KR20200097197A - Oxide sintered body, sputtering target, and manufacturing method of oxide thin film - Google Patents

Abstract

The oxide sintered body according to one aspect of the embodiment is an oxide sintered body containing indium, gallium, and zinc in a ratio satisfying the following formulas (1) to (3), and is composed of a single-phase crystal phase, and the average particle diameter of the crystal phase It is 15.0 micrometers or less.

Description

Oxide sintered body, sputtering target, and manufacturing method of oxide thin film

The disclosed embodiment relates to a method for producing an oxide sintered body, a sputtering target, and an oxide thin film.

The sputtering method, which is a method of forming a thin film using a sputtering target, is very effective as a method of forming a thin film with a large area and with high accuracy, and the sputtering method is widely used in display devices such as liquid crystal displays. In recent years, in the technical field of semiconductor layers such as thin film transistors (hereinafter, referred to as ``TFT''), an oxide semiconductor represented by an In-Ga-Zn composite oxide (hereinafter also referred to as ``IGZO'') instead of amorphous silicon has attracted attention. , The sputtering method is also utilized for the formation of the IGZO thin film (see, for example, Patent Document 1).

In such a sputtering method, when abnormal discharge or the like occurs, problems such as an abnormality in the quality of the formed thin film and occurrence of cracks in the sputtering target during sputtering may occur. One of the ways to avoid such problems is to densify the sputtering target.

Further, even with a high-density target, abnormal discharge may occur. For example, if the crystal phase constituting the target is a multiple phase, and there is a difference in resistance between different crystal phases, there is a risk of abnormal discharge.

In the case of using an IGZO thin film for the semiconductor layer of a TFT, the semiconductor characteristics change greatly depending on the ratio of In, Ga, and Zn, and various ratios are being studied. For example, in Patent Document 2, the ratio at which the ratio of each metal element becomes In<Ga<Zn is examined. The ratio of In, Ga, and Zn of the IGZO sputtering target can be appropriately adjusted so as to obtain predetermined semiconductor properties. For example, as an IGZO sputtering target, a target showing a homologous crystal structure represented by InGaZnO ₄ or In ₂ Ga ₂ ZnO ₇ has been studied.

On the other hand, in the IGZO sputtering target containing a large amount of Zn, a target composed of a homologous crystal structure and a spinel structure of Ga ₂ ZnO ₄ is also studied (see, for example, Patent Document 3).

However, Ga ₂ ZnO ₄ has a high resistance compared to a homologous crystal structure and the like, and thus there is a high risk of occurrence of abnormal discharge. Therefore, it is preferable that it is a single phase of a homologous crystal structure as a sputtering target.

On the other hand, a high-density sputtering target composed of a single phase tends to have an enlarged crystal grain size compared to a sputtering target composed of a multi-phase. In addition, when the crystal grain size becomes enlarged, the mechanical strength of the sputtering target decreases, and cracks may occur during sputtering.

It is also important that the sputtering target has a uniform distribution of the characteristics within the sputtering surface. If the distribution of density or the like is uneven within the plane, abnormal discharge may occur or cracks during sputtering may occur. In the case of an IGZO sputtering target, the non-uniformity of the characteristic distribution of the sputtering surface may appear as shade of color difference.

Japanese Patent Publication No. 2007-73312 Japanese Patent Publication No. 2017-145510 Japanese Patent Publication No. 2008-163441

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

The oxide sintered body according to an aspect of the embodiment is an oxide sintered body containing indium, gallium, and zinc in a ratio satisfying the following formulas (1) to (3), and is composed of a single-phase crystal phase, and the average particle diameter of the crystal phase It is 15.0 micrometers or less.

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

1 is an SEM image (50 times) of an oxide sintered body in Example 1. FIG.
2 is an SEM image (500 times) of the oxide sintered body in Example 1. FIG.
3 is an SEM image (500 times) of the oxide sintered body in Comparative Example 2. FIG.
4 is an X-ray diffraction chart of an oxide sintered body in Example 1. FIG.
FIG. 5 is a diagram comparing the X-ray diffraction chart of the oxide sintered body in Example 1 with the peak positions in the X-ray diffraction chart of InGaZnO ₄ , In ₂ Ga ₂ ZnO ₇ and Ga ₂ ZnO ₄ .

Hereinafter, an embodiment of a method for producing an oxide sintered body disclosed in the present application, a sputtering target, and an oxide thin film 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 is an oxide sintered body containing indium (In), gallium (Ga), and zinc (Zn), and can be used as a sputtering target.

The oxide sintered body 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, it is possible to increase the transverse strength of such an oxide sintered body. In addition, when grinding such an oxide sintered body, it is easy to obtain a smooth surface because it is possible to suppress the surface roughness due to the peeling of the enlarged particles on the surface.

Further, the oxide sintered body of the embodiment preferably has an average particle diameter 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 determined, but is usually 1.0 µm or more.

Further, since such an oxide sintered body is composed of a single-phase crystal phase, the distribution of each element in the oxide sintered body can be made uniform. Therefore, according to the embodiment, the distribution of each element in the film of the oxide semiconductor thin film formed by sputtering can be made uniform.

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

Thereby, a semiconductor layer suitable for use in a TFT is obtained.

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),

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

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

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 such an oxide sintered body is used for a sputtering target, occurrence of abnormal discharge can be suppressed. Therefore, according to the embodiment, since the generation of particles due to such abnormal discharge can be suppressed, the production yield of the TFT can be improved.

In addition, it is preferable that the relative density of the oxide sintered body of the embodiment is 97.0% or more. Thereby, when such an oxide sintered body is used as a sputtering target, the discharge state of DC sputtering can be stabilized. In addition, it is more preferable that the relative density of the oxide sintered compact of the embodiment is 98.0% or more, and still more preferably 99.0% or more.

When the relative density is 97.0% 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 introduction of gas components into the atmosphere. In addition, during sputtering, abnormal discharges, cracks in the sputtering target, and the like with such voids as a starting point become difficult to occur.

In addition, it is preferable that the sintering strength of the oxide sintered body of the embodiment is 40 MPa or more. Thereby, when a sputtering target is manufactured using such an oxide sintered body, or when sputtering is performed with such a sputtering target, it is possible to suppress damage to the oxide sintered body.

Moreover, it is more preferable that it is 50 MPa or more, and, as for the oxide sintered compact of embodiment, it is still more preferable that it is 60 MPa or more, and it is still more preferable that it is 70 MPa or more. In addition, although the upper limit of the transverse strength is not specifically determined, it is usually 300 MPa or less.

In addition, it is preferable that the maximum height Ry of the surface roughness of the oxide sintered body used for the sputtering target of the embodiment is 15.0 µm or less. Thereby, when sputtering using such a sputtering target, generation of nodules on the target surface can be suppressed.

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

In addition, it is preferable that the oxide sintered body of the embodiment has a specific resistance of 40 mΩ·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. Moreover, by this, it is possible to suppress the occurrence of abnormal discharge.

Moreover, it is more preferable that the specific resistance of the oxide sintered body of the embodiment is 35 mΩ·cm or less, and further preferably 30 mΩ·cm or less. In addition, the lower limit of the specific resistance is not particularly determined, but is usually 0.1 mΩ·cm or more.

In addition, it is preferable that the sputtering target of the embodiment has a color difference ΔE ^* of 10 or less on the surface of the sputtering target. In addition, the degree of depth of the sputtering target color difference ΔE ^* is preferably 10 or less. When this numerical value satisfies the above conditions, it is suitable as a sputtering target because there is no bias in the crystal grain size or composition.

In addition, the sputtering target of the embodiment, a color difference ΔE of the total surface to the depth direction, and ^* is more preferably not more than 9, and more preferably a color difference ΔE ^* of not more than 8.

<Each manufacturing process of the oxide sputtering target>

The oxide sputtering target of the embodiment can be produced, for example, by a method described below. First, the raw material powder is mixed. As the raw material powder, it 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.

It is preferable to dry-mix each raw material powder beforehand. There is no restriction|limiting in particular in such a dry mixing method, It can mix using various mixers, such as a container rotation type mixer and a container fixed type mixer. Among them, it is preferable to mix it with, for example, a high-speed mixer manufactured by Astechnica Co., Ltd. from the viewpoint that high-speed dispersion and mixing can be performed by applying shearing force and impact force to the raw material powder. By performing the dry mixing treatment in advance in this way, if the raw material powder is uniformly dispersed and mixed, it is easy to obtain a sintered body having a single phase structure, and the color difference is preferably within the above-described range.

As a method of producing a molded article from the mixed powder thus mixed, for example, a slip casting method, a CIP (Cold Isostatic Pressing: Cold Isostatic Pressing Method), and the like 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 depending on the purpose, it can be appropriately selected from water, alcohol, and the like. In addition, the method of preparing the slurry is also not particularly limited, and for example, ball mill mixing in which a mixed powder, an organic additive, and a dispersion medium are placed in a pot and mixed can be used. The thus obtained slurry 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 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 into a mold to perform pressure 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 depending on the purpose, it can be appropriately selected from water, alcohol, and the like. Also, there is no particular limitation on the method of preparing the slurry, 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 can 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 a sintering furnace for producing such a sintered body, and a sintering 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. While the higher the firing temperature is, the higher the sintered body is obtained, while it is preferable to control the temperature below the above temperature from the viewpoint of suppressing the enlargement of the structure of the sintered body and preventing cracking. Further, if the firing temperature is less than 1350°C, it becomes difficult to form a single-phase crystal phase, which is not preferable.

Next, the obtained sintered body is cut. Such cutting is performed using a surface grinding machine or the like. In addition, the maximum height Ry of the surface roughness after the cutting process can be appropriately controlled by selecting the size of the abrasive grains of the grindstone used in the cutting process, but if the grain size of the sintered body is enlarged, the maximum height Ry due to the peeling of the enlarged particles Gets bigger.

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. Low melting point solders such as indium can be used for the bonding material.

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 were dry-mixed with a high speed mixer manufactured by Astechnica, A mixed powder was prepared.

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 the refractive index of the material to be measured was 2.20. In addition, the same measurement conditions were used for the average particle diameter of the raw material powder described below. In addition, the average particle diameter of the raw material powder is the 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, the atomic ratio of metal elements contained in all raw powders is In/(In+Ga+Zn)=0.1, Ga/(In+Ga+Zn)=0.3, Zn/(In+ Each raw material powder was blended so that Ga+Zn)=0.6.

Next, to 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% by mass of water with respect to the mixed powder were added, followed by ball mill mixing. 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 10 hours, a temperature increase rate of 100°C/h, and a temperature decrease rate of 100°C/h.

Next, the obtained sintered body was cut to obtain a sputtering target having a width of 210 mm x a length of 710 mm x a thickness of 6 mm. In addition, grindstone #170 was used for such cutting.

[Examples 2 to 3]

Using the same method as in Example 1, a sputtering target was obtained. Further, in Examples 2 to 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 3]

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

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 the same as 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 can be measured by, for example, ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy: Inductively Coupled Plasma Emission Spectroscopy).

Subsequently, the relative density was measured for the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above. This relative density was measured based on the Archimedes method.

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

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 (10).

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

C ₁ : 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 (7.18g/cm3)

C ₂ : Mass% of 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 : Mass% of the ZnO powder used in the production of the oxide sintered body

·Ρ ₃ : Density of ZnO (5.60g/cm3)

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

Specifically, using Mitsubishi Chemical Corporation Loresta (registered trademark) HP MCP-T410 (serial 4 probe probe TYPE ESP), a probe was placed on the surface of the processed oxide sintered body, and the measurement was performed in AUTO RANGE mode. . The measurement locations were taken as a total of 5 locations near the center of the oxide sintered body and four corners, and the average value of each measurement was taken as the bulk resistance value of the sintered body.

Subsequently, about the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above, the section strength was measured, respectively. Such transverse strength was obtained by using a sample piece (total 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 is obtained according to JIS-R-1601 (bending strength test method of fine ceramics). It measured according to the measurement method of the three-point bending strength.

Here, for the above-described Examples 1 to 3 and Comparative Examples 1 to 3, the atomic ratio of each element contained in the mixed powder, the presence or absence of dry mixing during the production of the oxide sintered body, the firing temperature, the relative density of the oxide sintered body, Table 1 shows the measurement results of the specific resistance (bulk resistance) and the transverse strength.

It can be seen that the oxide sintered bodies of Examples 1 to 3 all have a relative density of 97.0% 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 40 mΩ·cm 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 40 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 with such a sputtering target, it is possible to suppress damage to the oxide sintered body.

Subsequently, while observing the surfaces of the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above using a scanning electron microscope (SEM), measurement of the average particle diameter of the crystals was performed. Done.

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

Thereafter, an etching solution at 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 It was immersed in 0:HNO ₃ =mixed at a ratio of 1:1:0.08) 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.). In addition, in the measurement of the average particle diameter, a BSE-COMP image having a magnification of 500 times and a range of 175 µm x 250 µm was randomly photographed at 10 fields to obtain an SEM image of the structure.

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

First, drawing was performed along the grain boundary, after all drawing was completed, image correction (Image→Adjust→Threshold) was performed, and noise remaining after image correction was removed (Process→Noise→Despeckle) as necessary.

After that, particle analysis was performed (Analyze→Analyze Particles), and the area in each particle was obtained, and then the diameter per area circle was calculated. The average value of the diameters per area circle of all particles calculated at 10 fields of view was taken as the average particle diameter in the present invention.

1 and 2 are SEM images of the oxide sintered body in Example 1. In addition, in Figs. 1 and 2, the portion shown in black is a chipping portion by surface polishing. As shown in Figs. 1 and 2, it can be seen that the oxide sintered body of Example 1 is composed of a single crystal phase.

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

Subsequently, the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above were each subjected to X-Ray Diffraction (XRD) measurement to obtain an 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: 30㎃

Scan speed: 5deg/min

Step: 0.02deg

Scan range: 2θ = 20 degrees to 70 degrees

4 is an X-ray diffraction chart of an oxide sintered body in Example 1. FIG. As shown in Fig. 4, in the X-ray diffraction chart of Example 1, diffraction peaks are observed in the following regions A to P in a range where the diffraction angle 2θ is 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, since the oxide sintered body of Example 1 is composed of a single-phase crystal phase, it can be seen that the diffraction peaks observed in the regions A to P are attributed to such a single-phase crystal phase. In other words, the single-phase crystal phase constituting the oxide sintered body of Example 1 can be identified by the chart obtained by this X-ray diffraction measurement.

5 is a diagram comparing the X-ray diffraction chart of the oxide sintered body in Example 1 with the peak positions in the X-ray diffraction chart of InGaZnO ₄ , In ₂ Ga ₂ ZnO ₇ and Ga ₂ ZnO ₄ .

As shown in Fig. 5, the single-phase crystal phase constituting the oxide sintered body of Example 1 has a diffraction peak at a peak position different from that of the known crystal phases (here, InGaZnO ₄ , In ₂ Ga ₂ ZnO ₇ and Ga ₂ ZnO ₄ ). It can be seen that is observed. Here, the "base crystal phase" means "a crystal phase in which the peak position of the X-ray diffraction chart is registered on 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 that has not been known so far.

Subsequently, for the sputtering targets of 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 was measured using a surface roughness measuring device (SJ-210 / manufactured by Mitsutoyo Co., Ltd.). Ten locations of the sputtering surface were measured, and the maximum value was taken as the maximum height Ry of the sputtering target. Table 2 shows the measurement results.

Subsequently, in Examples 1 to 3 and Comparative Examples 1 to 3 of the sputtering target obtained in the above was subjected to the color difference ΔE ^* and depth measure of the color difference ΔE ^* in the direction of the surface, respectively. In addition, "color difference ΔE ^* " is an index that quantifies the difference between two colors.

The maximum color difference ΔE ^* silver within such a surface is measured using a color difference meter (Konica Minolta Co., Ltd., color difference meter CP-300) at 50 mm intervals in the x-axis and y-axis directions, and measure the surface of the cut sputtering target. The L value, a value, and b value of each point were evaluated in the CIE1976 space. And from the difference ΔL, Δa, and Δb between the L value, a value, and b value of each of the measured points, the color difference ΔE ^* from the following equation (11) is obtained as a combination of all two points, and the obtained plurality of color differences ΔE ^* was the maximum value of the maximum color difference ΔE ^* in the surface.

In addition, the maximum color difference ΔE ^* in the depth direction is cut by 0.5 mm at an arbitrary point of the cut sputtering target, measured using a color difference meter at each depth up to the center of the sputtering target, and measured points L value, a value, and b value of were evaluated in the CIE1976 space. And, from the difference ΔL, Δa, and Δb of the L value, a value, and b value of each measured point, the color difference ΔE ^* is obtained as a combination of all two points, and the maximum value of the obtained color differences ΔE ^* is the maximum value in the depth direction. It was set as the color difference ΔE ^* .

Here, in order to evaluate the target from the amount of arcing (abnormal discharge) generated, the sputtering targets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were used as a bonding material using indium, which is a low melting point solder, and applied to a copper substrate. Joined.

Subsequently, 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 arcing (abnormal discharge) generated. Table 2 shows the evaluation results.

(Arking evaluation)

A: Very few.

B: There are many.

C: Very many.

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

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

In addition, it can be seen that all of the oxide sintered bodies of Examples 1 to 3 have an average particle diameter of 15.0 μm or less. Therefore, according to the embodiment, when such an oxide sintered body is subjected to grinding processing, it is possible to suppress the roughness of the surface by peeling large crystal grains from the surface.

In addition, it can be seen that all of the sputtering targets of Examples 1 to 3 have a maximum height Ry of 15.0 μm or less of the surface roughness of the oxide sintered body. Therefore, according to the embodiment, it is possible to suppress generation of nodules on the target surface during sputtering.

It can be seen that the sputtering targets of Examples 1 to 3 have a maximum color difference ΔE ^* of 10 or less in the in-plane direction and the depth direction. Therefore, according to the embodiment, since there is no variation in the crystal grain size or composition, it is suitable as a sputtering target.

As described above, embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and various modifications are possible 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 described, but the shape of the oxide sintered body is not limited to a plate shape, and may be any shape such as a cylinder.

Another effect or modification can be easily derived by a person skilled in the art. For this reason, the broader aspect of the present invention is not limited to the specific details and representative embodiments described while describing as described above. Accordingly, various modifications are possible without departing from the spirit or scope of the concept of the general invention defined by the appended claims and their equivalents.

Claims (11)

It is an oxide sintered body containing indium, gallium, and zinc in a ratio satisfying the following formulas (1) to (3),
It is composed of a single-phase crystal phase,
An oxide sintered body having an average particle diameter of the crystal phase of 15.0 μm or less.

The method of claim 1,
An oxide sintered body containing indium, gallium, and zinc in a ratio satisfying the following formulas (4) to (6).

The method according to claim 1 or 2,
An oxide sintered body containing indium, gallium, and zinc in a ratio satisfying the following formulas (7) to (9).

The method according to any one of claims 1 to 3,
The crystal phase is an oxide sintered body in which a diffraction peak is observed in the following regions A to P in a chart 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° The method according to any one of claims 1 to 4,
An oxide sintered body having a relative density of 97.0% or more. The method according to any one of claims 1 to 5,
Oxide sintered body having a breaking strength of 40 MPa or more. The method according to any one of claims 1 to 6,
Oxide sintered body with a resistivity of 40 mΩ·cm or less. A sputtering target comprising the oxide sintered body according to any one of claims 1 to 7. The method of claim 8,
A sputtering target with a maximum surface roughness Ry of 15.0 μm or less. The method of claim 8 or 9,
A sputtering target with a color difference ΔE ^* of 10 or less. A method for producing an oxide thin film, in which a film is formed by sputtering the sputtering target according to any one of claims 8 to 10.

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