TW202006162A - Sintered oxide body, sputtering target and method for producing oxide thin film - Google Patents

Abstract

A sintered oxide body according to an embodiment of the embodiment of the present invention is an oxide sintered body containing indium, gallium, and zinc at a ratio satisfying the following formulas (1) to (3), the oxide sintered body is composed of a single phase crystal phase, and the average particle diameter of the crystal phase is 15.0 μm or less.

0.01≦In/(In+Ga+Zn)<0.20 .. (1)

0.10≦Ga/(In+Ga+Zn)≦0.49 .. (2)

0.50≦Zn/(In+Ga+Zn)≦0.89 .. (3)

Description

Method for manufacturing oxide sintered body, sputtering target and oxide film

The embodiment of the present invention relates to a method for manufacturing an oxide sintered body, a sputtering target, and an oxide thin film.

The sputtering method using the sputtering target thin film formation method is extremely effective as a method for forming a thin film with a large area and high accuracy, and the sputtering method is widely used in display devices such as liquid crystal display devices. In recent years, in the technical field of semiconductor layers such as thin-film transistors (hereinafter also referred to as "TFT"), the oxidation represented by In-Ga-Zn composite oxide (hereinafter also referred to as "IGZO"), which replaces amorphous silicon Attention has been paid to object semiconductors, and the sputtering method has also been utilized in the formation of IGZO thin films (for example, refer to Patent Document 1).

In the above-mentioned sputtering method, problems such as abnormal quality of the formed thin film or cracking of the sputtering target during sputtering may occur due to abnormal discharge or the like. As one of the methods to avoid these problems, there is a method of increasing the density of the sputtering target.

Furthermore, high-density targets may also produce abnormal discharge. For example, when the crystal phase constituting the target is a composite phase, and there is a difference in resistance between different crystal phases, there is a risk of abnormal discharge.

When an IGZO thin film is used in a semiconductor layer of a TFT, its semiconductor characteristics greatly change due to the ratios of In, Ga, and Zn, so various ratios are under review. For example, in Patent Document 2, it is reviewed that the ratio of each metal element becomes In<Ga<Zn. The ratios of In, Ga, and Zn of the IGZO sputtering target can be adjusted appropriately to obtain specific semiconductor characteristics. For example, regarding the IGZO sputtering target, a target showing homologous crystal structures represented by InGaZnO ₄ or In ₂ Ga ₂ ZnO ₇ is under review.

On the other hand, regarding the IGZO sputtering target containing a large amount of Zn, a target composed of a composite phase of a homologous crystal structure and a spinel structure of Ga ₂ ZnO _{4 was} also examined (for example, refer to Patent Document 3).

However, due to the higher resistance of Ga ₂ ZnO ₄ than in the case of homologous crystal structures, the risk of abnormal discharge is higher. Therefore, the sputtering target is preferably a single phase with a homologous crystal structure.

On the other hand, compared to a sputtering target composed of a composite phase, a high-density sputtering target composed of a single phase tends to have a larger crystal grain size. Furthermore, if the crystal grain size is enlarged, the mechanical strength of the sputtering target may be reduced, and cracking may occur during sputtering.

Furthermore, it is also important for the sputtering target to have a uniform distribution of the above characteristics within the sputtering surface. If the density and the like are unevenly distributed in the plane, abnormal discharge may occur or cracking may occur during sputtering. In the IGZO sputtering target, the unevenness of the characteristic distribution of the sputtering surface may appear in the form of color difference.

[Prior Technical Literature] [Patent Literature]

Patent Literature 1: Japanese Patent Laid-Open No. 2007-73312

Patent Document 2: Japanese Patent Application Publication No. 2017-145510

Patent Document 3: Japanese Patent Laid-Open No. 2008-163441

One aspect of the embodiment of the present invention was created in view of the above-mentioned circumstances, and aims to provide a sputtering target capable of stably performing sputtering and an oxide sintered body for manufacturing the sputtering target.

An aspect of an embodiment of the present invention is an oxide sintered body containing indium, gallium, and zinc in a ratio satisfying the following formulas (1) to (3), the oxide sintering system is composed of a single-phase crystal phase, and The average particle diameter of the aforementioned crystal phase is 15.0 μm or less.

0.01≦In/(In+Ga+Zn)<0.20‧‧(1)

0.10≦Ga/(In+Ga+Zn)≦0.49‧‧(2)

0.50≦Zn/(In+Ga+Zn)≦0.89‧‧(3)

According to one aspect of the embodiment of the present invention, sputtering can be performed stably.

Fig. 1 is an SEM image (50 times) of the oxide sintered body in Example 1.

FIG. 2 is an SEM image (500 times) of the oxide sintered body in Example 1. FIG.

Figure 3 is an SEM image (500 times) of the oxide sintered body in Comparative Example 2.

FIG. 4 is an X-ray diffraction diagram of the oxide sintered body in Example 1. FIG.

Figure 5 compares the X-ray diffraction pattern of the oxide sintered body in Example 1 with the peak positions of the X-ray diffraction patterns of InGaZnO ₄ , In ₂ Ga ₂ ZnO ₇ and Ga ₂ ZnO ₄ Figure.

Hereinafter, an embodiment of the method for manufacturing an oxide sintered body, a sputtering target, and an oxide thin film disclosed in the present invention will be described with reference to the accompanying drawings. In addition, the present invention is not limited by the embodiments shown below.

The oxide sintering system of the embodiment contains an oxide sintered body of indium (In), gallium (Ga), and zinc (Zn), and can be used as a sputtering target.

The oxide sintering system of the embodiment is composed of a single-phase crystal phase, and the average particle diameter of the crystal phase is 15.0 μm or less. Thereby, the flexural strength of the oxide sintered body can be improved. Furthermore, when the oxide sintered body is polished, it is possible to suppress the surface roughness by peeling off the large particles on the surface, so it is easy to obtain a smooth surface.

In addition, the oxide sintered body of the embodiment preferably has an average particle size of 10.0 μm or less, more preferably 8.0 μm or less, still more preferably 6.0 μm or less, and even more preferably 5.0 μm or less. In addition, the lower limit of the average particle diameter is not particularly limited, but it is usually 1.0 μm or more.

Furthermore, the oxide sintering system is composed of a single-phase crystalline phase, so that the elements in the oxide sintering body can be evenly distributed. Therefore, according to the embodiment, each element in the film of the oxide semiconductor thin film formed by sputtering can be uniformly distributed.

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

0.01≦In/(In+Ga+Zn)<0.20‧‧(1)

0.10≦Ga/(In+Ga+Zn)≦0.49‧‧(2)

0.50≦Zn/(In+Ga+Zn)≦0.89‧‧(3)

Thereby, a semiconductor layer suitable for using TFT can be obtained.

In addition, the atoms of the elements of the oxide sintering system of the embodiment preferably satisfy the following formulas (4) to (6),

0.05≦In/(In+Ga+Zn)≦0.15‧‧(4)

0.15≦Ga/(In+Ga+Zn)≦0.45‧‧(5)

0.50≦Zn/(In+Ga+Zn)≦0.80‧‧(6)

The atomic ratio of each element is more preferable to satisfy the following formulas (7) to (9).

0.05≦In/(In+Ga+Zn)≦0.15‧‧(7)

0.20≦Ga/(In+Ga+Zn)≦0.40‧‧(8)

0.50≦Zn/(In+Ga+Zn)≦0.70‧‧(9)

Furthermore, the oxide sintered body of the embodiment may contain unavoidable impurities derived from raw materials and the like. The unavoidable 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, respectively.

In addition, it is preferable that the single-phase crystal phase constituting the oxide sintered body of the embodiment is observed with diffraction peaks in the following regions A to P in the graph obtained by X-ray diffraction measurement (CuKα ray).

A. 24.5° to 26.0°

B. 31.0° to 32.5°

C. 32.5° to 33.2°

D. 33.2° to 34.0°

E. 34.5° to 35.7°

F. 35.7° to 37.0°

G. 38.0° to 39.2°

H. 39.2° to 40.5°

I. 43.0° to 45.0°

J. 46.5° to 48.5°

K. 55.5° to 57.8°

L. 57.8° to 59.5°

M. 59.5° to 61.5°

N. 65.5° to 68.0°

O. 68.0° to 69.0°

P. 69.0° to 70.0°

Thereby, when the oxide sintered body is used as a sputtering target, abnormal discharge can be suppressed. Therefore, according to the embodiment, the generation of particles due to the abnormal discharge described above can be suppressed, so that the production yield of the TFT can be improved.

Furthermore, the oxide sintered body of the embodiment preferably has a relative density of 97.0% or more. Therefore, when the oxide sintered body is used as a sputtering target, the discharge state of DC sputtering can be stabilized. In addition, the oxide sintered body of the embodiment is preferably a relative density of 98.0% or more, and a relative density of 99.0% or more.

When an oxide sintered body having a relative density of 97.0% or more is used as a sputtering target, voids in the sputtering target can be reduced, and gas components in the atmosphere can be easily prevented from infiltrating. Furthermore, during sputtering, defects such as abnormal discharge due to the above-mentioned voids and cracking of the sputtering target are unlikely to occur.

In addition, the flexural strength of the oxide sintered body of the embodiment is preferably 40 MPa or more. Accordingly, when the sputtering target is manufactured using the oxide sintered body or when the sputtering target is sputtered, damage to the oxide sintered body can be suppressed.

In addition, the flexural strength of the oxide sintered body of the embodiment is preferably 50 MPa or more, more preferably 60 MPa or more, and still more preferably 70 MPa or more. In addition, the upper limit of the flexural strength is not particularly limited, but is usually 300 MPa or less.

In addition, the oxide sintered body used in the sputtering target of the embodiment preferably has a maximum surface roughness height Ry of 15.0 μm or less. Thereby, when sputtering is performed using the above sputtering target, nodule generation on the target surface can be suppressed.

In addition, the oxide sintered body used in the sputtering target of the embodiment has a maximum height Ry of preferably 11.0 μm or less, and more preferably 10.0 μm or less. In addition, the lower limit of the maximum height Ry is not particularly limited, but is usually 0.1 m or more.

Furthermore, the oxide sintered body of the embodiment preferably has a specific resistance of 40 mΩ·cm or less. Therefore, when the oxide sintered body is used as a sputtering target, sputtering can be performed using a low-cost DC power supply, and the film forming rate can be improved. Furthermore, this can suppress the occurrence of abnormal discharge.

In addition, the oxide sintered body of the embodiment preferably has a specific resistance of 35 mΩ‧cm or less, and more preferably a specific resistance of 30 mΩ‧cm or less. In addition, the lower limit of the specific resistance is not particularly limited, but it is usually 0.1 mΩ‧cm or more.

In addition, regarding the sputtering target of the embodiment, the color difference ΔE* on the surface of the sputtering target is preferably 10 or less. Furthermore, the color difference ΔE* in the depth direction of the sputtering target is preferably 10 or less. When this value satisfies the above conditions, it is suitable as a sputtering target because the crystal grain size and composition are not biased.

In addition, in the sputtering target of the embodiment, the color difference ΔE* of the entire surface and the depth direction is preferably 9 or less, and the color difference ΔE* is 8 or less.

<Each manufacturing step of oxide sputtering target>

The oxide sputtering target of the embodiment can be produced by, for example, the method shown below. First, mix the raw material powder. 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 that the oxide sintered body becomes a desired ratio of constituent elements.

Each raw material powder is preferably dry mixed beforehand. The above-mentioned dry mixing method is not particularly limited, and various mixing machines such as a container rotary mixer and a container fixed mixer can be used for mixing. Among them, since shear force and impact force can be applied to the raw material powder to perform high-speed dispersion and mixing, mixing with a high-speed mixer such as EARTHTECHNICA Co., Ltd. is preferred. By performing a dry mixing process in advance in this way to uniformly disperse and mix the raw material powders, it is easy to obtain a single-phase structure sintered body, and the color difference is within the aforementioned range, which is preferable.

Examples of the method for manufacturing a molded body from the mixed powder thus mixed include a slip casting method, a CIP (Cold Isostatic Pressing) method, and the like. Next, two specific methods will be described for specific examples of the forming method.

(Grouting method)

The grouting method described here is to prepare a slurry containing mixed powders and organic additives using a dispersion medium, inject the slurry into a mold and remove the dispersion medium, thereby forming. The organic additives usable here are well-known adhesives, dispersants, and the like.

In addition, the dispersion medium used when preparing the slurry is not particularly limited, and can be appropriately selected from water, alcohols, etc. according to the purpose. In addition, the method of preparing the slurry is not particularly limited. For example, a ball mill can be used in which a mixed powder, an organic additive, and a dispersion medium are fed into a pot and mixed. The slurry thus obtained is poured into a mold, the dispersion medium is removed, and a molded body is produced. The molds that can be used here are metal molds, gypsum molds, resin molds that are pressurized to remove the dispersion medium, and the like.

(CIP method)

In the CIP method described here, a slurry containing mixed powders and organic additives is prepared using a dispersion medium, and after spray drying the slurry, the resulting dry powder is filled in a mold to perform pressure molding . The organic additives usable here are well-known adhesives, dispersants, and the like.

In addition, the dispersion medium used when preparing the slurry is not particularly limited, and can be appropriately selected from water, alcohols, etc. according to the purpose. In addition, the method of preparing the slurry is not particularly limited. For example, a ball mill can be used in which a mixed powder, an organic additive, and a dispersion medium are placed in a tank and mixed.

The slurry thus obtained was spray-dried to prepare a dry powder having a moisture content of 1% or less, and the dry powder was filled into a mold and subjected to pressure molding by the CIP method to produce a molded body.

Next, the obtained molded body is fired to produce a sintered body. The firing furnace for producing the sintered body is not particularly limited, and a firing furnace that can be used for producing a ceramic sintered body can be used.

The firing temperature is 1350°C to 1580°C, preferably 1400°C to 1550°C, and more preferably 1450°C to 1550°C. The higher the firing temperature, the more high-density sintered body can be obtained. On the other hand, from the viewpoint of suppressing the enlargement of the sintered body structure and preventing cracking, it is preferably controlled to be below the above temperature. In addition, when the firing temperature does not reach 1350°C, it is difficult to form a single-phase crystal phase, which is not preferable.

Next, the obtained sintered body is subjected to cutting processing. The above-mentioned cutting process is performed using a flat grinding disk or the like. Furthermore, the maximum height Ry of the surface roughness after cutting can be appropriately controlled by selecting the grinding particle size of the whetstone used for cutting, but if the particle size of the sintered body is enlarged, it will be due to hypertrophy The particles peel off and the maximum height Ry increases.

The sputter target is produced by joining the cut sintered body and the substrate. The material of the base material can be appropriately selected from stainless steel, copper, titanium, etc. As the bonding material, low melting point solder such as indium can be used.

[Example]

[Example 1]

The average particle diameter In 0.6μm ₂ O ₃ powder of an average particle size of 1.5μm Ga ₂ O ₃ powder and ZnO powder of an average particle size of 0.8μm in a high speed mixer EARTHTECHNICA Co., Ltd. The dry-mixed, Prepare a mixed powder.

In addition, the average particle size of the raw material powder was measured using a particle size distribution measuring device HRA manufactured by Nikkiso Co., Ltd. In the above measurement, water was used as the solvent, and the refractive index of the measurement substance was set to 2.20 for measurement. In addition, the average particle diameter of the raw material powder described below was also set to the same measurement condition. In addition, the average particle diameter of the raw material powder is the volume cumulative particle diameter D50 of 50% by volume of the cumulative volume by the laser diffraction scattering particle size distribution measurement method.

In addition, when preparing the mixed powder, the atomic ratio of the metal elements contained in all the raw material powders is In/(In+Ga+Zn)=0.1, Ga/(In+Ga+Zn)=0.3, Zn/ (In+Ga+Zn)=0.6, mix each raw material powder.

Next, in a tank prepared with mixed powder, an adhesive of 0.2% by mass with respect to the mixed powder, a dispersant with 0.6% by mass with respect to the mixed powder, and 20% by mass of water with respect to the mixed powder were added to perform ball mill mixing And prepare the slurry.

Next, the prepared slurry is injected into a metal mold sandwiched with a filter, and drained to obtain a molded body. Next, this molded body is fired to produce a sintered body. The firing is performed at a firing temperature of 1500°C, a firing time of 10 hours, a temperature increase rate of 100°C/hour, and a temperature decrease rate of 100°C/hour.

Next, the obtained sintered body was subjected to cutting processing to obtain a sputtering target having a width of 210 mm×a length of 710 mm×a thickness of 6 mm. In addition, #170's whetstone is used in the cutting process.

[Examples 2 to 3]

The sputtering target was obtained by the same method as Example 1. In addition, in Examples 2 to 3, when preparing the mixed powder, each raw material powder was prepared so that the atomic ratio of the metal element contained in all the raw material powders became the atomic ratio described in Table 1.

[Comparative Examples 1 to 3]

In Comparative Examples 1 to 3, when preparing the mixed powder, the atomic ratio of the metal elements contained in all the raw material powders was In/(In+Ga+Zn)=0.1, Ga/(In+Ga+Zn )=0.3, Zn/(In+Ga+Zn)=0.6 to prepare each raw material powder. In addition, the firing temperature was performed so as to be the temperature described in Table 1, and in Comparative Example 2, dry mixing was not performed. Other than this, the same method as in Example 1 was used to obtain a sputtering target.

In addition, in Examples 1 to 3 and Comparative Examples 1 to 3, it was confirmed that the atomic ratio of each metal element measured when preparing each raw material powder was equivalent to the atomic ratio of each metal element in the obtained oxide sintered body. The atomic ratio of each metal element in the oxide sintered body is measured by, for example, ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy: Inductively Coupled Plasma Atomic Emission Spectroscopy).

Next, with respect to the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above, relative density was measured. The relative density is based on the Archimedes Method.

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

In addition, the said theoretical density ρ(g/cm ³ ) is calculated from the mass% and density of the raw material powder used for manufacturing an oxide sintered body. Specifically, it is calculated by the following formula (10).

ρ={(C ₁ /100)/ρ ₁ +(C ₂ /100)/ρ ₂ +(C ₃ /100)/ρ ₃ } ^-1 ‧‧(10)

In addition, C ₁ to C ₃ and ρ ₁ to ρ ₃ in the above formulae show the following values, respectively.

‧C ₁ : mass% of In ₂ O ₃ powder used in the production of oxide sintered body

‧Ρ ₁ : In ₂ O ₃ density (7.18g/cm ³ )

‧C ₂ : mass% of Ga ₂ O ₃ powder used in the production of oxide sintered body

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

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

‧Ρ ₃ : Density of ZnO (5.60g/cm ³ )

Next, the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above were measured for specific resistance (bulk resistance), respectively.

Specifically, it uses Loresta (registered trademark) HP MCP-T410 (in-line 4-probe probe TYPE ESP) manufactured by Mitsubishi Chemical Corporation, and abuts the probe on the surface of the processed oxide sintered body, and AUTO RANGE mode measurement. The measurement points were 5 points in the vicinity of the center of the oxide sintered body and 4 corners, and the average value of the measured values was taken as the volume resistance value of the sintered body.

Next, the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above were respectively measured for flexural strength. The above-mentioned flexural strength is the use of a sample piece (36 mm in total length, 4.0 mm in width, 3.0 mm in thickness) cut out from the oxide sintered body by wire cutting electrical discharge machining, and is based on JIS-R-1601 (precision ceramics) The flexural strength test method) was measured by the three-point flexural strength measurement method.

Here, regarding the above Examples 1 to 3 and Comparative Examples 1 to 3, the atomic ratio of each element contained in the powder mixture and whether there is dry mixing, firing temperature, oxide sintered body when manufacturing the oxide sintered body The measurement results of the relative density, specific resistance (bulk resistance) and flexural strength are shown in Table 1.

[Table 1]

It is known that the relative densities of the oxide sintered bodies of Examples 1 to 3 are all 97.0% or more. Therefore, according to the embodiment, when the oxide sintered body is used as a sputtering target, the discharge state of DC sputtering can be stabilized.

Furthermore, it is known that the specific resistances of the oxide sintered bodies of Examples 1 to 3 are all 40 mΩcm or less. Therefore, according to the embodiment, when the above-mentioned oxide sintered body is used as a sputtering target, sputtering using a low-cost DC power source becomes possible, and the film forming rate can be improved.

Furthermore, it is known that the oxide sintered bodies of Examples 1 to 3 have a flexural strength of 40 MPa or more. Therefore, according to the embodiment, when the sputtering target is manufactured using the above-mentioned oxide sintered body or when sputtering is performed with the above-mentioned sputtering target, damage to the oxide sintered body can be suppressed.

Next, the sputtering target surfaces of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above were observed using a scanning electron microscope (SEM: Scanning Electron Microscope), and the average particle diameter of the crystal was measured.

Specifically, the oxide sintered body is cut, and the resulting cut surface is polished in stages using emery paper #180, #400, #800, #1000, #2000, and finally polished and polished to complete the processing For the mirror.

After that, the etching solution at 40°C [the 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 a volume ratio of HCl:H ₂ O: HNO ₃ =1: 1: 0.08 ratio] immersion for 2 minutes to perform etching.

Then, the presented surface was observed using a scanning electron microscope (SU3500, manufactured by Hitachi High-Technologies Co., Ltd.). In addition, in the measurement of the average particle size, the BSE-COMP images of ten fields of view of 175 μm×250 μm were randomly taken at a magnification of 500 times to obtain an SEM image of the tissue.

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

First, the image is drawn along the grain boundary. After all the images are drawn, image correction (Image→Adjust→Threshold) is performed. After image correction, residual noise is removed as necessary (Process→Noise→Despeckle).

After that, particle analysis (Analyze→Analyze Particles) is performed, and the area of each particle is obtained, and then the diameter of the equal area circle is calculated. The average diameter of the equal-area circle diameters of all particles calculated in ten fields of view is taken as the average particle diameter of the present invention.

Figures 1 and 2 are SEM images of the oxide sintered body in Example 1. In addition, in FIGS. 1 and 2, the black portion is a portion that is missing through surface polishing. As shown in FIGS. 1 and 2, it can be seen that the oxide sintering system of Example 1 is composed of a single-phase crystal phase.

Figure 3 is an SEM image of the oxide sintered body in Comparative Example 2. In addition, in Fig. 3, the black portion is the in poor phase (In poor phase). As shown in FIG. 3, it can be seen that the oxide sintering system of Comparative Example 2 is composed of a composite phase crystal phase.

Next, the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above were subjected to X-ray diffraction (X-Ray Diffraction: XRD) measurement to obtain X-ray diffraction patterns.

In addition, the specific measurement conditions of the X-ray diffraction measurement described above are as follows.

‧Device: SmartLab (Rigaku Co., Ltd., registered trademark)

‧Line source: CuKα rays

‧Tube voltage: 40kV

‧Tube current: 30mA

‧Scanning speed: 5deg/min

‧Step: 0.02deg

‧Scanning range: 2θ=20° to 70°

FIG. 4 is an X-ray diffraction diagram of the oxide sintered body in Example 1. FIG. As shown in Fig. 4, in the X-ray diffraction diagram of Example 1, a diffraction spectrum peak was observed in the area of A to P below in the range of the diffraction angle 2θ of 20° to 70°.

A. 24.5° to 26.0°

B. 31.0° to 32.5°

C. 32.5° to 33.2°

D. 33.2° to 34.0°

E. 34.5° to 35.7°

F. 35.7° to 37.0°

G. 38.0° to 39.2°

H. 39.2° to 40.5°

I. 43.0° to 45.0°

J. 46.5° to 48.5°

K. 55.5° to 57.8°

L. 57.8° to 59.5°

M. 59.5° to 61.5°

N. 65.5° to 68.0°

O. 68.0° to 69.0°

P. 69.0° to 70.0°

As described above, the oxide sintering system of Example 1 is composed of a single-phase crystalline phase. Therefore, it can be seen that the diffraction spectrum peaks observed in the regions A to P are caused by the single-phase crystalline phase. In other words, from the graph obtained by X-ray diffraction measurement, the single-phase crystal phase constituting the oxide sintered body of Example 1 can be identified.

FIG. 5 is a graph comparing the peak positions of the X-ray diffraction patterns of the oxide sintered body of Example 1 with the X-ray diffraction patterns of InGaZnO ₄ , In ₂ Ga ₂ ZnO _7, and Ga ₂ ZnO ₄ .

As shown in FIG. 5, it can be seen that the single-phase crystal phase constituting the oxide sintered body of Example 1 can be different from the known crystal phases (here InGaZnO ₄ , In ₂ Ga ₂ ZnO ₇ and Ga ₂ ZnO ₄ ) Diffraction peaks were observed at the peak position. Among them, "known crystalline phase" means "the crystalline phase where the peak position of the X-ray diffraction pattern is registered in the JCPDS (Joint Committee of Powder Diffraction Standards) card".

That is, it can be seen that the single-phase crystal phase constituting the oxide sintered body of Example 1 is a crystal phase unknown before.

Next, with respect to the sputtering targets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 obtained above, the maximum height Ry of the surface roughness was measured, respectively. Specifically, the maximum height Ry of the sputtering surface is measured using a surface roughness measuring device (SJ-210/Mitutoyo Corporation). Measure the 10 positions of the sputtering surface, and set the maximum value as the maximum height Ry of the sputtering target. Table 2 shows the measurement results.

Next, the color difference ΔE* in the surface and the color difference ΔE* in the depth direction were measured on the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above, respectively. The "color difference ΔE*" is an index that digitizes the difference between two colors.

The maximum chromatic aberration ΔE* in the above-mentioned surface is measured on the surface of the sputter target after cutting at 50 mm intervals in the x-axis and y-axis directions using a color difference meter (manufactured by KONICA MINOLTA, color-color difference meter CP-300) , The L value, a value and b value of each measured point are evaluated in CIE1976 space. Then, from the difference ΔL, Δa, Δb of the L value, a value, and b value of two points among the measured points, the color difference ΔE* of all combinations of two points is obtained by the following formula (11), and The maximum value of the plurality of color differences ΔE* obtained is set as the maximum color difference ΔE* in the surface.

ΔE*=((ΔL) ² +(Δa) ² +(Δb) ² ) ^1/2 ‧‧(11)

In addition, the maximum color difference ΔE* in the depth direction is to cut 0.5 mm at any place of the sputter target after cutting, and measure each depth up to the center of the sputter target using a color difference meter. The L value, a value and b value of the points are evaluated in CIE1976 space. Then, the color difference ΔE* of all combinations of two points is obtained from the difference between the L value, a value, and b value of two of the measured points, ΔL, Δa, and Δb, and the maximum value of the plurality of color differences ΔE* is obtained. The value is set to the maximum color difference ΔE* in the depth direction.

Here, in order to evaluate the target from the amount of arc (abnormal discharge) generated, the sputter targets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were bonded to copper using indium which is a low-melting solder as a bonding material Substrate.

Next, sputtering was performed using the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3, and the target was evaluated from the amount of arc (abnormal discharge) generated. The evaluation results are shown in Table 2.

(Arc Assessment)

A: Very little.

B: Many.

C: Very much.

Here, for the above Examples 1 to 3 and Comparative Examples 1 to 3, the atomic ratio of each element contained in the powder mixture, the crystal phase of the oxide sintered body used for the sputtering target, the average particle diameter, and the surface roughness The measurement results of the maximum height Ry of the degree, the maximum color difference ΔE* in the in-plane direction, the maximum color difference ΔE* in the depth direction, and the arc evaluation are shown in Table 2.

[Table 2]

It is known that the crystal phases of the oxide sintered bodies of Examples 1 to 3 are all composed of a single phase. Therefore, according to the embodiment, as can be seen from the results of arc evaluation, when the oxide sintered body is used as a sputtering target, sputtering can be stably performed.

Furthermore, it is known that the average particle diameters of the oxide sintered bodies of Examples 1 to 3 are all 15.0 μm or less. Therefore, according to the embodiment, when the above-mentioned oxide sintered body is subjected to polishing, it is possible to suppress the coarsening of the surface by peeling off large crystal grains from the surface.

Furthermore, it is known that the maximum height Ry of the surface roughness of the oxide sintered bodies of the sputtering targets of Examples 1 to 3 is all 15.0 μm or less. Therefore, according to the embodiment, the occurrence of protrusions on the target surface can be suppressed when sputtering is performed.

It is known that the maximum color difference ΔE* in the in-plane direction and the depth direction of the sputtering targets of Examples 1 to 3 is 10 or less. Therefore, according to the embodiment, since the crystal grain size and composition are unbiased, it is suitable as a sputtering target.

The above is the description of the embodiments of the present invention, but the present invention is not limited to the above embodiments, and various changes can be made as long as they do not deviate from the gist of the present invention. For example, the embodiment shows an example in which a plate-shaped oxide sintered body is used as a sputtering target, but the shape of the oxide sintered body is not limited to a plate shape, and may be any shape such as a cylindrical shape.

Further effects and modifications can be easily derived by those with ordinary knowledge in the technical field. Accordingly, the broader aspect of the present invention is not limited to the specific details and representative embodiments described and described above. Therefore, various changes can be made without departing from the spirit or scope of the broad invention concept defined by the appended patent application scope and its equivalents.

Claims (11)

An oxide sintered body containing indium, gallium and zinc in a ratio satisfying the following formulas (1) to (3), The oxide sintering system is composed of a single-phase crystalline phase, and in the figure obtained by X-ray diffraction measurement (CuKα ray), diffraction peaks are observed in the following regions A to P; 0.01≦In/(In+Ga+Zn)<0.20‧‧(1) 0.10≦Ga/(In+Ga+Zn)≦0.49‧‧(2) 0.50≦Zn/(In+Ga+Zn)≦0.89‧‧(3); A. 24.5° to 26.0° B. 31.0° to 32.5° C. 32.5° to 33.2° D. 33.2° to 34.0° E. 34.5° to 35.7° F. 35.7° to 37.0° G. 38.0° to 39.2° H. 39.2° to 40.5° I. 43.0° to 45.0° J. 46.5° to 48.5° K. 55.5° to 57.8° L. 57.8° to 59.5° M. 59.5° to 61.5° N. 65.5° to 68.0° O. 68.0° to 69.0° P. 69.0° to 70.0°. The oxide sintered body as described in item 1 of the scope of patent application contains indium, gallium and zinc in a ratio satisfying the following formulas (4) to (6); 0.05≦In/(In+Ga+Zn)≦0.15‧‧(4) 0.15≦Ga/(In+Ga+Zn)≦0.45‧‧(5) 0.50≦Zn/(In+Ga+Zn)≦0.80‧‧(6) The oxide sintered body as described in item 1 or 2 of the scope of patent application contains indium, gallium and zinc at a ratio satisfying the following formulas (7) to (9); 0.05≦In/(In+Ga+Zn)≦0.15‧‧(7) 0.20≦Ga/(In+Ga+Zn)≦0.40‧‧(8) 0.50≦Zn/(In+Ga+Zn)≦0.70‧‧(9). The oxide sintered body according to any one of claims 1 or 2, wherein the average particle diameter of the crystal phase is 15.0 μm or less. The oxide sintered body as described in item 1 or 2 of the patent application, wherein the relative density is 97.0% or more. The oxide sintered body as described in item 1 or 2 of the patent application, wherein the flexural strength is 40 MPa or more. The oxide sintered body as described in item 1 or 2 of the patent application, wherein the specific resistance is 40 mΩcm or less. A sputtering target includes the oxide sintered body described in item 1 or 2 of the patent application. The sputtering target as described in item 8 of the patent application, wherein the maximum height Ry of the surface roughness is 15.0 μm or less. The sputtering target as described in item 8 of the patent application, wherein the color difference ΔE* is 10 or less. A method for manufacturing an oxide thin film is to sputter the sputtering target described in item 8 of the patent application and form a film.

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