JP7282766B2 - Oxide sintered body and sputtering target - Google Patents

Description

Embodiments of the disclosure relate to sintered oxides and sputtering targets.

Conventionally, a sputtering target for forming an oxide semiconductor thin film such as IGZO (Indium Gallium Zinc Oxide) is known. The oxide sintered body used for such a sputtering target includes 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 . (See Patent Document 1, for example).

JP 2008-163441 A

However, since the oxide sintered body used for a conventional sputtering target has a bending strength of about 50 MPa, when manufacturing a sputtering target using such an oxide sintered body or performing sputtering with such a sputtering target When carrying out, the subject that the oxide sintered compact was easy to be damaged occurred.

One aspect of the embodiments 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 breakage.

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

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

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

EMBODIMENT OF THE INVENTION Hereafter, with reference to an accompanying drawing, embodiment of the oxide sintered compact and sputtering target which this application discloses is described. In addition, this invention is not limited by embodiment shown 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 is made of indium, gallium, zinc, and oxygen (O), and can be used as a sputtering target.

Then, the oxide sintered body _{of the embodiment includes InGaZnO 4 (} that is, _m =1) or InGaZn ₂ O ₅ (that is, It contains a homologous structure compound represented by m=2) and a spinel structure compound represented by ZnGa ₂ O ₄ and has a bending strength of 180 MPa or more.

Thereby, when manufacturing a sputtering target using such an oxide sintered body, or when performing sputtering with such a sputtering target, it is possible to suppress the oxide sintered body from being damaged.

Further, the oxide sintered body of the embodiment includes InGaZnO _{4 (} that is, _m =1) or InGaZn ₂ O ₅ (that is, It preferably comprises a homologous structure compound represented by m=2) and a spinel structure compound represented by ZnGa ₂ O ₄ and has a bending strength of 180 MPa or more.

Among the homologous structure compounds represented by InGaO ₃ (ZnO) _m (m is an integer), homologous structure compounds represented by m being 3 or more (for example, InGaZn ₃ O ₆ ) are included. There is a tendency for the average area equivalent circle diameter to increase and the bending strength to decrease. Therefore, among homologous structure compounds represented by InGaO ₃ (ZnO) _m (m is an integer), it is preferable not to include homologous structure compounds represented by m being 3 or more.

The oxide sintered body of the embodiment preferably has a bending strength of 190 MPa or more, more preferably 200 MPa or more. Although the upper limit of the bending strength is not particularly defined, it is usually 500 MPa or less.

In the oxide sintered body of the embodiment, the atomic ratio of each element preferably 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 the oxide sintered body of the embodiment, the atomic ratio of each element preferably 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)
More preferably, 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)
More preferably, 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)
More preferably, the atomic ratio of the atomic ratios of the respective elements 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.

In addition, the oxide sintered body of the embodiment may contain unavoidable impurities derived from raw materials and the like. Inevitable impurities in the oxide sintered body of the embodiment include Fe, Cr, Ni, Si, W, Cu, Al and the like, and their contents are usually 100 ppm or less.

In addition, in the cross-sectional observation of the sintered body, the oxide sintered body of the embodiment preferably has an average area equivalent circle diameter of the homologous structure compound of 10 μm or less, and an average aspect ratio of the homologous structure compound of 2.0 or less. is preferred. As a result, the crystal structure in the oxide sintered body can be refined, so that the bending strength of the oxide sintered body can be improved.

In the oxide sintered body of the embodiment, the average equivalent circle diameter of the homologous structure compound is more preferably 8.0 μm or less, more preferably 7.0 μm or less, and 6.0 μm or less. is even more preferable, and 5.0 μm or less is even more preferable. Although the lower limit of the average area-equivalent circle diameter of the homologous structure compound is not particularly defined, it is usually 2.0 μm or more.

In the oxide sintered body of the embodiment, the average aspect ratio of the homologous structure compound is more preferably 1.9 or less, more preferably 1.8 or less, and 1.75 or less. More preferred. Although the lower limit of the average aspect ratio of the homologous structure compound is not particularly defined, it is usually 1.0 or more.

Further, in the oxide sintered body of the embodiment, the average area equivalent circle diameter of the spinel structure compound is preferably 5.0 μm or less, and the average aspect ratio of the spinel structure compound is 2.0 μm or less when the cross section of the sintered body is observed. It is preferably 0 or less. As a result, the crystal structure in the oxide sintered body can be refined, so that the bending strength of the oxide sintered body can be improved.

In the oxide sintered body of the embodiment, the average area equivalent circle diameter of the spinel structure compound is more preferably 4.5 μm or less, more preferably 4.0 μm or less, and 3.8 μm or less. is more preferable. Although the lower limit of the average area-equivalent circle diameter of the spinel structure compound is not particularly defined, it is usually 2.0 μm or more.

In the oxide sintered body of the embodiment, the average aspect ratio of the spinel structure compound is more preferably 1.8 or less, more preferably 1.7 or less, and 1.6 or less. More preferred. Although the lower limit of the average aspect ratio of the spinel structure compound is not particularly defined, it is usually 1.0 or more.

Further, in the oxide sintered body of the embodiment, the area ratio of the spinel structure compound is preferably 15% or more in cross-sectional observation of the sintered body. Thereby, the relative density of the oxide sintered body can be increased, and the bending strength can be improved.

In the oxide sintered body of the embodiment, the area ratio of the spinel structure compound is more preferably 25% or more, more preferably 35% or more, even more preferably 40% or more. % or more is even more preferable.

Moreover, in the oxide sintered body of the embodiment, the area ratio of the spinel structure compound is preferably 80% or less. Thereby, the specific resistance of the oxide sintered body can be reduced.

In the oxide sintered body of the embodiment, the area ratio of the spinel structure compound is more preferably 70% or less, further preferably 65% or less, and even more preferably 60% or less. % or less is even more preferable.

Moreover, the oxide sintered body of the embodiment preferably 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, voids can be reduced in the sputtering target, and it is easy to prevent intake of atmospheric gas components. In addition, during sputtering, abnormal discharge originating from such gaps, cracking of the sputtering target, and the like are less likely to occur.

The oxide sintered body of the embodiment preferably has a relative density of 99.8% or more, more preferably 100.0% or more, and even more preferably 100.5% or more. , 101.0% or more. Although the upper limit of the relative density is not particularly defined, it is usually 105%.

Further, the oxide sintered body of the embodiment preferably 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.

The oxide sintered body of the embodiment more preferably has a specific resistance of 5.0×10 ⁻² Ω·cm or less, and a specific resistance of 4.0×10 ⁻² Ω·cm or less. is more preferable, and 3.5×10 ⁻² Ω·cm or less is even more preferable. Although the lower limit of the resistivity is not particularly defined, it is usually 1.0×10 ⁻⁴ Ω·cm or more. In addition, the specific resistance of the oxide sintered body of embodiment can be measured according to JISK7194.

<Each manufacturing process of the oxide sputtering target>
The oxide sputtering target of the embodiment can be manufactured, for example, by the method shown below. First, raw material powders are mixed. Raw material powders are generally 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 achieve a desired ratio of constituent elements in the oxide sintered body.

Each raw material powder may be dry mixed in advance. The dry mixing method 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 can be used. Examples of methods for producing a compact from the mixed powder thus mixed include a slip casting method and CIP (Cold Isostatic Pressing). Next, two types of methods will be described as specific examples of the molding method.

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

Moreover, the dispersion medium used in preparing the slurry is not particularly limited, and can be appropriately selected from water, alcohol, and the like, depending on the purpose. Also, the method for preparing the slurry is not particularly limited, and for example, ball mill mixing in which the mixed powder, the organic additive, and the dispersion medium are placed in a pot and mixed can be used. The slurry thus obtained is poured into a mold, and the dispersion medium is removed to produce a compact. The molds that can be used here include metal molds, gypsum molds, resin molds that remove dispersion medium under pressure, and the like.

(CIP method)
In the CIP method described here, a slurry containing a mixed powder and an organic additive is prepared using a dispersion medium, and the dry powder obtained by spray-drying the slurry is filled in a mold and pressure-molded. I do. Organic additives that can be used here include known binders and dispersants.

Moreover, the dispersion medium used in preparing the slurry is not particularly limited, and can be appropriately selected from water, alcohol, and the like, depending on the purpose. Also, the method for preparing the slurry is not particularly limited, and for example, ball mill mixing in which the mixed powder, the organic additive and the dispersion medium are placed in a pot and mixed can be used.

The slurry thus obtained is spray-dried to prepare a dry powder having a moisture content of 1% or less, and the dry powder is filled in a mold and pressure-molded by a CIP method to prepare a compact. .

Next, the obtained molded body is fired to produce a sintered body. A firing furnace for producing such a sintered body is not particularly limited, and a firing furnace that can be used for producing a ceramic sintered body can be used. Such firing is preferably performed in an atmosphere in which oxygen is present.

In the present invention, the firing temperature must be 1450° C. or higher, preferably 1480° C. or higher. By setting the sintering temperature to 1450° C. or higher, it is possible to obtain the high-density and high-strength sintered body of the present invention. On the other hand, from the viewpoint of suppressing enlargement of the structure of the sintered body and preventing cracks, the firing temperature is preferably 1600° C. or lower, more preferably 1550° C. or lower.

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

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

[Example 1]
In ₂ O ₃ powder with an average particle size of 0.6 μm, Ga ₂ O ₃ powder with an average particle size of 1.5 μm, and ZnO powder with an average particle size of 0.8 μm were mixed into zirconia balls in a pot. A mixed powder was prepared by ball mill dry mixing.

The average particle size of the raw material powder was measured using a particle size distribution analyzer HRA manufactured by Nikkiso Co., Ltd. In this measurement, water was used as a solvent, and the refractive index of the substance to be measured was 2.20. The same measurement conditions were used for the average particle size of the raw material powder described below. The average particle size of the raw material powder is the volume cumulative particle size _D50 at a cumulative volume of 50% by volume measured by a laser diffraction/scattering particle size distribution measurement method.

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

Next, in the pot in which 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% with respect to the mixed powder as a dispersion medium % by mass of water was added and mixed in a ball mill to prepare a slurry.

Next, the prepared slurry was poured into a metal mold sandwiching a filter and drained to obtain a compact. Next, this molded body was fired to produce a sintered body. The firing was carried out in an atmosphere with an oxygen concentration of 20% 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.

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

[Examples 2 and 3]
Using the same method as in Example 1, an oxide sintered body was obtained. In Examples 2 and 3, the raw material powders were blended so that the atomic ratios of the metal elements contained in all the raw material powders were the atomic ratios shown in Table 1 when the mixed powders were prepared.

[Comparative Examples 1 to 4]
Using the same method as in Example 1, an oxide sintered body was obtained. In Comparative Examples 1 to 4, the raw material powders were blended so that the atomic ratios of the metal elements contained in all the raw material powders were the atomic ratios shown in Table 1 when the mixed powders were prepared.

In Examples 1 to 3 and Comparative Examples 1 to 4, it was confirmed that the ratio of each element weighed when preparing each raw material powder was equal to the ratio of each element in the obtained oxide sintered body. It was measured by AES (Inductively Coupled Plasma Atomic Emission Spectroscopy).

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

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

Also, the theoretical density ρ (g/cm ³ ) was calculated from the mass % and density of the raw material powder used for producing 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)

Note that C ₁ to C ₃ and ρ ₁ to ρ ₃ in the above formula respectively indicate the following values.
・C ₁ : % by mass of the In ₂ O ₃ powder used in the production of the oxide sintered body
・ρ ₁ : Density of In ₂ O ₃ (7.18 g/cm ³ )
・C ₂ : % by mass of the Ga ₂ O ₃ powder used in the production of the oxide sintered body
・ρ ₂ : Density of Ga ₂ O ₃ (5.95 g/cm ³ )
・C ₃ : % by mass of the ZnO powder used in the production of the oxide sintered body
・ρ ₃ : Density of ZnO (5.60 g/cm ³ )

Subsequently, 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 Loresta (registered trademark) HP MCP-T410 (series 4-probe probe TYPE ESP) manufactured by Mitsubishi Chemical Corporation, a probe is applied to the surface of the oxide sintered body after processing, and AUTO RANGE mode was measured. Measurement points were five points in total, near the center and four corners of the oxide sintered body, and the average value of the measured values was taken as the bulk resistance value of the sintered body.

Subsequently, bending strength 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. Such bending strength is measured using a sample piece (length 36 mm or more, width 4.0 mm, thickness 3.0 mm) cut out from an oxide sintered body by wire electric discharge machining, and JIS-R-1601 (bending strength of fine ceramics Measured according to the method for measuring three-point bending strength in Test Method).

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 (X-Ray Diffraction: XRD) measurement to obtain an X-ray diffraction chart. rice field. Then, the constituent phases contained in the oxide sintered body were identified from the obtained X-ray diffraction chart.

In addition, the specific measurement conditions of this X-ray diffraction measurement were as follows.
・ Apparatus: SmartLab (manufactured by Rigaku Co., Ltd., registered trademark)
・Radiation source: CuKα ray ・Tube voltage: 40 kV
・Tube current: 30mA
・Scanning speed: 5deg/min
・Step: 0.02deg
・Scan range: 2θ = 20 degrees to 80 degrees

Subsequently, the surfaces of the oxide sintered bodies for sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 4 obtained above were observed using a scanning electron microscope (SEM). , the constituent phases of the crystal and the crystal shape were evaluated.

Specifically, the cut surface obtained by cutting the oxide sintered body is polished in stages using #180, #400, #800, #1000, and #2000 emery papers, and finally buffed. and mirror-finished.

After that, etching solution (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 at 40° C. by volume ratio HCl:H ₂ O:HNO ₃ (mixed at a ratio of 1:1:0.08) for 2 minutes for etching.

Then, the exposed surface was observed using a scanning electron microscope (SU3500, manufactured by Hitachi High-Technologies Corporation). In the evaluation of the crystal shape, 10 fields of BSE-COMP images in the range of 175 μm×250 μm were randomly taken at 500× magnification to obtain the SEM image of the structure as shown in FIG.

FIG. 1 is an SEM image of the oxide sintered body in Example 1. FIG. In FIG. 1, light-colored crystals are homologous structure compounds, and dark-colored crystals are spinel structure compounds.

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

First, the BSE-COMP image obtained above is drawn along the grain boundaries of the homologous structure compound, and after all drawing is completed, image correction (Image → Adjust → Threshold) is performed, and the spinel structure compound removed. 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 equivalent circle diameter was calculated from the area of each particle obtained. The average values of all particles calculated in 10 fields of view were taken as the average equivalent circle diameter and average aspect ratio of the homologous structure compound (referred to as IGZO phase in Table 1) in the present invention.

Next, the BSE-COMP image obtained above is drawn along the grain boundaries of the spinel structure compound, and after all drawing is completed, image correction (Image → Adjust → Threshold) is performed to obtain a homologous structure. Compounds were removed. 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 equivalent circle diameter was calculated from the area of each particle obtained. The average values of all grains calculated in 10 fields of view were taken as the average equivalent circular diameter and average aspect ratio of the spinel structure compound (referred to as GZO phase in Table 1) in the present invention.

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

It can be seen that the oxide sintered bodies of Examples 1 to 3 all have relative densities 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.

Moreover, it can be seen that the oxide sintered bodies of Examples 1 to 3 all have a resistivity 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.

Further, it can be seen that the oxide sintered bodies of Examples 1 to 3 all have a bending strength of 180 MPa or more. Therefore, according to the embodiment, it is possible to suppress the damage of the oxide sintered body when manufacturing a sputtering target using such an oxide sintered body or when performing sputtering with such a sputtering target. .

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 with high bending strength can be realized.

Further, by comparing Examples 1 to 3 with Comparative Examples 2 and 3, among homologous structure compounds represented by InGaO ₃ (ZnO) _m (m is an integer), homologous structure compounds represented by m being 3 or more It can be seen that the bending strength is reduced due to the inclusion of

Further, Examples 1 to 3 containing a homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ and containing In, Ga and Zn within the ranges shown in the above formulas (1) to (3), In comparison with Comparative Example 4, which does not contain In, Ga, or Zn within these ranges, the specific resistance is reduced to 5.0×10 ⁻¹ Ωcm or less by containing In, Ga, and Zn within these ranges. I understand.

Further, 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 ratio of the spinel structure compound is greater than 80%, the area ratio of the spinel structure compound was 80% or less. It can be seen that the specific resistance is reduced by setting

In addition, in the oxide sintered bodies of Examples 1 to 3, the average area equivalent circle diameter of the homologous structure compound is all 10 μm or less, and the average aspect ratio of the homologous structure compound is 2.0 or less. . As a result, the crystal structure in the oxide sintered body can be refined, so that the bending strength of the oxide sintered body can be improved.

In addition, in the oxide sintered bodies of Examples 1 to 3, the average area equivalent circle diameter of the spinel structure compound is all 5 μm or less, and the average aspect ratio of the spinel structure compound is 2.0 or less. . As a result, the crystal structure in the oxide sintered body can be refined, so that the bending strength of the oxide sintered body can be improved.

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

Next, 10 pieces each of the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 4 were joined to the base material using In solder. As a result, no cracks were found in the oxide sintered bodies of Examples 1 to 3 and Comparative Example 1. On the other hand, 3, 4 and 2 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, and the targets were evaluated from the amount of arcing generated. The oxide sintered bodies of Comparative Examples 1 and 4 had high specific resistance and could not be subjected to DC sputtering.
(Sputtering conditions)
Apparatus: DC magnetron sputtering apparatus, exhaust system cryopump, rotary pump Ultimate vacuum: 3×10 ⁻⁶ Pa
Sputter pressure: 0.4 Pa
Oxygen partial pressure: 1×10 ⁻³ Pa
Input power amount time: 2 W/cm ²
Time: 10 hours (arking counter)
Model: μArc Monitor MAM Genesis MAM Data Collector Ver.2.02
(Manufactured by LANDMARK TECHNOLOGY)
(arcing evaluation)
A: 20 times or less B: 21-50 times C: 51-100 times D: 101 times or more

Moreover, the crack of the oxide sintered body was also confirmed after sputtering. Table 2 shows the above evaluation results.

Examples 1 and 2 where the atomic ratio of each element satisfies the formulas (7) to (9), and Comparative Examples 2 and 3 where the atomic ratio of the atomic ratio of each element does not satisfy the formulas (7) to (9) By comparison, it can be seen that the occurrence of arcing and cracking of the oxide sintered body is reduced when the atomic ratio of each element satisfies the formulas (7) to (9).

Further, by comparing Example 1 where the atomic ratio of each element satisfies the formulas (13) to (15) and Example 2 where the atomic ratio of each element does not satisfy the formulas (13) to (15), each element satisfies formulas (13) to (15), the occurrence of arcing is further reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the embodiments, 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-like shape, and may be any shape such as a cylindrical shape. It may be in shape.

Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments so shown and described. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and equivalents thereof.

Claims (14)

An oxide sintered body composed of indium , gallium , zinc , oxygen, and inevitable impurities ,
The atomic ratio of indium, gallium, and zinc is
0.08<In/(In+Ga+Zn)≦0.19
0.35<Ga/(In+Ga+Zn)<0.58
0.23<Zn/(In+Ga+Zn)<0.46
The filling,
A homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ and a spinel structure compound represented by ZnGa ₂ O ₄ ,
The area ratio of the spinel structure compound represented by ZnGa ₂ O ₄ is 25% or more,
An oxide sintered body having a bending strength of 180 MPa or more. 2. The oxide sintered body according to claim 1, wherein the atomic ratio of each element satisfies the following formula.
0.08<In/(In+Ga+Zn)≦ 0.19
0.40≦Ga/(In+Ga+Zn)<0.58
0.25≦Zn/(In+Ga+Zn)<0.46 3. The oxide sintered body according to claim 1 or 2, wherein 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 oxide sintered body according to any one of claims 1 to 3 , wherein 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 oxide sintered body according to any one of claims 1 to 4 , wherein 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 oxide sintered body according to any one of claims 1 to 5 , wherein the homologous structure compound has an average equivalent circle diameter of 10 µm or less. The oxide sintered body according to any one of claims 1 to 6 , wherein the homologous structure compound has an average aspect ratio of 2.0 or less. The oxide sintered body according to any one of claims 1 to 7, wherein the spinel structure compound has an average area equivalent circle diameter of 5 µm or less. The oxide sintered body according to any one of claims 1 to 8 , wherein the spinel structure compound has an average aspect ratio of 2.0 or less. The oxide sintered body according to any one of claims 1 to 9 , wherein the spinel structure compound has an area ratio of 80% or less. The oxide sintered body according to any one of claims 1 to 10 , which has a relative density of 99.5% or more. The oxide sintered body according to any one of claims 1 to 11 , having a specific resistance of 5.0 × 10 ^-1 Ωcm or less. 13. The oxide sintered body according to claim 1, comprising a homologous structure compound represented by InGaZnO ₄ or InGaZn ₂ O ₅ and a spinel structure compound represented by ZnGa ₂ O ₄ . A sputtering target using the oxide sintered body according to any one of claims 1 to 13 as a target material.

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