WO2010018707A1

WO2010018707A1 - Gallium oxide-tin oxide based oxide sintered body and oxide film

Info

Publication number: WO2010018707A1
Application number: PCT/JP2009/060430
Authority: WO
Inventors: 太宇都野; 一吉井上; 健治後藤
Original assignee: 出光興産株式会社
Priority date: 2008-08-11
Filing date: 2009-06-08
Publication date: 2010-02-18
Also published as: TW201006781A; JPWO2010018707A1

Abstract

Disclosed is an oxide sintered body characterized by containing one or more gallium stannate compound phases selected from Ga₄SnO₈, Ga₄Sn₅O₁₆ and Ga₃Sn₄O₁₂, and a tin oxide phase. The oxide sintered body is also characterized in that at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum and antimony is dispersed therein.

Description

Gallium oxide-tin oxide based oxide sintered body and oxide film

The present invention relates to a gallium oxide-tin oxide based oxide sintered body, a method for producing the same, and an oxide film. In particular, the present invention relates to a tin oxide-based transparent amorphous thin film material such as a display panel or a touch panel.

The transparent conductive film has both high visible light transmittance and high conductivity, such as a liquid crystal display element, a transparent electrode of a display element such as a plasma light emitting element, a transparent electrode of a solar cell, a heat ray reflective film of automobile or architectural glass, a CRT Widely used as a transparent heating element for various types of anti-fogging, such as antistatic films or frozen and refrigerated showcases.

Conventionally, as a transparent conductive film, an ITO (tin-doped indium oxide) film is mainly used because a low resistance film can be easily obtained. In particular, ITO films are widely used as display element electrodes. In addition, a low-cost zinc oxide-based transparent conductive film and a low-cost, highly chemical-resistant tin oxide-based transparent conductive film are also known.

As a problem of the conventional transparent conductive film material, ITO is an obstacle to cost reduction because indium which is the main component is expensive. About a zinc oxide type transparent conductive film, the chemical resistance with respect to an acid, an alkali, etc. is low. Therefore, it is difficult to apply the zinc oxide-based transparent conductive film to industrial products such as display elements.

The tin oxide-based transparent conductive film is extremely excellent in chemical resistance as compared with the ITO film and the zinc oxide-based transparent conductive film. The tin oxide system is produced by a spray method or a CVD method as an industrial production method, but it is difficult to form a uniform film thickness. In addition, chlorine, hydrogen chloride, etc. are generated during film formation, and there is a problem of environmental pollution due to these exhaust gases (or effluents), and there is a need to establish a film formation method by sputtering that does not generate chlorine or hydrogen chloride. . As a large-area film forming method, a sputtering method which is easy to obtain a uniform thin film and has little environmental pollution is suitable.

Regarding transparent conductive oxide, for example, Patent Document 1 proposes a transparent conductive oxide composed of one or more selected from the group consisting of In ₂ O ₃ , ZnO, SnO ₂ , and Ga ₂ O _3. Has been. However, there is no specific description or suggestion of an oxide sintered body containing tin oxide as a main component.
Patent Documents 2 and 3 propose ITO films containing gallium. This film needs to contain expensive indium oxide as a main component.

In Patent Document 4, SnO ₂ based sintered body obtained by adding the _Ga 2 _{O 3} to SnO ₂ is disclosed. However, there is no specific method or suggestion for producing a practical gallium oxide-tin oxide based oxide sintered body, such as adjusting the bulk resistance and avoiding cracking of the target during sputtering.
Patent Document 5 describes an amorphous SnO ₂ transparent conductive film. However, this film contains expensive In ₂ O ₃ as an essential component.

In addition, in the SnO ₂ based sintered body, there is a case where first antimony oxide (Sb ₂ O ₃ ) is added to lower the resistance value of the SnO ₂ thin film. In order to produce a sputtering target made of a SnO ₂ sintered body to which Sb ₂ O ₃ is added, a hot press (HP) method is generally used. In the hot press method, sintering is performed while pressure is applied, which is advantageous in improving density and strength to some extent. However, it is not easy to obtain a large sintered body due to limitations on the apparatus.
Therefore, conventionally, when producing a large-sized sputtering target, a target is comprised by bonding together a plurality of sintered bodies. However, when a SnO ₂ thin film is formed by sputtering using a target having a plurality of seams, there is a problem that arcing and nodules are generated from the seams and stable film formation cannot be performed. For this reason, a seamless target or a target with few seams is required, and a technique for manufacturing a larger sintered body is required.

As a method for producing a large sintered body, a cold press (CP) method in which a molded body obtained by press-molding the raw material mixed powder is sintered, or a molded body obtained by casting the raw material mixed powder is sintered. There is a casting method to tie.

However, when producing a SnO ₂ target to which Sb ₂ O ₃ is added, Sb ₂ O ₃ is generally used at a temperature of about 1000 ° C., such as in the air, in an oxygen atmosphere, in an inert gas, or in a vacuum. In order to melt in atmospheric conditions, it is necessary to heat-treat at a temperature of at least 1000 ° C. Therefore, when the sintered body is fired by the CP method or the casting method, since the sintering temperature is limited, the sintering does not proceed sufficiently and only a brittle sintered body with insufficient sintering can be obtained. There is a problem. When a sputtering target is produced from such a brittle sintered body, the sintered body is cracked or cracked by processing stress during the processing, or cracked by thermal stress when bonding the sintered body to the backing plate. There is a problem that occurs. The tendency for such cracks to occur becomes more prominent as the size of the target increases.

An object of the present invention is to provide an oxide sintered body that does not contain In, which is a noble metal element, or does not have a main component, and has a low bulk resistance and is unlikely to be cracked or cracked.
Another object of the present invention is to provide a tin oxide film having a high light transmittance and a method for producing the same.

JP-A-7-33030 JP-A-4-272612 JP 2000-129432 A Patent No. 3957917 Japanese Patent No. 3806521

According to the present invention, the following oxide sintered bodies and the like are provided.
1. Ga ₄ containing _{_{_{_{SnO 8, Ga 4 Sn 5 O}}}} 16 and _Ga 3 _Sn 4 _{O 12} and one or more stannate gallium compound phase selected from a tin oxide phase,
An oxide sintered body in which at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum, and antimony is dispersed.
2. 2. The oxide sintered body according to 1, wherein the ratio [Ga / (Ga + Sn)] of the gallium element to the total of the gallium element and tin element is 0.01 to 0.80 in atomic ratio.
3. 3. The oxide sintered body according to 1 or 2, wherein at least one element selected from niobium, tantalum and antimony is dispersed.
4). 3. The tin oxide phase according to 1 or 2, wherein at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum, and antimony is solid solution substituted. Oxide sintered body.
5). 5. The oxide sintered body according to 4, wherein the amount of the element subjected to solid solution substitution is 0.08 or less in atomic ratio with respect to the total amount of all metal elements.
6). The oxide sintered body according to any one of 1 to 5, wherein an average particle diameter of the tin oxide phase or the gallium stannate compound phase is 5 μm or less.
7). Mixing a gallium compound and a tin compound;
Molding the mixture obtained in the above step to obtain a molded product;
The method for producing an oxide sintered body according to any one of 1 to 6, comprising a step of sintering the molded product obtained in the step at 1200 to 1550 ° C.
8). 8. The method for producing an oxide sintered body according to 7, wherein, in the sintering step, the sintering temperature is set at a heating rate of 0.5 ° C./min or more.
9. An oxide film obtained by forming a film by a sputtering method or an ion plating method using a target comprising the oxide sintered body according to any one of 1 to 7.
10. 10. The oxide film according to 9, formed by a sputtering method.

According to the present invention, it is an oxide sintered body that does not contain an In element or does not contain a main component, has a low bulk resistance, becomes noduleless during sputtering, can suppress abnormal discharge, An oxide sintered body that is less prone to cracking can be provided.
Further, a tin oxide film having a high light transmittance and a method for producing the same can be provided.

2 is an X-ray diffraction chart of an oxide sintered body produced in Example 1. FIG. 3 is an X-ray diffraction chart of an oxide sintered body produced in Example 2. FIG. 4 is an X-ray diffraction chart of an oxide sintered body produced in Example 3. FIG. 6 is an X-ray diffraction chart of an oxide sintered body produced in Example 4. 6 is an X-ray diffraction chart of an oxide sintered body produced in Example 5. FIG. 6 is an X-ray diffraction chart of an oxide sintered body produced in Example 6. FIG. 7 is an X-ray diffraction chart of an oxide sintered body produced in Example 7. FIG. 10 is an X-ray diffraction chart of an oxide sintered body produced in Comparative Example 6. 10 is an X-ray diffraction chart of an oxide sintered body produced in Comparative Example 7.

The oxide sintered body of the present invention contains one or more gallium stannate compound phases selected from Ga ₄ SnO ₈ , Ga ₄ Sn ₅ O ₁₆ and Ga ₃ Sn ₄ O ₁₂ and a tin oxide phase. . In addition, at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum, and antimony is dispersed.
It contains one or two or more gallium stannate compound phases selected from Ga ₄ SnO ₈ , Ga ₄ Sn ₅ O ₁₆ and Ga ₃ Sn ₄ O ₁₂ . The presence of the gallium stannate compound phase in the oxide sintered body enables stable sputtering.
Among the gallium stannate compound phases described above, in particular, having a Ga ₄ SnO ₈ phase increases the dispersibility of gallium and suppresses abnormal discharge, thereby enabling stable sputtering. Moreover, since Ga ₄ SnO ₈ is doped with Sn element, the resistance of the Ga ₄ SnO ₈ phase is lowered, so that the bulk resistance of the sintered body is reduced.
Moreover, there exists an effect which raises sinterability by containing Ga element. Specifically, a Ga ₄ SnO ₈ phase is precipitated in the sintered body during sintering, and the density of the sintered body increases.
The oxide sintered body of the present invention contains a tin oxide phase. By adding the above element such as zinc to the tin oxide phase, the strength of the sintered body can be increased or the bulk resistance can be reduced.

The presence of a gallium stannate compound phase and a tin oxide phase in the sintered body can be determined by X-ray diffraction. The measured diffraction spectrum is confirmed by having a JCPDS (Joint Committee on Powder Diffraction Standards) peak pattern of the hexagonal layered compound phase and indium oxide phase, or a similar (shifted) pattern thereof.

In the oxide sintered body of the present invention, the ratio [Ga / (Ga + Sn)] of the gallium element to the total of the gallium element and tin element is preferably 0.01 to 0.80 in atomic ratio. Within this range, a Ga ₄ SnO ₈ phase can be obtained without the Ga ₂ O ₃ phase being precipitated during the production of the oxide sintered body (during sintering). Thereby, the bulk resistance of a sintered compact becomes low, and when it uses as a sputtering target, stable sputtering can be performed.
Further, if Ga / (Ga + Sn) is in the range of 0.01 to 0.80, the specific resistance of the manufactured thin film is 0.1 to 100 Ωcm depending on the conditions for manufacturing the thin film, which is suitable for semiconductor applications. .
The ratio of the gallium element is more preferably 0.05 to 0.70, and particularly preferably 0.20 to 0.60.
Note that the content (atomic ratio) in the oxide sintered body can be obtained by measuring the abundance of each element by ICP (Inductively Coupled Plasma) measurement.

When the produced thin film is used for semiconductor applications, Ga / (Ga + Sn) is preferably 0.25 to 0.80, and particularly preferably 0.3 to 0.50.

On the other hand, when the thin film is used as a transparent conductive film, Ga / (Ga + Sn) is preferably in the range of 0.01 to 0.25. Within this range, the specific resistance of the thin film is 0.0001 to 0.1 Ωcm depending on the conditions for producing the thin film, which is suitable for a transparent electrode or the like. When used as a transparent conductive film, Ga / (Ga + Sn) of 0.05 to 0.25 is more preferable because the transparency is improved. In particular, Ga / (Ga + Sn) is preferably 0.10 to 0.20.

The oxide sintered body of the present invention contains at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum and antimony in a dispersed state.
In particular, it is preferable that the above element is substituted in the tin oxide phase of the oxide sintered body. Thereby, since the density of a sintered compact improves, the intensity | strength of a sintered compact becomes high. Therefore, cracks can be prevented when the sintered body is used as a sputtering target.

Whether the above-mentioned elements are dispersed in the oxide sintered body can be confirmed by surface analysis using an electron beam microanalyzer (EPMA). In the oxide sintered body, the elements need not be aggregated at one place but should be distributed in a plurality of regions. It is preferable that the above elements are uniformly dispersed in the tin oxide phase of the oxide sintered body.

Among the above-mentioned elements, each element of zinc, silicon, aluminum, indium, germanium, and titanium is derived from a sintering aid (such as oxide powder of these elements) used during the production of the sintered body. By using the sintering aid, the density of the sintered body can be improved. Here, the sintering aid has an effect of promoting the sintering reaction by promoting the firing reaction or generating a liquid phase. As the sintering aid, a compound of zinc, silicon, indium or aluminum is preferable, and zinc or indium is particularly preferable.

Further, each element of niobium, tantalum, tungsten, molybdenum, or antimony is dispersed in the oxide sintered body of the present invention, or by solid solution substitution with Sn in the gallium stannate compound phase and / or tin oxide phase. , There is an effect of increasing the carrier concentration and lowering the bulk resistance of the oxide sintered body. Niobium, tantalum or antimony is particularly preferable.
In addition, each element of zinc and indium has an effect of reducing the resistivity of a thin film manufactured when an oxide sintered body is used as a sputtering target.
In addition, when an oxide sintered body containing each element of aluminum, silicon, germanium, or titanium is used as a sputtering target, there is an effect of lowering the carrier concentration of the produced thin film. When the thin film is used as a semiconductor layer, It is particularly effective.
Furthermore, by containing niobium, sublimation of tin oxide can be suppressed, so that the sintering temperature can be raised.

The content of the additive element is preferably 0.08 or less in terms of an atomic ratio with respect to the total amount of all metal elements in the sintered body. If it exceeds 0.08, the bulk resistance of the sintered body may increase, or the thin film produced using the sintered body may be colored. The content of the additive element is more preferably 0.01 to 0.08, and particularly preferably 0.02 to 0.05.

In the sintered body of the present invention, the average particle diameter of the tin oxide phase or the gallium stannate compound phase is preferably 5 μm or less. If the average particle size is 5 μm or less, abnormal discharge such as arc discharge does not occur during sputtering, and generation of black protrusions called nodules on the target can be suppressed. As a result, a film free from massive foreign matters is obtained on the thin film to be formed. If there are massive foreign substances in the thin film, etching may not be performed properly or a desired pattern may not be formed. Moreover, the upper and lower wiring metals may be short-circuited by foreign substances.
In addition, an average particle diameter is the value measured by the surface analysis of the electron beam microanalyzer (EPMA). Specifically, the surface analysis of oxygen and metal in a 50 × 50 micron visual field was performed, the major axis of each phase grain was calculated, and the average value of the particle diameters in the visual field was taken as the average grain size.

The relative density [(actual density) / (theoretical density)] of the sintered body of the present invention is preferably 85% or more, and more preferably 90% or more. A relative density of 85% or more is preferred because the bulk resistance of the obtained sputtering target does not become too high, and abnormal discharge such as arc discharge does not occur during sputtering. Furthermore, if the relative density is 90% or more, it is preferable because cracks and cracks are hardly generated in the sintered body, and a large-sized sintered body can be produced. In the present invention, the relative density can be increased by increasing the Ga concentration.

The bulk resistance of the sintered body of the present invention is preferably less than 100 kΩcm. More preferably, it is 5 kΩcm or less, and further preferably 1 kΩcm or less.
The sintered body of the present invention is preferably amorphous. Amorphous materials are preferred because they have high scratch resistance and no fine irregularities on the surface of the sintered body.

The sintered body of the present invention is obtained by the production method of the present invention described below.
The method for producing an oxide sintered body of the present invention includes the following steps (A) to (C).
(A) The process of mixing the raw material containing a gallium compound and a tin compound at least (B) The process of shape | molding the mixture obtained at a process (A) (C) The process of sintering the obtained molded object

(A) Mixing step In this step, the gallium compound powder and the tin compound powder, which are raw material powders, are mixed.
The gallium compound and tin compound may be oxides or oxides (oxide precursors) that become oxides after firing. Examples of the gallium oxide precursor and tin oxide precursor include gallium or tin sulfide, sulfate, nitrate, halide (chloride, bromide, etc.), carbonate, organic acid salt (acetate, propionate). , Naphthenate, etc.), alkoxide (methoxide, ethoxide, etc.), organometallic complex (acetylacetonate, etc.) and the like.
Among these, nitrates, organic acid salts, alkoxides, or organometallic complexes are preferred in order to completely thermally decompose at low temperatures so that no impurities remain. It is optimal to use an oxide of each metal.

In addition to gallium compound powder and tin compound powder, a compound (oxide) containing at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum and antimony Etc.) may be added. These compounds function as, for example, a sintering aid.

The purity of each raw material is usually 99.9% by mass (3N) or more, preferably 99.99% by mass (4N) or more, more preferably 99.995% by mass or more, particularly preferably 99.999% by mass (5N ) That's it. If the purity of each raw material is 99.9% by mass (3N) or more, the semiconductor characteristics are not deteriorated by impurities such as Fe, Ni, Cu, and the reliability can be sufficiently maintained. In particular, it is preferable that the content of Na, K, and Ca is less than 100 ppm because reliability is improved when a thin film transistor is manufactured.

The mixing is preferably carried out by (i) solution method (coprecipitation method) or (ii) physical mixing method. More preferably, a physical mixing method is used for cost reduction.
In the physical mixing method, the raw material powder containing the gallium compound and the tin compound is put into a mixer such as a ball mill, a jet mill, a pearl mill, or a bead mill and mixed uniformly.
The mixing time is preferably 1 to 200 hours. If it is less than 1 hour, the elements to be dispersed may be insufficiently homogenized, and if it exceeds 200 hours, it may take too much time and productivity may be deteriorated. A particularly preferred mixing time is 10 to 60 hours.

As a result of mixing, the obtained raw material mixed powder preferably has an average particle size of 0.01 to 1.0 μm. When the particle diameter is less than 0.01 μm, the powder is likely to aggregate, handling is poor, and a dense sintered body may not be obtained. On the other hand, if it exceeds 1.0 μm, a dense sintered body may not be obtained.

In this invention, after mixing raw material powder, you may include the process of calcining the obtained mixture.
In the calcining step, the mixture obtained in the above step is calcined. By performing calcination, it becomes easy to increase the density of the finally obtained sputtering target.
In the calcination step, it is preferable to heat-treat the mixture obtained in step (a) at 200 to 1000 ° C. for 1 to 100 hours, preferably 2 to 50 hours. A heat treatment condition of 200 ° C. or higher and 1 hour or longer is preferable because the raw material compound is sufficiently thermally decomposed. If the heat treatment conditions are 1000 ° C. or less and 100 hours or less, the particles are not coarsened, which is preferable.
Furthermore, it is preferable to grind | pulverize the mixture after calcining obtained here before the shaping | molding process and sintering process which follow. The mixture after calcination is suitably pulverized using a ball mill, roll mill, pearl mill, jet mill or the like. The average particle size of the mixture after calcining obtained after pulverization is, for example, 0.01 to 3.0 μm, preferably 0.1 to 2.0 μm. If the average particle size of the obtained mixture after calcining is 0.01 μm or more, it is preferable because a sufficient bulk specific gravity can be maintained and handling becomes easy. Moreover, if the average particle diameter of the mixture after calcining is 3.0 μm or less, it becomes easy to increase the density of the finally obtained sputtering target.
In addition, the average particle diameter of the mixture after calcining can be measured by the method and method described in JIS R 1619.

(B) Molding process The molding process is a process in which a mixture of raw material powders (a mixture after calcining when the calcining process is provided) is pressure-molded to form a compact. By this step, the mixture (or the mixture after calcining) is formed into a shape suitable as a sputtering target.

Examples of the molding process that can be used in this step include press molding, cold isostatic pressing, uniaxial pressing, mold molding, cast molding, and injection molding. In order to obtain a sintered body (sputtering target) having a high sintered density, it is preferable to perform molding with cold isostatic pressure (CIP) or the like.
In the molding process, molding aids such as polyvinyl alcohol, methylcellulose, polywax, and oleic acid may be used.

As the press molding, a known molding method such as a cold press method or a hot press method can be used. For example, the obtained mixed powder is filled in a mold and pressure-molded with a cold press machine. The pressure molding is performed at a pressure of 100 to 100,000 kg / cm ² , preferably 500 to 10,000 kg / cm ² at normal temperature (25 ° C.), for example.

In the cold press method, the mixed powder is filled in a mold and a molded body is produced and sintered. In the hot press method, the mixed powder is directly sintered in a mold.
As a dry-type cold press method, the raw material after the pulverization step is dried with a spray dryer or the like and then molded.
As the wet cold press method, for example, a filtration molding method (see JP-A-11-286002) is preferably used. This filtration molding method is a filtration molding die made of a water-insoluble material for obtaining a molded body by draining water from a ceramic raw material slurry under reduced pressure, and a lower molding die having one or more drain holes And a water-permeable filter placed on the molding lower mold, and a molding mold clamped from the upper surface side through a sealing material for sealing the filter. The formwork, the sealing material, and the filter are each assembled so that they can be disassembled. Using a filtration mold that drains water in the slurry under reduced pressure only from the filter surface side, a slurry composed of mixed powder, ion-exchanged water and an organic additive is prepared, and this slurry is poured into the filtration mold, Water from the slurry is drained under reduced pressure only from the filter surface side to produce a compact, and the resulting ceramic compact is dried and degreased and then sintered.

(C) Sintering Step Sintering after molding is performed by atmospheric pressure firing, HIP (hot isostatic pressure) firing or the like. The sintering temperature may be equal to or higher than the temperature at which the gallium compound reacts with the tin compound to produce a gallium stannate compound phase and a tin oxide phase, preferably 1200 to 1550 ° C., more preferably 1250 to 1500 ° C. 1500 ° C. is particularly preferred. If the sintering temperature is less than 1200 ° C., there is a possibility that gallium oxide-tin oxide based oxides such as Ga ₄ SnO ₈ , Ga ₄ Sn ₅ O ₁₆ and Ga ₃ Sn ₄ O ₁₂ may not be formed. If it exceeds 1550 ° C., the produced compound may be decomposed.
Although the sintering time depends on the sintering temperature, it is preferably 1 to 50 hours, particularly 2 to 30 hours.

Regarding the heating rate during sintering, 0.5 to 10 ° C./min is preferable, 1 to 8 ° C./min is more preferable, and 1 to 5 ° C./min is particularly preferable. When the temperature rising temperature is 10 ° C./min or less, sintering is not completed before diffusion, and solid solution substitution is expected to proceed. If it is 0.5 degreeC / min or more, the reaction of a gallium compound and a tin compound will accelerate | stimulate, and the uniformly disperse | distributed gallium stannate compound phase will precipitate. When the rate of temperature rise exceeds 10.0 ° C./min, the sintered body may be broken during the sintering process, or abnormally grown particles may be deposited, and when the sintered body is used as a sputtering target. Uniform film formation may not be possible.

Sintering may be performed in an oxidizing atmosphere. Examples of the oxidizing atmosphere include an atmosphere in which air or oxygen gas is introduced. In addition, it can also sinter under oxygen pressurization. In order to prevent evaporation of the gallium compound and the tin compound, it is preferable to carry out under oxygen inflow and oxygen pressurization.
By the above method, an oxide sintered body containing Ga and Sn as main components and including a gallium stannate compound phase and a tin oxide phase is obtained.

In the present invention, a reduction step may be provided as necessary after the sintering step (C). In some cases, the bulk resistance of the sintered body obtained in the sintering process can be made uniform as a whole by the reduction process.
Examples of the reduction method include a method of circulating a reducing gas, a method of sintering in a vacuum, and a method of sintering in an inert gas.

As the reducing gas, for example, hydrogen, methane, carbon monoxide, a mixed gas of these gases and oxygen, or the like can be used.
As the inert gas, nitrogen, argon, a mixed gas of these gases and oxygen, or the like can be used.

The temperature during the reduction treatment is usually 100 to 800 ° C, preferably 200 to 800 ° C. The reduction treatment time is usually 0.01 to 10 hours, preferably 0.05 to 5 hours.
The pressure of the reducing gas or inert gas is, for example, 9800 to 1000000 Pa, preferably 98000 to 500000 Pa. In the case of sintering in a vacuum, the vacuum specifically means a vacuum of about 10 ⁻¹ to 10 ⁻⁸ Pa, preferably about 10 ⁻² to 10 ⁻⁵ a, and the residual gas is argon, nitrogen or the like. is there.

The oxide sintered body obtained by the above production method can be suitably used as a sputtering target. With this sputtering target, generation of arcing and nodules during film formation can be suppressed, and a crystalline oxide semiconductor film having excellent surface smoothness can be manufactured.

The sputtering target can be manufactured by cutting the sintered body into a shape suitable for mounting on a sputtering apparatus as necessary and attaching a mounting jig such as a backing plate.
The thickness of the sputtering target is usually 2 to 20 mm, preferably 3 to 12 mm, particularly preferably 4 to 6 mm. The surface of the sputtering target is preferably finished with a 200 to 10,000 diamond grindstone, and particularly preferably finished with a 400 to 5,000 diamond grindstone. It is preferable to use a No. 200-10,000 diamond grindstone because the sputtering target will not break. Further, a plurality of sputtering targets may be attached to one backing plate to substantially form one target. Examples of the backing plate include those made of oxygen-free copper.

In the present invention, an oxide semiconductor thin film or an oxide conductive thin film can be obtained by forming a film by a sputtering method or an ion plating method using the target made of the sintered body of the present invention described above.
These films are amorphous and have transparency. The light transmittance can be, for example, 82% or more. More preferably, a film of 84% or more, particularly preferably 85% or more is obtained.
In particular, an oxide semiconductor film formed by a sputtering method is preferable.

As a sputtering method, an RF magnetron sputtering method, a DC magnetron sputtering method, an AC magnetron sputtering method, a pulsed DC magnetron sputtering method, or the like is preferably used.
Regarding sputtering conditions, the oxygen partial pressure during film formation is preferably 1 vol% or more and less than 20% vol. If it is less than 1% vol, the film immediately after film formation may have conductivity, and use as an oxide semiconductor may be difficult. On the other hand, if it is 20 vol% or more, the film may become an insulator and it may be difficult to use it as an oxide semiconductor. Preferably, it is 3 to 10 vol%.

The substrate temperature during film formation is preferably from room temperature to 300 ° C. If it is set below the room temperature or above 300 ° C., the cooling / heating is too expensive. Preferably, the temperature is from room temperature (no substrate heating) to 200 ° C. In the case of continuous sputtering, the substrate may be heated by the plasma being sputtered, and in the case of a film substrate or the like, it is preferable to carry out cooling while keeping the temperature at about room temperature.
In the case where a film is formed over a heat-resistant substrate such as a glass substrate, the oxide semiconductor film can be stably and uniformly manufactured by heating the substrate to 150 ° C. to 350 ° C. after sputtering. If it is less than 150 degreeC, the stabilization effect is small by heating, and if it exceeds 350 degreeC, heating may be too expensive. 200 ° C to 300 ° C is preferred.
The heating time is preferably 10 minutes to 120 minutes. In 10 minutes, the heating effect may not be seen, and in more than 120 minutes, the heating time may be too long and too expensive. 30 minutes to 90 minutes is preferred.

The heating atmosphere is preferably an air atmosphere or an oxygen circulation atmosphere.
In the case of an oxide semiconductor thin film, it is considered that electron carriers present in the semiconductor thin film are generated by oxygen vacancies, and the concentration of electron carriers is proportional to the concentration of oxygen vacancies. Therefore, when the electron carrier concentration is controlled, it is necessary to control the oxygen deficiency concentration. When heat treatment is performed in an atmosphere having a higher oxygen concentration, the oxygen deficiency concentration can be reduced at a lower heating temperature, which is economical. However, when heated to a high temperature in pure oxygen, oxygen vacancies may disappear completely and become an insulator. A preferable oxygen concentration is 5% to 50%, and particularly preferably 10% to 30%.
In the case of an oxide conductive thin film, the preferable oxygen concentration is 0 to 50%, preferably 0.1 to 30%, more preferably 0.5 to 20%.

Examples of the present invention will be described below. In addition, the measuring method of the sample obtained in the Example is as follows.
(1) Bulk resistance of oxide sintered body It measured with Mitsubishi Chemical Loresta or Hiresta.
(2) Density of sintered body The theoretical density was calculated from the raw material mixture, and the relative density [(actual density) / (theoretical density)] compared with the actual density was obtained. The density was measured by Archimedes method using a sample piece cut into a 2 cm square size using water as a solvent.
(3) Specific Resistance and Light Transmittance of Thin Film The specific resistance was measured with a Mitsubishi Chemical Loresta. The light transmittance was measured as 400 nm to 800 nm for a 100 nm thin film prepared on a glass substrate with a visible spectrophotometer (Shimadzu UV3100), and the average transmittance was determined.

Example 1
(1) Production of oxide sintered body 300 g of gallium oxide, 300 g of tin oxide and 5 g of zinc oxide were dispersed in ion-exchanged water, and pulverized and mixed for 10 hours in a bead mill.
Next, the obtained slurry was dried and granulated with a spray dryer. This powder was charged into a 140 mmφ mold and pre-molded at a pressure of 100 kg / cm ^{2 with} a mold press molding machine.
Next, it compacted with the pressure of 4 t / cm < ² > with the cold isostatic press molding machine.
The molded body was heated at a temperature increase rate of 500 ° C. or higher at 1.0 ° C./min. And sintered at 1400 ° C. for 15 hours to obtain a sintered body.
The result of examining the composition of this sintered body with an ICP apparatus was as follows.
Ga / (Ga + Sn) = 0.44 (atomic ratio)
Sn / (Ga + Sn) = 0.56 (atomic ratio)
Zn / (Ga + Sn + Zn) = 0.01 (atomic ratio)
The X-ray diffraction result of the obtained sintered body is shown in FIG. From this result, the peak of the tin oxide phase and the gallium stannate compound phase was observed. It can be seen that the sintered body is composed of the Ga ₄ SnO ₈ and SnO ₂ phases. The relative density of this sintered body was 91%.

The bulk resistance of the sintered body was 0.160 Ωcm.
Further, the dispersion state of Ga, Sn, and Zn was confirmed by EPMA measurement in a visual field range of 50 microns. As a result, there were a phase in which Ga and Sn were dispersed and a phase in which only Sn was present, and Zn was dispersed in a phase in which only Sn was present, that is, SnO ₂ . As a result, the dispersion state of Ga and Sn was substantially uniform, and the average particle diameters of the tin oxide phase and the gallium stannate phase were 3.5 μm and 4.2 μm, respectively.
The sintered body on which the target was polished was subjected to a three-point bending test, and the strength was measured. Based on the results, a cumulative failure probability with respect to the bending strength by the median rank method and a Weibull plot with a single mode were prepared, and a Weibull coefficient (m value) indicating variation in the failure probability was obtained. As for the Weibull coefficient, an m value of 10.2 was obtained by obtaining a linear regression line. This means that the larger the Weibull coefficient, the more the non-destructive stress does not vary, but the variation is small and it can be confirmed that the material is stable.

(2) Evaluation of thin film The sintered body of (1) was ground and polished to obtain a sputtering target having a diameter of 4 inches and a thickness of 5 mm. Using this sputtering target, a thin film having a thickness of 100 nm was produced on a glass substrate with an Shimadzu HSM-552 sputtering apparatus in an O ₂ / (O ₂ + Ar) = 2% atmosphere, a sputtering pressure of 0.2 Pa, an RF output of 100 W. did.
This thin film was heated at 200 ° C. for 1 hour.
When the thin film sample after heating was measured by X-ray diffraction (Rigaku Ultimate III), it was amorphous.
Further, when the average surface roughness of the surface of the thin film was measured with an AFM apparatus (JSPM-4500, manufactured by JEOL Ltd.) over a range of 10 microns × 10 microns square, it was very flat at 0.2 nm.
The light transmittance of the thin film was 88%.
The specific resistance in the hole measurement of the thin film was 10 Ωcm, and the carrier concentration was 1.6 × 10 ¹⁶ / cm ³ .
In addition, the hall | hole measuring apparatus and its measurement conditions were as follows.
・ Hall measuring device manufactured by Toyo Technica: Resi Test 8310
・ Measurement conditions Measurement temperature: Room temperature (25 ℃)
Measurement magnetic field: 0.5T
Measurement current: 10 ⁻¹² to 10 ⁻⁴ A
Measurement mode: AC magnetic field

When the thin film was used as a thin film transistor semiconductor element, semiconductor characteristics were obtained when measured at room temperature.

(3) Nodule and Sputter Discharge Evaluation The sputtering target obtained in (2) was mounted on a sputtering apparatus in the same manner as in (2), and was continuously sputtered at an RF output of 400 W for 8 hours. As a result, no nodules were generated.

Example 2
(1) Production of oxide sintered body 300 g of gallium oxide, 300 g of tin oxide, and 5 g of zinc oxide were dispersed in ion-exchanged water and pulverized and mixed in a bead mill for 72 hours in order to improve dispersibility.
Next, the obtained slurry was dried and granulated with a spray dryer. This powder was charged into a 140 mmφ mold, and preformed at a pressure of 100 kg / cm ² by a mold press molding machine.
Next, it compacted with the pressure of 4 t / cm < ² > with the cold isostatic press molding machine.
The molded body was heated at a temperature increase rate of 500 ° C. or higher at 1.0 ° C./min. And sintered at 1400 ° C. for 15 hours to obtain a sintered body.
The result of examining the composition of this sintered body with an ICP apparatus was as follows.
Ga / (Ga + Sn) = 0.44 (atomic ratio)
Sn / (Ga + Sn) = 0.56 (atomic ratio)
Zn / (Ga + Sn + Zn) = 0.01 (atomic ratio)
From the X-ray diffraction result of the obtained sintered body, peaks of a tin oxide phase and a gallium stannate compound phase were observed. It can be seen that the sintered body is composed of the Ga ₄ SnO ₈ and SnO ₂ phases. When the density of this sintered body was examined by the Archimedes method, the relative density was 92%.
The bulk resistance of the sintered body was 0.160 Ωcm.
Also, when the dispersion state of Ga, Sn, and Zn was confirmed by EPMA measurement in a 50 micron visual field range, there were a phase in which Ga and Sn were dispersed and a phase in which only Sn was present, as in Example 1. Zn was dispersed in a phase having only Sn, that is, SnO ₂ . As a result, the dispersion state of Ga and Sn was substantially uniform, and the average particle diameters of the tin oxide phase and the gallium stannate phase were 3.8 μm and 4.3 μm, respectively.
As in Example 1, a three-point bending test was performed on the polished sintered body and the strength was measured. As a result, the Weibull coefficient (m value) was 10.5. There is no variation in the maximum value, and it can be confirmed that the material is stable with little variation.

(2) Evaluation of thin film The sintered body of (1) was ground and polished to obtain a sputtering target having a diameter of 4 inches and a thickness of 5 mm. Using this sputtering target, a thin film having a thickness of 100 nm was formed on a glass substrate with an Shimadzu HSM-552 sputtering apparatus in an atmosphere having an O ₂ / (O ₂ + Ar) ratio of 10%, a sputtering pressure of 0.2 Pa, an RF output of 100 W. It was prepared.
This thin film was heated at 200 ° C. for 1 hour.
When the thin film sample after heating was measured by X-ray diffraction, it was amorphous.
The surface of the thin film was very flat with an AFM apparatus and Ra was 0.2 nm.
The light transmittance of the thin film was 88%.
The specific resistance in the hole measurement of the thin film was ¹⁵ Ωcm, and the carrier concentration was 1.5 × 10 ¹⁵ / cm ³ .
When the thin film was used as a thin film transistor semiconductor element, semiconductor characteristics were obtained when measured at room temperature.

Example 3
100 g of gallium oxide, 400 g of tin oxide, 10 g of niobium oxide, and a temperature increase rate of 500 ° C. or higher is 2.0 ° C./min. An oxide sintered body was produced in the same manner as in Example 1 except that.
The composition of this sintered body was as follows.
Ga / (Ga + Sn) = 0.25
Sn / (Ga + Sn) = 0.75
Nb / (Ga + Sn + Nb) = 0.01

The X-ray diffraction result of the obtained sintered body is shown in FIG.
In this result, the tin oxide phase was mainly observed, and the peak of the gallium stannate compound was also observed.
The bulk resistance of the sintered body was 0.030 Ωcm.
As a result of confirming the dispersion state of Ga, Sn, and Nb by EPMA measurement, the dispersion state was substantially uniform.
The relative density of the sintered body was 94%. When the Weibull coefficient (m value) was determined in the same manner as in Example 1, it was 10.6. It can be confirmed that the Weibull coefficient is a larger value, there is little variation, and the material is stable and has high strength.

(2) Evaluation of thin film A sputtering target was produced in the same manner as in Example 1 except that the sintered body produced in (1) was used, and a thin film was produced. This thin film was a transparent conductive film.
The resulting thin film had a light transmittance of 86%.
The specific resistance in the hole measurement of the thin film was 1.5 × 10 ⁻³ Ωcm, the carrier concentration was 1.2 × 10 ²⁰ cm ⁻³ , and a transparent and low resistance thin film was obtained.
Further, when the average surface roughness of the surface of the thin film was measured with an AFM apparatus, Ra was as extremely flat as 0.2 nm.

(3) Nodule evaluation The sputtering target obtained in (2) was evaluated in the same manner as in Example 1. As a result, no nodules were generated.

Example 4
100 g of gallium oxide, 400 g of tin oxide and 10 g of niobium oxide were weighed and dispersed in ion-exchanged water, and pulverized and mixed in a bead mill for 72 hours in order to improve dispersibility.
Next, the obtained slurry was dried and granulated with a spray dryer. This powder was charged into a 140 mmφ mold, and preformed at a pressure of 100 kg / cm ² by a mold press molding machine.
Next, it compacted with the pressure of 4 t / cm < ² > with the cold isostatic press molding machine.
The molded body was heated at a heating rate of 500 ° C. or higher at 3.0 ° C./min. And sintered at 1550 ° C. for 72 hours to obtain a sintered body.
The composition of this sintered body was as follows.
Ga / (Ga + Sn) = 0.25
Sn / (Ga + Sn) = 0.75
Nb / (Ga + Sn + Nb) = 0.01

The X-ray diffraction result of the obtained sintered body is shown in FIG.
In this result, the tin oxide phase was mainly observed, and the peak of the gallium stannate compound was also observed.
The bulk resistance of the sintered body was as low as 0.010 Ωcm.
As a result of confirming the dispersion state of Ga, Sn, and Nb by EPMA measurement, the dispersion state was substantially uniform.
The relative density of the sintered body was 95%. When the Weibull coefficient (m value) was determined in the same manner as in Example 1, it was 10.9. It can be confirmed that the Weibull coefficient is a larger value, there is little variation, and the material is stable and has high strength.

(2) Evaluation of thin film A sputtering target was produced in the same manner as in Example 1 except that the sintered body produced in (1) was used, and a thin film was produced. This thin film was a transparent conductive film.
The resulting thin film had a light transmittance of 87%.
The specific resistance in the hole measurement of the thin film was 1.3 × 10 ⁻³ Ωcm, the carrier concentration was 1.5 × 10 ²⁰ / cm ³ , and a transparent and low-resistance thin film was obtained.
Further, when the average surface roughness of the surface of the thin film was measured with an AFM apparatus, Ra was as extremely flat as 0.2 nm.

(3) Nodule evaluation The sputtering target obtained in (1) was evaluated in the same manner as in Example 1. As a result, no nodules were generated.

Example 5
100 g of gallium oxide, 400 g of tin oxide, 10 g of niobium oxide and 10 g of aluminum oxide were weighed and dispersed in ion-exchanged water, and pulverized and mixed in a bead mill for 72 hours in order to improve dispersibility.
Next, the obtained slurry was dried and granulated with a spray dryer. This powder was charged into a 140 mmφ mold, and preformed at a pressure of 100 kg / cm ² by a mold press molding machine.
Next, it compacted with the pressure of 4 t / cm < ² > with the cold isostatic press molding machine.
The molded body was heated at a heating rate of 500 ° C. or higher at 2.0 ° C./min. And sintered at 1550 ° C. for 72 hours to obtain a sintered body.
The composition of this sintered body was as follows.
Ga / (Ga + Sn) = 0.25
Sn / (Ga + Sn) = 0.75
Nb / (Ga + Sn + Nb + Al) = 0.01
Al / (Ga + Sn + Nb + Al) = 0.01

The X-ray diffraction result of the obtained sintered body is shown in FIG.
From this result, the tin oxide phase was mainly observed, and the peak of the gallium stannate compound was also observed.
The sintered body had a low bulk resistance of 9.7 × 10 ⁻³ Ωcm.
As a result of confirming the dispersion state of Ga, Sn, Nb, and Al by EPMA measurement, the dispersion state was substantially uniform. From the EXAFS measurement at the Nb-K end, it was confirmed that Nb was positive pentavalent and was substituted with SnO ₂ phase.
The relative density of the sintered body was 96%. When the Weibull coefficient (m value) was determined in the same manner as in Example 1, it was 11.2. It can be confirmed that the Weibull coefficient is a larger value, there is little variation, and the material is stable and has high strength.

(2) Evaluation of thin film A sputtering target was produced in the same manner as in Example 1 except that the sintered body produced in (1) was used, and a thin film was produced. This thin film was a transparent conductive film.
The resulting thin film had a light transmittance of 87%.
The specific resistance of the thin film in hole measurement was 1.25 × 10 ⁻³ Ωcm, the carrier concentration was 2.0 × 10 ²⁰ / cm ³ , and a transparent and low-resistance thin film was obtained.
Further, when the average surface roughness of the surface of the thin film was measured with an AFM apparatus, Ra was as extremely flat as 0.2 nm.

Examples 6 and 7
A sintered body was produced and evaluated in the same manner as in Example 1 except that the mixing ratio of the raw materials was changed as shown in Table 1. The results are shown in Tables 1 and 2.
In the sintered bodies obtained in Examples 6 and 7, the peaks of the tin oxide phase and the gallium stannate compound were observed from X-ray diffraction, and the dispersion state of Ga, Sn, and Zn was confirmed by EPMA measurement. As a result, the dispersion state was substantially uniform.

Comparative Example 1
475 g of tin oxide and 25 g of gallium oxide were weighed, added with an aqueous polyvinyl alcohol solution, granulated, and mixed for 20 hours using a ball mill. The mixed powder was filled into a press die having a size of 400 mm × 800 mm and press-molded at a pressure of 500 Kg / cm ² . The molding density of the molded body at this time was 3.3 to 3.9 g / cm ³ . This was dried at 80 ° C. for 15 hours and then degreased at 200 ° C. to 600 ° C., and the temperature rising rate of 500 ° C. or higher was 12 ° C./min. And was sintered for 4 hours at 1500 ° C. in an oxygen atmosphere.
The sintered body thus obtained was processed to produce a sputtering target having a size of 300 mm × 600 mm × 8 mm.
The density of this sputtering target was 5.08 g / cm ³ and the relative density was 88%. The bulk resistance was too high to be measured.
Further, when the Weibull coefficient (m value) was determined in the same manner as in Example 1, it was 9.2. It was a material with low Weibull coefficient, large variation, and insufficient strength.
When this target was used to produce a thin film in the same manner as in Example 1, the specific resistance was 8.0 × 10 ⁻² Ωcm and the carrier concentration was 1.0 × 10 ²⁰ / cm ³ . The light transmittance was 80%.

Comparative Example 2
A sintered body was obtained in the same manner as in Example 1 except that 475 g of tin oxide and 25 g of niobium oxide were used.
The relative density of the sintered body was 88%, and the bulk resistance was 9.8 × 10 ⁻³ Ωcm.
When a thin film was produced using this sintered body in the same manner as in Example 1, the specific resistance was 4.5 × 10 ⁻¹ Ωcm. The light transmittance was 76%.

Comparative Example 3
A sintered body was obtained in the same manner as in Example 1 except that 475 g of tin oxide and 25 g of antimony oxide were used. In addition, since antimony oxide has a large amount of evaporation when the temperature is high, the temperature rising rate of 500 ° C. or higher is 15 ° C./min. The sintering temperature was 1000 ° C. and sintering was performed for 15 hours.
The density of the sintered body was 73% and the bulk resistance was 120 Ωcm.
When this sintered body was used to produce a thin film in the same manner as in Example 1, the specific resistance was 5.6 × 10 ⁻² Ωcm. The light transmittance was 79%.

Comparative Example 4
A sintered body was obtained in the same manner as in Example 1 except that 10 g of tin oxide and 490 g of gallium oxide were used. The composition of this sintered body was as follows.
Ga / (Ga + Sn) = 0.99
Sn / (Ga + Sn) = 0.01

The relative density of this sintered body was 88%. The bulk resistance was too high to be measured.
In the X-ray diffraction result of the sintered body, only the gallium oxide phase was observed as the crystal phase.

When a thin film was produced in the same manner as in Example 1 using this sintered target, the specific resistance was 5.6 × 10 ⁴ Ωcm and the light transmittance was 88%.
Moreover, when the semiconductor element was produced, the semiconductor characteristic was not shown.
Moreover, nodule evaluation was performed on the target in the same manner as in Example 1 (3). As a result, arcing was observed, and the target cracked in 1 hour, making it impossible to discharge.

Comparative Example 5
A sintered body was obtained in the same manner as in Example 1 except that 495 g of tin oxide and 5 g of gallium oxide were used. The composition of this sintered body was as follows.
Ga / (Ga + Sn) = 0.01
Sn / (Ga + Sn) = 0.99

The relative density of this sintered body was 77%, and it was found that the sintered density did not increase. This is because the amount of gallium oxide is too small.
Further, the bulk resistance was 1800 Ωcm, and from the X-ray diffraction results, only the tin oxide phase was observed as the crystal phase.

Using this sintered target, a thin film was produced in the same manner as in Example 1 (2). The specific resistance was 3.3 × 10 ⁻² Ωcm. The thin film was colored brown and its light transmittance was 65%.
Moreover, nodule evaluation was performed on the target in the same manner as in Example 1 (3). As a result, abnormal discharge was observed during the sputter discharge, and a large amount of nodules and bubble voids were observed on the surface of the target after the nodule test.

Comparative Example 6
A sintered body was obtained in the same manner as in Example 1 except that 300 g of tin oxide and 300 g of gallium oxide were used.
The X-ray diffraction result of the obtained sintered body is shown in FIG.

The relative density of this sintered body was 85%. The bulk resistance was too high to be measured.
Further, when the Weibull coefficient (m value) was determined in the same manner as in Example 1, it was 8.8.

Using the target made of this sintered body, nodule evaluation was performed in the same manner as in Example 1 (3). As a result, stable discharge could not be performed and sputtering could not be performed.

Comparative Example 7
A sintered body was obtained in the same manner as in Example 1 except that 400 g of tin oxide and 100 g of gallium oxide were used.
The X-ray diffraction result of the obtained sintered body is shown in FIG.

The relative density of this sintered body was 89%. The bulk resistance was too high to be measured.
Further, when the Weibull coefficient (m value) was determined in the same manner as in Example 1, it was 9.5.

Using the target made of this sintered body, nodule evaluation was performed in the same manner as in Example 1 (3). As a result, stable discharge could not be performed and sputtering could not be performed.
Table 1 shows the raw materials and physical properties of the oxide sintered bodies produced in the examples and comparative examples described above, and Table 2 shows the evaluation of the physical properties and film forming properties of the oxide films.

With the oxide sintered body of the present invention, a sputtering target that does not generate nodules or arcing can be produced.
The sputtering target of the present invention is suitable as a material for forming an oxide film. For example, it can be used for semiconductor layers of thin film transistors, formation of oxide semiconductors, transparent electrodes, and the like.
The entire contents of the documents described in this specification are incorporated herein by reference.

Claims

Ga 4 containing SnO 8, Ga 4 Sn 5 O 16 and Ga 3 Sn 4 O 12 and one or more stannate gallium compound phase selected from a tin oxide phase,
An oxide sintered body in which at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum, and antimony is dispersed.
The oxide sintered body according to claim 1, wherein the ratio [Ga / (Ga + Sn)] of the gallium element to the total of the gallium element and the tin element is 0.01 to 0.80 in atomic ratio.
The oxide sintered body according to claim 1 or 2, wherein at least one element selected from niobium, tantalum and antimony is dispersed.
The at least one element selected from zinc, aluminum, silicon, indium, germanium, titanium, niobium, tantalum, tungsten, molybdenum, and antimony is solid solution substituted in the tin oxide phase. The oxide sintered body described.
The oxide sintered body according to claim 4, wherein the amount of the element substituted by solid solution is 0.08 or less in atomic ratio with respect to the total amount of all metal elements.
6. The oxide sintered body according to claim 1, wherein an average particle diameter of the tin oxide phase or the gallium stannate compound phase is 5 μm or less.
Mixing a gallium compound and a tin compound;
Molding the mixture obtained in the above step to obtain a molded product;
The method for producing an oxide sintered body according to any one of claims 1 to 6, further comprising a step of sintering the molded product obtained in the step at 1200 to 1550 ° C.
The method for producing an oxide sintered body according to claim 7, wherein in the sintering step, the sintering temperature is set to a sintering temperature of 0.5 ° C / min or more.
An oxide film obtained by forming a film by a sputtering method or an ion plating method using the target comprising the oxide sintered body according to any one of claims 1 to 7.
The oxide film according to claim 9 formed by a sputtering method.