JP6511209B1 - Oxide sinter, sputtering target and method for producing 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 a single phase crystal phase And the average grain size 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

  Embodiments of the disclosure relate to a sintered oxide body, a sputtering target, and a method of manufacturing an oxide thin film.

  Sputtering, which is a thin film forming method using a sputtering target, is extremely effective as a manufacturing method for forming a thin film with a large area and with high accuracy. Sputtering is widely used in display devices such as liquid crystal display devices. In the technical field of semiconductor layers such as thin film transistors (hereinafter referred to as “TFT”) in recent years, oxides represented by In—Ga—Zn complex oxide (hereinafter referred to as “IGZO”) instead of amorphous silicon. A semiconductor is attracting attention, and a sputtering method is also utilized for the formation of an IGZO thin film (see, for example, Patent Document 1).

  In such a sputtering method, problems such as abnormal quality of a thin film to be formed and generation of a crack of a sputtering target during sputtering may occur due to occurrence of abnormal discharge and the like. One way to avoid these problems is to increase the density of the sputtering target.

  Even if the target is dense, abnormal discharge may occur. For example, if the crystal phase constituting the target is a multiple phase, and there is a resistance difference between different crystal phases, there is a risk that an abnormal discharge will occur.

In the case of using an IGZO thin film as a semiconductor layer of a TFT, the semiconductor characteristics largely change depending on the ratio of In, Ga, and Zn, and various ratios have been studied. For example, in Patent Document 2, a ratio in which the ratio of each metal element is In <Ga <Zn is examined. The ratio of In, Ga, and Zn in the IGZO sputtering target can be appropriately adjusted so as to obtain predetermined semiconductor characteristics. 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 an IGZO sputtering target containing a large amount of Zn, a target consisting of a double phase consisting of a homologous crystal structure and a spinel structure of Ga ₂ ZnO ₄ has also been studied (see, for example, Patent Document 3).

However, the resistance of Ga ₂ ZnO ₄ is higher than that of the homologous crystal structure or the like, so there is a high risk of the occurrence of abnormal discharge. Therefore, the sputtering target is preferably a single phase having a homologous crystal structure.

  On the other hand, a high-density sputtering target composed of a single phase tends to have a larger crystal grain size than a sputtering target composed of a multiple phase. Then, when the crystal grain diameter is enlarged, the mechanical strength of the sputtering target may be reduced, and cracking may occur during sputtering.

  In addition, it is also important that the sputtering target has a uniform distribution of the above-mentioned characteristics in the sputtering plane. If the distribution such as density is not uniform in the plane, abnormal discharge may occur or cracking during sputtering may occur. In the case of an IGZO sputtering target, the nonuniformity of the characteristic distribution of the sputtering surface may appear as shading of the color difference.

JP 2007-73312 A JP, 2017-145510, A JP, 2008-163441, A

  One aspect of the embodiment is made in view of the above, and it is an object of the present invention to provide a sputtering target capable of stably performing sputtering and an oxide sintered body for manufacturing the sputtering target.

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 a single phase crystal phase. The average grain size of the crystalline 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, sputtering can be performed stably.

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

  Hereinafter, with reference to the accompanying drawings, embodiments of the oxide sintered body, the sputtering target and the method for producing an oxide thin film disclosed in the present application will be described. Note that 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 grain size of the crystal phase is 15.0 μm or less. Thereby, the bending strength of the oxide sintered body can be increased. Moreover, since it can suppress that the surface becomes rough due to the exfoliation of the enlarged particles on the surface when the oxide sintered body is ground, it is easy to obtain a smooth surface.

  The average particle diameter of the oxide sintered body of the embodiment is preferably 10.0 μm or less, more preferably 8.0 μm or less, and still more preferably 6.0 μm or less. More preferably, it is 0 μm or less. The lower limit value of the average particle diameter is not particularly limited, but is usually 1.0 μm or more.

  Further, since the 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.

Moreover, as for the oxide sinter of embodiment, the atomic ratio of each element satisfy | fills the following formula (1)-(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 use in a TFT can be obtained.

In the oxide sintered body of the embodiment, the atomic ratio of each element preferably satisfies 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)
It is more preferable that the atomic ratio of each element 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)

  Moreover, the oxide sinter of embodiment may contain the unavoidable impurity originating in a raw material etc. As unavoidable impurities in the oxide sintered body of the embodiment, Fe, Cr, Ni, Si, W, Cu, Al, etc. may be mentioned, and the content thereof is generally 100 ppm or less.

Moreover, in the chart obtained by X-ray diffraction measurement (CuKα ray), the diffraction peak is observed in the region of the following A to P in the crystal phase of the single phase constituting the oxide sintered body of the embodiment preferable.
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 ° -40.5 °
I. 43.0 ° -45.0 °
J. 46.5 ° to 48.5 °
K. 55.5 ° to 57.8 °
L. 57.8 ° to 59.5 °
M. 59.5 ° -61.5 °
N. 65.5 ° -68.0 °
O. 68.0 ° to 69.0 °
P. 69.0 ° to 70.0 °

  Thereby, when this oxide sinter is used for a sputtering target, it can suppress that abnormal discharge occurs. Therefore, according to the embodiment, generation of particles due to such abnormal discharge can be suppressed, so that the production yield of the TFT can be improved.

  The oxide sintered body of the embodiment preferably has a relative density of 97.0% or more. Thereby, when this oxide sinter is used as a sputtering target, the discharge state of DC sputtering can be stabilized. In addition, as for the oxide sinter of embodiment, it is more preferable that relative density is 98.0% or more, and it is still more preferable that relative density is 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 uptake of gas components in the atmosphere can be easily prevented. In addition, during the sputtering, abnormal discharge starting from the void, cracking of the sputtering target, and the like are less likely to occur.

  Moreover, it is preferable that the oxide sintered compact of embodiment is 40 Mpa or more in bending strength. Thereby, when manufacturing a sputtering target using this oxide sinter, when performing sputtering by this sputtering target, it can suppress that an oxide sinter is damaged.

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

  Moreover, as for the oxide sinter used for the sputtering target of embodiment, it is preferable that largest height Ry of surface roughness is 15.0 micrometers or less. As a result, when sputtering is performed using such a sputtering target, generation of nodules on the surface of the target can be suppressed.

  In addition, as for the oxide sinter used for the sputtering target of embodiment, it is more preferable that largest height Ry is 11.0 micrometers or less, and it is further more preferable that it is 10.0 micrometers or less. The lower limit of the maximum height Ry is not particularly limited, but is usually 0.1 μm or more.

  The oxide sintered body of the embodiment preferably has a specific resistance of 40 mΩ · cm or less. Thus, when such an oxide sintered body is used as a sputtering target, sputtering using an inexpensive DC power supply becomes possible, and the film forming rate can be improved. Moreover, thereby, generation | occurrence | production of abnormal discharge can be suppressed.

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

In the sputtering target of the embodiment, the color difference ΔE ^* of the sputtering target surface is preferably 10 or less. Further, the color difference in the depth direction of the sputtering target is also preferably ΔE ^* of 10 or less. When this numerical value satisfies the above condition, there is no bias in the crystal grain size or the composition, which is suitable as a sputtering target.

Incidentally, the sputtering target of the embodiment, more preferably the color difference of the entire surface and depth Delta] E ^* is 9 or less, and further preferably the color difference Delta] E ^* is 8 or less.

<Each manufacturing process of oxide sputtering target>
The oxide sputtering target of the embodiment can be produced, for example, by the following method. First, the raw material powder is mixed. The raw material powders are 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 component ratio in the oxide sintered body.

  It is preferable to dry-mix each raw material powder in advance. There is no restriction | limiting in particular in the method of this dry mixing, It can mix using various mixers, such as a container rotation type mixer and a container fixed type mixer. Above all, it is preferable to mix using, for example, a high speed mixer made by Earth Technica Co., Ltd., because high speed dispersion and mixing can be performed by applying shear force and impact force to the raw material powder. When the raw material powder is uniformly dispersed and mixed by performing the dry mixing treatment in advance in this manner, a sintered body having a single phase structure is easily obtained, and the color difference is preferably in the range described above.

  As a method of producing a molded object from the mixed powder mixed in this manner, for example, a slip casting method, CIP (Cold Isostatic Pressing: cold isostatic pressing method) and the like can be mentioned. Subsequently, two types of methods will be described as specific examples of the molding method.

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

  Further, the dispersion medium used when preparing the slurry is not particularly limited, and can be appropriately selected from water, alcohol and the like according to the purpose. Moreover, there is no restriction | limiting in particular also in the method of preparing a slurry, For example, the ball mill mixing which puts and mixes a mixed powder, an organic additive, and a dispersion medium in a pot can be used. The slurry thus obtained is poured into a mold, and the dispersion medium is removed to prepare a compact. The molds that can be used here are metal molds, plaster molds, resin molds that perform dispersion medium removal 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 for pressure forming. I do. Organic additives which can be used here are known binders, dispersants and the like.

  Further, the dispersion medium used when preparing the slurry is not particularly limited, and can be appropriately selected from water, alcohol and the like according to the purpose. Further, the method of 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 put in a pot and mixed can be used.

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

  Next, the obtained molded body is fired to prepare a sintered body. There is no restriction | limiting in particular in the baking furnace which produces this sintered body, The baking furnace which can be used for manufacture of a ceramic sintered compact 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. It is preferable to control below the said temperature from a viewpoint of suppressing the enlargement of the structure | tissue of a sintered compact and preventing a crack, while the sintered compact of a high density is obtained, so that a calcination temperature is high. Moreover, since it becomes difficult to form a single phase crystalline phase as a calcination temperature is less than 1350 degreeC, it is unpreferable.

  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 cutting can be appropriately controlled by selecting the size of the abrasive grains of the grinding stone used for cutting, but the particle diameter of the sintered body is enlarged. Then, the maximum height Ry is increased by the exfoliation of the enlarged particles.

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

Example 1
Earth Technica Co., Ltd .: In ₂ O ₃ powder having an average particle diameter of 0.6 μm, Ga ₂ O ₃ powder having an average particle diameter of 1.5 μm, and ZnO powder having an average particle diameter of 0.8 μm Dry mixing was carried out using a high speed mixer to prepare a mixed powder.

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

  In addition, in preparation of this mixed powder, the atomic ratio of the metal element contained in all the raw material powder is In / (In + Ga + Zn) = 0.1, Ga / (In + Ga + Zn) = 0.3, Zn / (In + Ga + Zn) = Each raw material powder was mix | blended so that it might be set to 0.6.

  Next, in the pot in which the mixed powder is prepared, 0.2% by mass of the binder to the mixed powder, 0.6% by mass of the dispersing agent to the mixed powder, and 20% by mass to the mixed powder Water was added and mixed with 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 molded body. Next, this molded body was fired to produce a sintered body. The baking was performed at a baking temperature of 1500 ° C., a baking time of 10 hours, a temperature rising rate of 100 ° C./h, and a temperature falling rate of 100 ° C./h.

  Next, the obtained sintered body was cut to obtain a sputtering target of 210 mm wide × 710 mm long × 6 mm thick. The # 170 whetstone was used for such cutting.

[Examples 2 to 3]
A sputtering target was obtained using the same method as in Example 1. In Examples 2 to 3, the raw material powders were blended such that the atomic ratio of the metal elements contained in all the raw material powders was the atomic ratio described in Table 1 when preparing the mixed powder.

Comparative Examples 1 to 3
In Comparative Examples 1 to 3, in preparation of the mixed powder, the atomic ratio of metal elements contained in all the raw material 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. The firing temperature was set to the temperature shown in Table 1, and in Comparative Example 2, dry mixing was not performed. A sputtering target was obtained using the same method as Example 1 except for the above.

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

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

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

Moreover, this theoretical density g (g / cm ³ ) was calculated from the mass% and the density of the raw material powder used for producing the oxide sintered body. Specifically, it was calculated by the following equation (10).
_{ρ = {(C 1/100} ) / ρ 1 + (C 2/100) / ρ 2 + (C 3/100) / ρ 3} -1 ·· (10)

Incidentally, _C 1 -C ₃ and ρ ₁ ~ρ ₃ in the above formulas, respectively show the following values.
C ₁ :% by mass of In ₂ O ₃ powder used for producing the oxide sintered body
· Ρ ₁ : density of In ₂ O ₃ (7.18 g / cm ³ )
C ₂ :% by mass of Ga ₂ O ₃ powder used for producing the oxide sintered body
· Ρ ₂ : density of Ga ₂ O ₃ (5.95 g / cm ³ )
C ₃ :% by mass of ZnO powder used for producing the oxide sintered body
· _{3 3} : density of ZnO (5.60 g / cm ³ )

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

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

  Subsequently, the bending strength of each of the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above was measured. This bending strength uses the bending strength of JIS-R-1601 (fine ceramics) using the sample piece (total length 36 mm or more, width 4.0 mm, thickness 3.0 mm) cut out from oxide sinter by wire electric discharge machining. It measured according to the measuring method of three-point bending strength of test method).

  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 at the time of producing the oxide sintered body, the firing temperature, and the oxide The measurement results of relative density, specific resistance (bulk resistance) and bending strength of the sintered body are shown in Table 1.

  The oxide sintered bodies of Examples 1 to 3 are all found to 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.

  Moreover, it turns out that the oxide sintered compacts of Examples 1 to 3 all have a specific resistance of 40 mΩcm 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 forming rate can be improved.

  Moreover, it turns out that the oxide sintered compacts of Examples 1 to 3 all have a bending strength of 40 MPa or more. Therefore, according to the embodiment, when the sputtering target is manufactured using such an oxide sintered body, or when sputtering is performed using the sputtering target, the oxide sintered body can be prevented from being damaged. .

  Subsequently, the surfaces of the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained as described above are observed using a scanning electron microscope (SEM: Scanning Electron Microscope), and the average particle diameter of crystals is obtained. The measurement of

  Specifically, the cut surface obtained by cutting the oxide sintered body is polished stepwise using emery paper # 180, # 400, # 800, # 1000, # 2000 and finally buffing I finished the mirror surface.

  After that, the etching solution at 40 ° C. (nitric acid (60 to 61% aqueous solution, made by Kanto Chemical Co., Ltd.), hydrochloric acid (35.0 to 37.0% aqueous solution, made by Kanto Chemical Co., Ltd.) and pure water in volume ratio Etching was performed by immersion for 2 minutes in HCl: H2O: HNO3 = 1: 1: 0.08).

  Then, the appeared surface was observed using a scanning electron microscope (SU3500, manufactured by Hitachi High-Technologies Corporation). In the measurement of the average particle diameter, BSE-COMP images at magnifications of 500 and 175 μm × 250 μm were randomly taken in 10 fields of view, and SEM images of the tissue were obtained.

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

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

  Thereafter, particle analysis was performed (Analyze → Analyze Particles) to obtain the area of each particle, and then the area equivalent circle diameter was calculated. The average value of the area equivalent circular diameter of all the particles calculated in 10 visual fields 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. FIG. In FIG. 1 and FIG. 2, the black-appearing part is a chipped part 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-phase crystal phase.

  FIG. 3 is a SEM image of the oxide sintered body in Comparative Example 2. Note that, in FIG. 3, a portion that appears black is a phase in which indium is reduced (In poor phase). As shown in FIG. 3, it can be seen that the oxide sintered body of Comparative Example 2 is composed of a multiple phase crystal phase.

  Subsequently, X-Ray Diffraction (XRD) measurement is performed on each of the oxide sintered bodies of Examples 1 to 3 and Comparative Examples 1 to 3 obtained above, to obtain X-ray diffraction charts. The

In addition, the concrete measurement conditions of this X-ray-diffraction measurement were as follows.
-Device: SmartLab (manufactured by Rigaku Corporation, registered trademark)
・ Source: CuKα ray ・ Tube voltage: 40kV
・ Tube current: 30 mA
・ Scan speed: 5deg / min
・ Step: 0.02 deg
・ Scan range: 2θ = 20 degrees to 70 degrees

FIG. 4 is an X-ray diffraction chart of the oxide sintered body in Example 1. 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 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 ° -40.5 °
I. 43.0 ° -45.0 °
J. 46.5 ° to 48.5 °
K. 55.5 ° to 57.8 °
L. 57.8 ° to 59.5 °
M. 59.5 ° -61.5 °
N. 65.5 ° -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, the diffraction peaks observed in the above A to P regions are the single-phase crystal phase. It turns out that it is due to. In other words, the chart obtained by this X-ray diffraction measurement makes it possible to identify the single-phase crystal phase constituting the oxide sintered body of Example 1.

FIG. 5 is a diagram comparing peak positions in the X-ray diffraction chart of the oxide sintered body in Example 1 with 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 is a known crystal phase (here, InGaZnO ₄ , In ₂ Ga ₂ ZnO ₇ and Ga ₂ ZnO ₄ ) It can be seen that diffraction peaks are observed at different peak positions. Here, “known crystal phase” means “a crystal phase in which a peak position of an X-ray diffraction chart is registered in a Joint Committee of Powder Diffraction Standards (JCPDS) card”.

  That is, it is understood that the single phase crystal phase constituting the oxide sintered body of Example 1 is a crystal phase which has not been known so far.

  Subsequently, the maximum height Ry of the surface roughness was measured for each of the sputtering targets of Examples 1 to 3 and Comparative Examples 1 to 3 obtained as described above. Specifically, the maximum height Ry of the sputtering surface was measured using a surface roughness measuring device (SJ-210 / manufactured by Mitutoyo Co., Ltd.). Ten points on the sputtering surface were measured, and the maximum value was taken as the maximum height Ry of the sputtering target. The measurement results are shown in Table 2.

Subsequently, the sputtering target of Examples 1 to 3 and Comparative Examples 1 to 3 obtained in the above, the measurement of the color difference Delta] E ^* color difference Delta] E ^* and the depth direction of the surface was carried out, respectively. The “color difference ΔE ^* ” is an index that digitizes the difference between the two colors.

The maximum color difference ΔE ^* in the surface is measured by measuring the surface of the cut sputtering target at intervals of 50 mm in the x-axis and y-axis directions using a color difference meter (color difference meter CP-300 manufactured by Komi Minolta Co., Ltd.) The L, a and b values of each point evaluated were evaluated in the CIE 1976 space. Then, the color difference ΔE ^* is determined from the combination of all the two points from the following equation (11) from the L value of each of the measured points, the difference between the a value and the b value, ΔL, Δa, Δb. The maximum value of the plurality of color differences ΔE ^* is taken 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 cut by 0.5 mm at any position of the cut sputtering target, and measured using a color difference meter at each depth to the central portion of the sputtering target, The L value, a value and b value of each point measured were evaluated in the CIE 1976 space. Then, a color difference ΔE ^* is obtained from the L value of each of the measured points, the difference between the a value and the b value ΔL, Δa, Δb from the combination of all two points, and a plurality of color differences ΔE ^{* obtained} The maximum value is taken as the maximum color difference ΔE ^* in the depth direction.

  Here, in order to evaluate the target from the generation amount of arcing (abnormal discharge), using the sputtering target obtained in Examples 1 to 3 and Comparative Examples 1 to 3 as a bonding material, indium which is a low melting point solder, Bonded to a copper base.

Then, sputtering was performed using the sputtering target of Examples 1-3 and Comparative Examples 1-3, and evaluation of the target was performed from the generation amount of arcing (abnormal discharge). The evaluation results are shown in Table 2.
(Arking evaluation)
A: Very little.
B: 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, surface roughness maximum height Ry of the maximum color difference Delta] E * in the in-plane ^direction, the maximum color difference Delta] E * in the depth ^direction, and the measurement results of the arcing evaluation are shown in Table 2.

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

  Moreover, it turns out that the oxide sinter of Examples 1-3 is 15.0 micrometers or less in average particle diameter altogether. Therefore, according to the embodiment, when the oxide sintered body is ground, large crystal grains are peeled off from the surface, so that the surface can be prevented from becoming rough.

  Moreover, it turns out that the sputtering targets of Examples 1 to 3 all have the maximum height Ry of the surface roughness of the oxide sintered body of 15.0 μm or less. Therefore, according to the embodiment, generation of nodules on the target surface can be suppressed when sputtering.

It is understood 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 bias in the crystal grain size or the composition, it is suitable as a sputtering target.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, A various change is possible unless it deviates from the meaning. For example, although the embodiment shows an example in which a sputtering target is manufactured using a plate-like oxide sintered body, the shape of the oxide sintered body is not limited to a plate-like shape, and any shape such as a cylindrical shape It may be shaped.

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

Claims (10)

An oxide sintered body containing indium, gallium and zinc in a ratio satisfying the following formulas (4) to (6) ,
Composed of single phase crystal phase,
The oxide sinter whose average particle diameter of the said crystal phase is 15.0 micrometers or less.
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 according to claim 1, containing indium, gallium and zinc in 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 claim 1 or 2 , wherein a diffraction peak is observed in a region of the following A to P in the chart obtained by X-ray diffraction measurement (CuKα ray) in the crystal phase.
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 ° -40.5 °
I. 43.0 ° -45.0 °
J. 46.5 ° to 48.5 °
K. 55.5 ° to 57.8 °
L. 57.8 ° to 59.5 °
M. 59.5 ° -61.5 °
N. 65.5 ° -68.0 °
O. 68.0 ° to 69.0 °
P. 69.0 ° to 70.0 ° The oxide sintered body according to any one of claims 1 to 3 , which has a relative density of 97.0% or more. The oxide sintered body according to any one of claims 1 to 4 , which has a bending strength of 40 MPa or more. The oxide sintered body according to any one of claims 1 to 5 , which has a specific resistance of 40 mΩcm or less. A sputtering target comprising the oxide sintered body according to any one of claims 1 to 6 . The sputtering target according to claim 7 , wherein the maximum height Ry of the surface roughness is 15.0 μm or less. The sputtering target according to claim 7 or 8 color difference Delta] E ^* is 10 or less. Deposited by sputtering a sputtering target according to any one of claims 7-9, method of manufacturing an oxide thin film.