KR20210005731A - Oxide sintered body and sputtering target - Google Patents

Abstract

The oxide sintered body according to one aspect of the embodiment is an oxide sintered body containing indium, gallium, and zinc, and includes a homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ , and a spinel structure compound represented by ZnGa ₂ O ₄ And the transverse strength is 180 MPa or more.

Description

Oxide sintered body and sputtering target

Embodiment of the disclosure relates to an oxide sintered body and a sputtering target.

Conventionally, a sputtering target for forming an oxide semiconductor thin film such as IGZO (Indium Gallium Zinc Oxide) has been known. The oxide sintered body used for such a sputtering target contains a homologous structure compound represented by InGaO ₃ (ZnO) _m (m is an integer of 1 to 20) and a spinel structure compound represented by ZnGa ₂ O ₄ (for example See Patent Document 1).

Japanese Patent Publication No. 2008-163441

However, since the conventional oxide sintered body used for a sputtering target has a cross section strength of about 50 MPa, the oxide sintered body is liable to be damaged when a sputtering target is manufactured using such an oxide sintered body or when sputtering is performed with such a sputtering target There was an assignment.

One aspect of the embodiment has been made in view of the above, and an object thereof is to provide an oxide sintered body and a sputtering target capable of suppressing damage.

The oxide sintered body according to one aspect of the embodiment is an oxide sintered body containing indium, gallium, and zinc, and includes a homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ , and a spinel structure compound represented by ZnGa ₂ O ₄ And the transverse strength is 180 MPa or more.

According to one aspect of the embodiment, damage to the oxide sintered body can be suppressed.

1 is an SEM image of an oxide sintered body in Example 1. FIG.

Hereinafter, embodiments of the oxide sintered body disclosed by the present application and a sputtering target will be described with reference to the accompanying drawings. In addition, the present invention is not limited by the embodiments described below.

The oxide sintered body of the embodiment contains indium (In), gallium (Ga), and zinc (Zn). For example, the oxide sintered body of the embodiment contains indium, gallium, zinc, and oxygen (O), and can be used as a sputtering target.

And the oxide sintered body of the embodiment is InGaZnO ₄ (i.e., m = 1) or InGaZn ₂ O ₅ (i.e., m = 2) of the homologous structure compound represented by InGaO ₃ (ZnO) _m (m is an integer). It contains the homologous structure compound shown, and the spinel structure compound shown by ZnGa ₂ O _4, and has a transverse strength of 180 MPa or more.

Thereby, it is possible to suppress damage to the oxide sintered body when producing a sputtering target using such an oxide sintered body or when sputtering with such a sputtering target.

In addition, the oxide sintered body of the embodiment is InGaZnO ₄ (i.e., m = 1) or InGaZn ₂ O ₅ (i.e., m = 2) of the homologous structure compound represented by InGaO ₃ (ZnO) _m (m is an integer). It is preferable that the homologous structure compound shown and the spinel structure compound shown by ZnGa ₂ O ₄ are contained, and the cross-section strength is 180 MPa or more.

In addition, in the homologous structure compound represented by InGaO ₃ (ZnO) _m (m is an integer), if a homologous structure compound represented by m is 3 or more (for example, InGaZn ₃ O ₆ ) is included, a homologous structure compound There is a tendency that the average area of the circle equivalent diameter becomes larger and the break strength decreases. Therefore, among the homologous structural compounds represented by InGaO ₃ (ZnO) _m (m is an integer), it is preferable that the homologous structural compound in which m is 3 or more is not contained.

Moreover, it is more preferable that it is 190 MPa or more, and, as for the oxide sintered compact of embodiment, it is still more preferable that it is 200 MPa or more. The upper limit of the strength of the break is not particularly determined, but is usually 500 MPa or less.

In addition, in the oxide sintered body of the embodiment, it is preferable that the atomic ratio of each element satisfies the following formulas (1) to (3).

0.08<In/(In+Ga+Zn)<0.31 ‥ (1)

0.35<Ga/(In+Ga+Zn)<0.58 ‥ (2)

0.23<Zn/(In+Ga+Zn)<0.46 ‥ (3)

Thereby, the specific resistance of the oxide sintered body can be reduced. Therefore, according to the embodiment, when such an oxide sintered body is used as a sputtering target, sputtering using an inexpensive DC power supply becomes possible, and the film formation rate can be improved.

In addition, in the oxide sintered body of the embodiment, it is preferable that the atomic ratio of each element satisfies the following formulas (4) to (6),

0.08<In/(In+Ga+Zn)≤0.20 ‥ (4)

0.40≤Ga/(In+Ga+Zn)<0.58 ‥ (5)

0.25≤Zn/(In+Ga+Zn)<0.46 ‥ (6)

It is more preferable that the atomic ratio of the atomic ratio of each element satisfies the following formulas (7) to (9),

0.13<In/(In+Ga+Zn)≤0.19 ‥ (7)

0.40≤Ga/(In+Ga+Zn)≤0.55 ‥ (8)

0.27≤Zn/(In+Ga+Zn)<0.46 ‥ (9)

It is more preferable that the atomic ratio of the atomic ratio of each element satisfies the following formulas (10) to (12),

0.14≤In/(In+Ga+Zn)≤0.19 ‥ (10)

0.41≤Ga/(In+Ga+Zn)≤0.53 ‥ (11)

0.30≤Zn/(In+Ga+Zn)≤0.45 ‥ (12)

It is more preferable that the atomic ratio of the atomic ratio of each element satisfies the following formulas (13) to (15).

0.14<In/(In+Ga+Zn)≤0.18 ‥ (13)

0.41≤Ga/(In+Ga+Zn)≤0.52 ‥ (14)

0.31≤Zn/(In+Ga+Zn)≤0.45 ‥ (15)

Thereby, when such an oxide sintered body is used as a sputtering target, the occurrence of arcing can be reduced.

Further, the oxide sintered body of the embodiment may contain inevitable impurities derived from raw materials or the like. Examples of inevitable impurities in the oxide sintered body of the embodiment include Fe, Cr, Ni, Si, W, Cu, Al, and the like, and their content is usually 100 ppm or less.

In addition, in the oxide sintered compact of the embodiment, in cross-sectional observation of the sintered compact, the homologous structural compound preferably has an average area circle equivalent diameter of 10 µm or less, and the homologous structural compound preferably has an average aspect ratio of 2.0 or less. Thereby, since the crystal structure in the oxide sintered body can be refined, the transverse strength of the oxide sintered body can be improved.

Further, in the oxide sintered body of the embodiment, the average area circle equivalent diameter of the homologous structure compound is more preferably 8.0 µm or less, still more preferably 7.0 µm or less, even more preferably 6.0 µm or less, and more than 5.0 µm or less. It is even more preferable. The lower limit of the average circle equivalent diameter of the homologous structure compound is not particularly determined, but is usually 2.0 µm or more.

Further, in the oxide sintered body of the embodiment, the average aspect ratio of the homologous structure compound is more preferably 1.9 or less, still more preferably 1.8 or less, and even more preferably 1.75 or less. The lower limit of the average aspect ratio of the homologous structure compound is not particularly determined, but is usually 1.0 or more.

Further, in the oxide sintered compact of the embodiment, in cross-sectional observation of the sintered compact, the spinel structure compound preferably has an average area-circle equivalent diameter of 5.0 µm or less, and the spinel structure compound preferably has an average aspect ratio of 2.0 or less. Thereby, since the crystal structure in the oxide sintered body can be refined, the transverse strength of the oxide sintered body can be improved.

Further, in the oxide sintered body of the embodiment, the spinel structure compound has an equivalent average area circle diameter of 4.5 µm or less, still more preferably 4.0 µm or less, and even more preferably 3.8 µm or less. The lower limit of the average circle equivalent diameter of the spinel structure compound is not particularly determined, but is usually 2.0 µm or more.

In addition, in the oxide sintered body of the embodiment, the average aspect ratio of the spinel structure compound is more preferably 1.8 or less, still more preferably 1.7 or less, and even more preferably 1.6 or less. The lower limit of the average aspect ratio of the spinel structure compound is not particularly determined, but is usually 1.0 or more.

In addition, in the oxide sintered body of the embodiment, in cross-sectional observation of the sintered body, it is preferable that the area ratio of the spinel structure compound is 15% or more. Thereby, the relative density of the oxide sintered body can be increased, and the transverse strength can be improved.

Further, in the oxide sintered body of the embodiment, it is more preferable that the area ratio of the spinel structure compound is 25% or more, still more preferably 35% or more, still more preferably 40% or more, and even more preferably 45% or more.

In addition, it is preferable that the area ratio of the spinel structure compound is 80% or less in the oxide sintered body of the embodiment. Thereby, the specific resistance of the oxide sintered body can be reduced.

Further, in the oxide sintered body of the embodiment, the area ratio of the spinel structure compound is more preferably 70% or less, still more preferably 65% or less, even more preferably 60% or less, and even more preferably 55% or less.

Further, it is preferable that the oxide sintered body of the embodiment has a relative density of 99.5% or more. Thereby, when such an oxide sintered body is used as a sputtering target, the discharge state of DC sputtering can be stabilized.

When the relative density is 99.5% or more, when such an oxide sintered body is used as a sputtering target, it is possible to reduce voids in the sputtering target, and it is easy to prevent introduction of gas components into the atmosphere. In addition, during sputtering, it becomes difficult to generate abnormal discharges, cracks in the sputtering target, or the like with such voids as a starting point.

Further, in the oxide sintered body of the embodiment, it is more preferable that the relative density is 99.8% or more, still more preferably 100.0% or more, still more preferably 100.5% or more, and even more preferably 101.0% or more. The upper limit of the relative density is not particularly determined, but is usually 105%.

Further, it is preferable that the oxide sintered body of the embodiment has a specific resistance of 5.0 × 10 ^-1 Ω·cm or less. Thereby, when such an oxide sintered body is used as a sputtering target, sputtering using an inexpensive DC power supply becomes possible, and the film formation rate can be improved.

Further, the oxide sintered body of the embodiment has a specific resistance of 5.0 × 10 ^-2 Ω·cm or less, more preferably, a specific resistance of 4.0 × 10 ^-2 Ω·cm or less, and 3.5 × 10 ^-2 Ω·cm or less. It is even more preferable. The lower limit of the specific resistance is not particularly determined, but is usually 1.0×10 ^-4 Ω·cm or more. In addition, the specific resistance of the oxide sintered body of the embodiment can be measured according to JIS K 7194.

<Each manufacturing process of the oxide sputtering target>

The oxide sputtering target of the embodiment can be produced, for example, by a method as shown below. First, the raw material powder is mixed. The raw material powder is usually In ₂ O ₃ powder, Ga ₂ O ₃ powder and ZnO powder.

The mixing ratio of each raw material powder is appropriately determined so as to be a desired ratio of constituent elements in the oxide sintered body.

Each raw material powder may be dry mixed in advance. The method of dry mixing is not particularly limited, and for example, ball mill mixing in which each raw material powder and zirconia balls are placed in a pot and mixed may be used. As a method of manufacturing a molded article from the mixed powder thus mixed, for example, a slip casting method or a CIP (Cold Isostatic Pressing method) may be mentioned. Subsequently, as specific examples of the molding method, two types of methods will be described, respectively.

(Slip cast method)

In the slip casting method described herein, a slurry containing a mixed powder and an organic additive is prepared using a dispersion medium, and the slurry is poured into a mold and the dispersion medium is removed to perform molding. Organic additives that can be used here are known binders and dispersants.

In addition, the dispersion medium used when preparing the slurry is not particularly limited, and may be appropriately selected from water or alcohol depending on the purpose. Also, the method of preparing the slurry is not particularly limited, and for example, ball mill mixing in which a mixed powder, an organic additive, and a dispersion medium are put into a pot and mixed may be used. The slurry thus obtained is poured into a mold and the dispersion medium is removed to prepare a molded article. The mold which can be used here is a metal type, a gypsum type, a resin type which removes a dispersion medium by pressure, and the like.

(CIP method)

In the CIP method described herein, a slurry containing a mixed powder and an organic additive is prepared using a dispersion medium, and the dry powder obtained by spray drying such a slurry is charged into a mold, and pressure molding is performed. Organic additives that can be used here are known binders and dispersants.

In addition, the dispersion medium used when preparing the slurry is not particularly limited, and may be appropriately selected from water or alcohol depending on the purpose. Also, the method of preparing the slurry is not particularly limited, and for example, ball mill mixing in which a mixed powder, an organic additive, and a dispersion medium are put into a pot and mixed may be used.

The thus-obtained slurry is spray-dried to produce a dry powder having a water content of 1% or less, and the dry powder is charged into a mold and pressurized by the CIP method to produce a molded article.

Next, the obtained molded body is fired to produce a sintered body. There is no particular limitation on the sintering furnace for producing such a sintered body, and a sintering furnace that can be used for producing the ceramic sintered body can be used. Such firing may be performed in an atmosphere in which oxygen is present.

In the present invention, the firing temperature is required to be 1450°C or higher, and is preferably 1480°C or higher. By setting the firing temperature to 1450°C or higher, the sintered compact of the present invention with high density and high strength can be obtained. On the other hand, from the viewpoint of suppressing the enlargement of the structure of the sintered body and preventing cracking, the firing temperature is preferably 1600°C or less, and more preferably 1550°C or less.

Next, the obtained sintered body is cut. Such cutting is performed using a surface grinding machine or the like. Further, the surface roughness Ra after cutting can be appropriately controlled by selecting the size of the abrasive grains of the grindstone used for cutting.

A sputtering target is produced by bonding the cut sintered body to the substrate. As the material of the substrate, stainless steel, copper, titanium, or the like can be appropriately selected. As the bonding material, a low melting point solder such as indium can be used.

Example

[Example 1]

In ₂ O ₃ powder with an average particle diameter of 0.6 μm, Ga ₂ O ₃ powder with an average particle diameter of 1.5 μm, and ZnO powder with an average particle diameter of 0.8 μm are dry-mixed by a ball mill using zirconia balls in a pot to prepare a mixed powder. I did.

In addition, the average particle diameter of the raw material powder was measured using a particle size distribution measuring apparatus HRA manufactured by Nikkiso Corporation. In this measurement, water was used as a solvent, and it was measured at a refractive index of 2.20 of the measurement material. Moreover, it was set as the same measurement conditions also about the average particle diameter of the raw material powder described below. In addition, the average particle diameter of the raw material powder is a volume cumulative particle diameter D ₅₀ in a cumulative volume of 50% by volume by a laser diffraction scattering particle size distribution measurement method.

In addition, when preparing such a mixed powder, each raw material powder was blended so that the atomic ratio of metal elements contained in all raw material powders was In: Ga: Zn = 0.17: 0.50: 0.33.

Next, to the pot where the mixed powder was prepared, 0.2% by mass of a binder with respect to the mixed powder, 0.6% by mass of a dispersant with respect to the mixed powder, and 20% by mass of water with respect to the mixed powder as a dispersion medium were added, and ball mill mixing Thus, a slurry was prepared.

Next, the prepared slurry was poured into a metal mold fitted with a filter, and drained to obtain a molded article. Next, this molded body was fired to produce a sintered body. Such firing was performed at a firing temperature of 1500°C, a firing time of 8 hours, a temperature increase rate of 50°C/h, and a temperature decrease rate of 50°C/h in an atmosphere with an oxygen concentration of 20%.

Next, the obtained sintered body was cut to obtain an oxide sintered body having a surface roughness Ra of 1.0 µm and a width of 210 mm x a length of 710 mm x a thickness of 6 mm. In addition, a grindstone of #170 was used for this cutting process.

[Examples 2 and 3]

An oxide sintered body was obtained using the same method as in Example 1. In Examples 2 and 3, when preparing the mixed powder, each raw material powder was blended so that the atomic ratio of metal elements contained in all raw material powders became the atomic ratios shown in Table 1.

[Comparative Examples 1 to 4]

An oxide sintered body was obtained using the same method as in Example 1. In Comparative Examples 1 to 4, when preparing the mixed powder, each raw material powder was blended so that the atomic ratio of metal elements contained in all raw material powders became the atomic ratios shown in Table 1.

In addition, in Examples 1 to 3 and Comparative Examples 1 to 4, the ratio of each element measured when producing each raw material powder is equal to the ratio of each element in the obtained oxide sintered body, ICP-AES (Inductively Coupled) Plasma Atomic Emission Spectroscopy: Inductively coupled plasma emission spectroscopy).

Subsequently, the relative density of the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 4 obtained above was measured. This relative density was determined based on the Archimedes method.

Specifically, the air mass of the oxide sintered body is divided by the volume (the mass in water of the sintered body / the water specific gravity at the measurement temperature), and the value of the percentage to the theoretical density ρ (g/cm 3) is expressed as the relative density (unit: %). I did.

In addition, this theoretical density ρ (g/cm 3) was calculated from the mass% and density of the raw material powder used in the production of the oxide sintered body. Specifically, it was calculated by the following formula (7).

ρ={(C ₁ /100)/ρ ₁ +(C ₂ /100)/ρ ₂ +(C ₃ /100)/ρ ₃ } ^-1 ‥ (7)

In addition, in the above formula, C ₁ to C ₃ and ρ ₁ to ρ ₃ each represent the following values.

C ₁ : Mass% of In ₂ O ₃ powder used in the manufacture of the oxide sintered body

·Ρ ₁ : Density of In ₂ O ₃ (7.18g/cm3)

C ₂ : Mass% of Ga ₂ O ₃ powder used in the manufacture of the oxide sintered body

·Ρ ₂ : Density of Ga ₂ O ₃ (5.95 g/cm 3)

C ₃ : Mass% of the ZnO powder used in the manufacture of the oxide sintered body

·Ρ ₃ : Density of ZnO (5.60g/cm3)

Subsequently, the specific resistance (bulk resistance) was measured for each of the oxide sintered bodies for sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 4 obtained above.

Specifically, using the Mitsubishi Chemical Co., Ltd. Loresta (registered trademark) HP MCP-T410 (serial 4 probe probe TYPE ESP), the probe was brought into contact with the surface of the processed oxide sintered body and measured in AUTO RANGE mode. I did. The measurement points were taken as a total of 5 locations in the vicinity of the center of the oxide sintered body and 4 corners, and the average value of each measurement was taken as the bulk resistance value of the sintered body.

Subsequently, each of the oxide sintered compacts for sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 4 obtained above was measured for the break strength. Such transverse strength was obtained from JIS-R-1601 (bending strength test method of fine ceramics) using a sample piece (length 36 mm or more, width 4.0 mm, thickness 3.0 mm) cut from an oxide sintered body by wire electric discharge machining. It was measured according to the measuring method of point bending strength.

Subsequently, the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 4 obtained above were each subjected to X-Ray Diffraction (XRD) measurement to obtain an X-ray diffraction chart. And the constitutional phase contained in the oxide sintered body was identified by the obtained X-ray diffraction chart.

In addition, specific measurement conditions for such X-ray diffraction measurement were as follows.

Equipment: SmartLab (manufactured by Rigaku Corporation, registered trademark)

· Source: CuKα line

·Tube voltage: 40kV

·Tube current: 30mA

Scan speed: 5deg/min

Step: 0.02deg

Scan range: 2θ = 20 degrees to 80 degrees

Subsequently, while observing the surfaces of the oxide sintered bodies for sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 4 obtained above using a scanning electron microscope (SEM), the composition of the crystal The crystal shape was evaluated.

Specifically, the cut surface obtained by cutting the oxide sintered body was polished step by step using emery paper #180, #400, #800, #1000, and #2000, and finally buffed to finish a mirror surface.

Thereafter, an etching solution of 40°C (nitric acid (60 to 61% aqueous solution, manufactured by Kanto Chemical Co., Ltd.), hydrochloric acid (35.0 to 37.0% aqueous solution, manufactured by Kanto Chemical Co., Ltd.) and pure water are used in a volume ratio of HCl:H ₂ O: HNO ₃ = 1: 1: 0.08 (mixed in the ratio) was immersed for 2 minutes to perform etching.

Then, the exposed surface was observed using a scanning electron microscope (SU3500, manufactured by Hitachi High-Technologies Co., Ltd.). Further, in the evaluation of the crystal shape, a BSE-COMP image having a magnification of 500 times and a range of 175 µm × 250 µm was randomly photographed with 10 fields of view to obtain a SEM image of the structure as shown in FIG. 1.

1 is an SEM image of an oxide sintered body in Example 1. FIG. In addition, in FIG. 1, a crystal with a light color is a homologous structure compound, and a crystal with a dark color is a spinel structure compound.

In addition, for particle analysis, image processing software ImageJ 1.51k (http://imageJ.nih.gov/ij/) provided by National Institutes of Health (NIH) was used.

First, the BSE-COMP image obtained above was drawn according to the grain boundaries of the homologous structure compound, and after all the drawing was completed, image correction (Image → Adjust → Threshold) was performed to remove the spinel structure compound. Noise remaining after image correction was removed (Process → Noise → Despeckle) as necessary.

After that, particle analysis was performed (Analyze → Analyze Particles) to obtain the area and aspect ratio of each particle. After that, the area circle equivalent diameter was calculated from the area in each obtained particle. These average values of all the particles calculated at 10 fields of view were taken as the average area circle equivalent diameter and average aspect ratio of the homologous structural compound in the present invention (referred to as IGZO phase in Table 1).

Next, the BSE-COMP image obtained above was drawn according to the grain boundaries of the spinel structure compound, and after all the drawing was completed, image correction (Image → Adjust → Threshold) was performed to remove the homologous structure compound. Noise remaining after image correction was removed (Process → Noise → Despeckle) as necessary.

After that, particle analysis was performed (Analyze → Analyze Particles) to obtain the area and aspect ratio of each particle. After that, the area circle equivalent diameter was calculated from the area in each obtained particle. These average values of all the particles calculated at 10 fields of view were taken as the average area circle equivalent diameter and average aspect ratio of the spinel structure compound in the present invention (referred to as GZO phase in Table 1).

Here, for the above-described Examples 1 to 3 and Comparative Examples 1 to 4, the atomic ratio of each element contained in the mixed powder, the relative density of the oxide sintered body, specific resistance (bulk resistance), the transverse strength, configuration, homomol Table 1 shows the measurement results of the average area circle equivalent diameter and average aspect ratio of the Logus structure compound (IGZO phase) and the spinel structure compound (GZO phase), and the area ratio of the spinel structure compound (GZO phase).

It can be seen that all of the oxide sintered bodies of Examples 1 to 3 have a relative density of 99.5% or more. Therefore, according to the embodiment, when such an oxide sintered body is used as a sputtering target, the discharge state of DC sputtering can be stabilized.

In addition, it can be seen that all of the oxide sintered bodies of Examples 1 to 3 have a specific resistance of 5.0×10 ^-1 Ωcm or less. Therefore, according to the embodiment, when the oxide sintered body is used as a sputtering target, sputtering using an inexpensive DC power supply becomes possible and the film formation rate can be improved.

In addition, it can be seen that all of the sintered oxide bodies of Examples 1 to 3 have a rupture strength of 180 MPa or more. Therefore, according to the embodiment, when a sputtering target is produced using such an oxide sintered body, or when sputtering is performed on such a sputtering target, it is possible to suppress damage to the oxide sintered body.

Further, it can be seen that the oxide sintered bodies of Examples 1 to 3 contain a homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ and a spinel structure compound represented by ZnGa ₂ O ₄ . Therefore, according to the embodiment, an IGZO oxide sintered body having high transverse strength can be realized.

In addition, by comparison between Examples 1 to 3 and Comparative Examples 2 and 3, homologous compounds in which m is 3 or more are included among homologous compounds represented by InGaO ₃ (ZnO) _m (m is an integer). As a result, it can be seen that the transverse strength is lowered.

In addition, Examples 1 to 3 containing In, Ga, and Zn in the ranges shown in Formulas (1) to (3), including homologous structural compounds represented by InGaZnO ₄ or InGaZn ₂ O ₅ , and such From the comparison of Comparative Example 4 which does not contain In, Ga, or Zn in the range, it can be seen that the specific resistance is reduced to 5.0 × 10 ^-1 Ωcm or less by containing In, Ga and Zn in this range.

In addition, by comparing Examples 1 to 3 in which the area ratio of the spinel structure compound is 80% or less and Comparative Example 4 in which the area rate of the spinel structure compound is greater than 80%, the area ratio of the spinel structure compound is set to 80% or less. It can be seen that this is reduced.

In addition, it can be seen that the oxide sintered bodies of Examples 1 to 3 all have an average area circle equivalent diameter of the homologous structure compound of 10 µm or less, and that the homologous structure compound has an average aspect ratio of 2.0 or less. Thereby, since the crystal structure in the oxide sintered body can be refined, the transverse strength of the oxide sintered body can be improved.

In addition, it can be seen that the oxide sintered bodies of Examples 1 to 3 all have an average area circle equivalent diameter of the spinel structure compound of 5 µm or less, and the average aspect ratio of the spinel structure compound is 2.0 or less. Thereby, since the crystal structure in the oxide sintered body can be refined, the transverse strength of the oxide sintered body can be improved.

In addition, it can be seen that the sintered oxide bodies of Examples 1 to 3 all have an area ratio of 15% or more of the spinel structure compound. In this way, the sintered strength of the oxide sintered body can be improved.

Next, 10 sheets of each of the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 4 described above were joined using In solder as the base material. As a result, no cracks were observed in the oxide sintered bodies of Examples 1 to 3 and Comparative Example 1. On the other hand, three, four, and two cracks were observed in the oxide sintered bodies of Comparative Examples 2 to 4, respectively.

Next, sputtering was performed using the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 2 and 3 described above, and the target was evaluated from the amount of arcing. In addition, the oxide sintered bodies of Comparative Examples 1 and 4 had high specific resistance, so that DC sputtering was not possible.

(Sputtering condition)

Device: DC magnetron sputtering device, exhaust system cryopump, rotary pump

Reached vacuum degree: 3×10 ^-6 Pa

Sputter pressure: 0.4Pa

Oxygen partial pressure: 1×10 ^-3 Pa

Input power amount time: 2W/㎠

Time: 10 hours

(Arking counter)

Format: μArc Moniter MAM Genesis MAM Data Collector Ver.2.02

(Manufactured by LANDMARK TECHNOLOGY)

(Arking evaluation)

A: 20 or less

B: 21 to 50 times

C: 51 to 100 times

D: 101 times or more

Further, cracking of the oxide sintered body was also confirmed after sputtering. Table 2 shows the evaluation results.

Comparison of Examples 1 and 2 in which the atomic ratio of each element satisfies Equations (7) to (9) and Comparative Examples 2 and 3 in which the atomic ratio of the atomic ratio of each element does not satisfy Equations (7) to (9) As a result, it can be seen that the occurrence of arcing and cracking of the oxide sintered body is reduced by satisfying the formulas (7) to (9) in the atomic ratio of each element.

In addition, by comparison between Example 1 in which the atomic ratio of each element satisfies the equations (13) to (15) and Example 2 in which the atomic ratio of each element does not satisfy the equations (13) to (15), It can be seen that the occurrence of arcing is further reduced by the atomic ratio satisfying the equations (13) to (15).

As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit thereof. For example, in the embodiment, an example in which a sputtering target was produced using a plate-shaped oxide sintered body was shown, but the shape of the oxide sintered body is not limited to a plate shape, and any shape such as a cylinder may be used.

Additional effects or modifications can be easily derived by those skilled in the art. For this reason, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes may be made without departing from the spirit or scope of the concept of the general invention defined by the appended claims and their equivalents.

Claims (16)

As an oxide sintered body containing indium, gallium and zinc,
A homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ and a spinel structure compound represented by ZnGa ₂ O ₄ ,
An oxide sintered body having a rupture strength of 180 MPa or more. The method of claim 1,
An oxide sintered body in which the atomic ratio of each element satisfies the following formula.
0.08<In/(In+Ga+Zn)<0.31
0.35<Ga/(In+Ga+Zn)<0.58
0.23<Zn/(In+Ga+Zn)<0.46 The method according to claim 1 or 2,
An oxide sintered body in which the atomic ratio of each element satisfies the following formula.
0.08<In/(In+Ga+Zn)≤0.20
0.40≤Ga/(In+Ga+Zn)<0.58
0.25≤Zn/(In+Ga+Zn)<0.46 The method according to any one of claims 1 to 3,
An oxide sintered body in which the atomic ratio of each element satisfies the following formula.
0.13<In/(In+Ga+Zn)≤0.19
0.40≤Ga/(In+Ga+Zn)≤0.55
0.27≤Zn/(In+Ga+Zn)<0.46 The method according to any one of claims 1 to 4,
An oxide sintered body in which the atomic ratio of each element satisfies the following formula.
0.14≤In/(In+Ga+Zn)≤0.19
0.41≤Ga/(In+Ga+Zn)≤0.53
0.30≤Zn/(In+Ga+Zn)≤0.45 The method according to any one of claims 1 to 5,
An oxide sintered body in which the atomic ratio of each element satisfies the following formula.
0.14<In/(In+Ga+Zn)≤0.18
0.41≤Ga/(In+Ga+Zn)≤0.52
0.31≤Zn/(In+Ga+Zn)≤0.45 The method according to any one of claims 1 to 6,
The homologous structure compound has an average area circle equivalent diameter of 10 μm or less,
Oxide sintered body. The method according to any one of claims 1 to 7,
The homologous structure compound has an average aspect ratio of 2.0 or less,
Oxide sintered body. The method according to any one of claims 1 to 8,
The spinel structure compound has an average area circle equivalent diameter of 5 μm or less,
Oxide sintered body. The method according to any one of claims 1 to 9,
The spinel structure compound has an average aspect ratio of 2.0 or less,
Oxide sintered body. The method according to any one of claims 1 to 10,
The spinel structure compound has an area ratio of 15% or more,
Oxide sintered body. The method according to any one of claims 1 to 11,
The spinel structure compound has an area ratio of 80% or less,
Oxide sintered body. The method according to any one of claims 1 to 12,
Having a relative density of 99.5% or more,
Oxide sintered body. The method according to any one of claims 1 to 13,
Resistivity is 5.0×10 ^-1 Ωcm or less,
Oxide sintered body. The method according to any one of claims 1 to 14,
A homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ , and a spinel structure compound represented by ZnGa ₂ O ₄ ,
Oxide sintered body. Using the oxide sintered body according to any one of claims 1 to 15 as a target material,
Sputtering target.

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