ℃) for 20 hours, and then cooled in a furnace to obtain an oxide sintered body. Note that the temperature increase rate was 2° C./min.
The three obtained oxide sintered bodies were each cut and surface ground to obtain three oxide sintered bodies measuring 142 mm x 305 mm x 5 mm. One of these sheets was used for characteristic evaluation, and two sheets were used for a G1 target [142 mm x 610 mm (divided into 2) x 5 mmt].
For surface grinding, use a surface grinding device to first grind the surface of the oxide sintered body plate using a #100 diamond grinding wheel, and then sequentially grind the oxide sintered body plate using a diamond grinding wheel with a fineness of #200 → #400 → #800. processed.
When the oxide sintered body plate after the grinding process was observed under an optical microscope, no microcracks or the like were particularly observed.

First, the Vickers hardness of one of the three oxide sintered plates obtained was measured, and then the plate was cut to a predetermined size and subjected to various measurements.

(1) Measurement of Vickers hardness Vickers hardness was measured using a Hardness Tester (AKASHI MVK-E3) in accordance with JIS Z 2244:2009. The measurement point was the center line of the oxide sintered body (142 x 305 mm size), and data was collected from 10 points every 30 mm from one end, and the average value was used for evaluation.

(2) Confirmation of crystal structure The oxide sintered body plate whose Vickers hardness had been measured was cut out for X-ray diffraction measurement, and the crystal structure was examined using an X-ray diffraction measurement device (XRD) under the following conditions. As a result, in the oxide sintered body according to Example 1, a hexagonal layered compound represented by In ₂ O ₃ (ZnO) _m (where m = an integer from 2 to 7) and Zn _2-x It was confirmed that a spinel compound represented by Sn _1-y In _x+y O ₄ [0≦x<2, 0≦y<1] existed. FIG. 6 shows an XRD chart of the oxide sintered body according to Example 1.
・Device: Smartlab manufactured by Rigaku Co., Ltd.
・X-ray: Cu-Kα ray (wavelength 1.5418×10 ^-10 m)
・Parallel beam, 2θ-θ reflection method, continuous scan (2.0°/min)
・Sampling interval: 0.02°
・Divergence Slit (DS): 1.0mm
・Scattering Slit (SS): 1.0mm
・Receiving Slit (RS): 1.0mm

(3) Confirmation of composition Similarly, using the remainder of the oxide sintered body plate, the atomic ratio of the oxide sintered body was analyzed using an inductively coupled plasma emission spectrometer (ICP-AES, manufactured by Shimadzu Corporation). The results are as follows.
Zn/(In+Sn+Zn)=0.60
Sn/(Sn+Zn)=0.20
In/(In+Sn+Zn)=0.25

(Examples 2 to 5)
The oxide sintered bodies according to Examples 2 to 5 were produced in the same manner as in Example 1, except that the sintering temperature in Example 1 was changed to the sintering temperature listed in Table 1.

(Comparative Examples 1-2)
The oxide sintered bodies according to Comparative Examples 1 and 2 were produced in the same manner as in Example 1, except that the sintering temperature in Example 1 was changed to the sintering temperature listed in Table 1.
When the oxide sintered body according to Comparative Example 2 was observed with an optical microscope after grinding, microcracks were confirmed.

(Comparative Examples 3-4)
The oxide sintered bodies according to Comparative Examples 3 and 4 were molded using a mold without granulating the raw materials in Example 1, and the sintering temperature was adjusted to the sintering temperature listed in Table 1. It was manufactured in the same manner as in Example 1 except for the changes.

(Comparative Examples 5-6)
The oxide sintered bodies according to Comparative Examples 5 and 6 were produced in the same manner as in Example 1, except that the sintering temperature in Example 1 was changed to the sintering temperature listed in Table 1.

(Manufacture of sputtering target)
Next, by bonding to a backing plate using two oxide sintered plates according to Examples 1 to 5 and Comparative Examples 1 to 6, sputtering of G1 size: 142 mm x 610 mm (divided into 2) x 5 mm Manufactured the target.

The bonding rate was 98% or higher for all targets. When the oxide sintered body was bonded to the backing plate, no cracks occurred in the oxide sintered body, and a sputtering target could be successfully manufactured. The bonding rate (joining rate) was confirmed by X-ray CT.

(Crack resistance during sputtering)
Using the prepared sputtering target, pre-sputtering was performed for 1 hour in a G1 sputtering apparatus under the conditions that the atmospheric gas was 100% Ar and the sputtering power was 1 kW. Here, the G1 sputtering apparatus refers to a first generation sputtering apparatus for mass production with a substrate size of approximately 300 mm x 400 mm. After pre-sputtering, perform continuous discharge for 2 hours while changing the power under the film forming conditions shown in Table 2, open the chamber after discharge, visually check for cracks, increase the power, and repeat the discharge test again. The crack resistance was evaluated.
Crack resistance is the maximum sputtering power that does not cause cracks in the sputtering target. For crack resistance, a case of 1.80 kW or more was considered to be passed. Table 1 shows the evaluation results of the crack resistance of each sputtering target.

It was found that the sputtering targets using the oxide sintered bodies according to Examples 1 to 5 had excellent crack resistance. This is thought to be due to the high Vickers hardness of the surface of the oxide sintered body.
The sputtering targets using the oxide sintered bodies according to Comparative Examples 1, 3, and 4 did not generate microcracks during grinding and polishing, but the crack resistance during sputtering was inferior to Examples 1 to 5. I understand. This is thought to be due to the low Vickers hardness of the surfaces of the oxide sintered bodies of Comparative Examples 1, 3, and 4.
The sputtering target using the oxide sintered body according to Comparative Example 5 did not generate microcracks during grinding and polishing, but it was found that the crack resistance during sputtering was inferior to Examples 1 to 5. This is thought to be due to the low Vickers hardness of the surface of the oxide sintered body according to Comparative Example 5.
Regarding the oxide sintered body according to Comparative Example 6, when the oxide sintered body after the grinding process was observed with an optical microscope, microcracks were confirmed.

1, 1A, 1B, 1C...oxide sintered body, 3...backing plate.

Claims (8)

An oxide sintered body,
The oxide sintered body contains an indium element, a tin element and a zinc element,
The average value of the Vickers hardness of the surface of the oxide sintered body is more than 500 Hv and less than 900 Hv,
Oxide sintered body. A sputtering target comprising the oxide sintered body according to claim 1. 95% by mass or more and 100% by mass or less of the metal elements of the oxide sintered body are indium element, tin element, and zinc element,
The sputtering target according to claim 2. The oxide sintered body further contains X element,
The X element is at least one element selected from the group consisting of germanium element, silicon element, yttrium element, zirconium element, aluminum element, magnesium element, ytterbium element, and gallium element.
The sputtering target according to claim 2 or 3 . The oxide sintered body satisfies the range of atomic composition ratios represented by the following formulas (1), (2) and (3),
The sputtering target according to any one of claims 2 to 4.
0.40≦Zn/(In+Sn+Zn)≦0.80...(1)
0.15≦Sn/(Sn+Zn)≦0.40 (2)
0.10≦In/(In+Sn+Zn)≦0.35 (3) The oxide sintered body is a hexagonal layered compound represented by In ₂ O ₃ (ZnO) m [m=2-7] and Zn _2-x Sn _1-y In _x+y O ₄ [0≦x<2, 0≦y<1], including a spinel structure compound represented by
The sputtering target according to any one of claims 2 to 5. A method for manufacturing a sputtering target for manufacturing the sputtering target according to any one of claims 2 to 6, comprising:
Granulating the raw material for the oxide sintered body to obtain raw material granulated powder having a particle size of 25 μm or more and 150 μm or less;
filling the raw material granulated powder into a mold and molding the raw material granulated powder filled in the mold to obtain a molded body;
Sintering the molded body at a temperature of 1310°C or higher and 1440°C or lower,
A method of manufacturing a sputtering target. The method for manufacturing a sputtering target according to claim 7,
The particle size of the raw material granulated powder is 25 μm or more and 75 μm or less,
A method of manufacturing a sputtering target.

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