JP2010202451A - METHOD FOR PRODUCING In-Ga-Zn-BASED COMPOSITE OXIDE SINTERED COMPACT - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an In-Ga-Zn-based composite oxide sintered compact where the In-Ga-Zn-based composite oxide sintered compact composed mainly of the crystal of a compound denoted as In<SB>2</SB>Ga<SB>2</SB>ZnO<SB>7</SB>is obtained as an IGZO sintered compact. <P>SOLUTION: The method for producing the In-Ga-Zn-based composite oxide sintered compact has a mixing step to pulverize a mixture of the oxides of indium (In), gallium (Ga) and zinc (Zn) in a molar ratio of 1:1:1 respectively and obtain raw material powders, a calcining step to calcine the raw material powders at a predetermined temperature and obtain calcined powders, a forming step to form a formed body having a predetermined size with the calcined powders and a baking step to bake the formed body at 1,500-1,600°C for 4 hours or more in a predetermined atmosphere and obtain the sintered compact. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for producing an In—Ga—Zn-based composite oxide sintered body for forming a transparent thin film suitable for TFTs, transparent electrodes, and the like, and more specifically, a crystal of a compound represented by In ₂ Ga ₂ ZnO _7. The present invention relates to a method for producing an In—Ga—Zn-based composite oxide sintered body.

  Conventionally, amorphous silicon films have been mainly used as channel layers of thin film transistors (TFTs) and transparent thin films for transparent electrodes in liquid crystal display devices and thin film electroluminescence display devices such as organic EL.

  However, in recent years, as this transparent thin film, an amorphous semiconductor film containing In—Ga—Zn-based composite oxide (IGZO) as a main component has been attracting attention because of its advantage of higher carrier mobility than the amorphous silicon film. (For example, Patent Documents 1 and 2).

As an amorphous semiconductor film mainly composed of IGZO, conventionally, a material for forming a transparent thin film such as a sputtering target mainly made of an IGZO sintered body mainly composed of InGaZnO ₄ is used. An amorphous semiconductor film containing InGaZnO ₄ as a main composition has been formed by various methods such as an ablation method and a sputtering method.

JP 2008-214697 A JP 2008-163441 A

  However, in recent years, an IGZO amorphous semiconductor film having a smaller ZnO content has been demanded as an amorphous semiconductor film having better carrier mobility and etching resistance in the manufacturing process of thin film transistors and the like. There is a need for a transparent thin film forming material (IGZO sintered body) such as a sputtering target for forming an amorphous semiconductor film.

Such IGZO sintered _body by forming an amorphous semiconductor film as a main composition of _In 2 _Ga 2 ZnO ₇ using the composite oxide sintered body represented by In ₂ Ga ₂ ZnO _7, the carrier Recently, it has been found that an IGZO amorphous semiconductor film having superior mobility and etching resistance in a manufacturing process of a thin film transistor or the like can be formed.

Such a complex oxide sintered body is generally prepared using In ₂ O ₃ , Ga ₂ O ₃ , ZnO having a molar ratio of 1: 1: 1 as a starting material, but a mixture or a compound with insufficient reaction. In this state, when the film is formed, only ZnO having a high vapor pressure is likely to evaporate first, so that the composition of the film is shifted, and the amorphous semiconductor having a stable and uniform In ₂ Ga ₂ ZnO ₇ as a main composition It becomes difficult to obtain a film. For this reason, the In ₂ Ga ₂ ZnO ₇ compound of the composite oxide sintered body in the present invention needs to have a single crystal phase as much as possible, but the molar ratio is 1: 1: 1 In ₂ O ₃ , Ga _{Even when 2} O ₃ and ZnO were used as starting materials, it was not possible to easily obtain a complex oxide sintered body having a single crystal phase mainly composed of crystals of a compound represented by In ₂ Ga ₂ ZnO ₇ .

  Further, in the production of a target for DC sputtering, which is the most common method for obtaining an amorphous semiconductor film, a target material that is as dense as possible and has a low specific resistance is required, but only a material with a density ratio of about 60 to 80% is obtained. Further, a target suitable for DC sputtering with a small specific resistance has not been obtained.

Therefore, the present invention is mainly a crystal of a compound represented by In ₂ Ga ₂ ZnO ₇ as a transparent thin film forming material that can form an excellent IGZO amorphous semiconductor film, that is, an IGZO sintered body, It is an object of the present invention to provide a method for producing an In—Ga—Zn-based composite oxide sintered body capable of obtaining a dense complex oxide sintered body having a small specific resistance.

The present inventor, in the prior art, uses In ₂ O ₃ , Ga ₂ O ₃ , and ZnO in a molar ratio of about 1: 1: 1 as a starting material, but why the compound represented by In ₂ Ga ₂ ZnO ₇ is used. Whether or not a complex oxide sintered body having a high density and a small specific resistance could not be obtained has been studied earnestly. As a result, the inventors have found that the above-described problems can be solved by the inventions of the following claims, and have reached the present invention.

The invention described in claim 1
A mixing step of mixing and pulverizing powders of oxides of indium (In), gallium (Ga) and zinc (Zn) at a molar ratio of 1: 1: 1 to obtain a raw material powder;
A calcining step of calcining the raw material powder at a predetermined temperature to obtain a calcined powder;
A molding step in which the calcined powder is formed into a molded body having a predetermined dimension;
And a firing step of firing the molded body at 1500 to 1600 ° C. for 4 hours or more in a predetermined atmosphere to form a sintered body, producing an In—Ga—Zn-based composite oxide sintered body Is the method.

The present inventor does not mix and mold the raw material powder as it is, but calcines the raw material powder temporarily, and further exceeds 1500 to 1450 ° C., which has been considered as the upper limit of the conventional firing temperature. It was found that by firing at a high temperature of 1600 ° C., a complex oxide sintered body mainly composed of crystals of a compound represented by In ₂ Ga ₂ ZnO ₇ and having a small specific resistance can be obtained.

When calcination is omitted, a heterogeneous phase of crystals is easily generated, and it is difficult to obtain a complex oxide sintered body mainly composed of crystals of a compound represented by In ₂ Ga ₂ ZnO ₇ . Moreover, a sintered body having a density ratio of 95% or more (ratio of the density of the sintered body to the theoretical density) cannot be obtained, and there is a possibility that cracks or the like may occur in the sintered body. Moreover, only a material having a large specific resistance can be obtained.

By carrying out calcination, ZnGa ₂ O ₄ is generated, and free ZnO that easily evaporates at the time of high-temperature firing and easily changes in composition is removed from the mixed powder before the forming step, so that an inhomogeneous phase of the crystal is formed. Generation | occurrence | production can be suppressed.

When the firing temperature is less than 1500 ° C., a composite oxide sintered body mainly composed of In ₂ Ga ₂ ZnO ₇ crystals, that is, a composite oxide sintered body close to an In ₂ Ga ₂ ZnO ₇ single-phase structure is obtained. And the content of crystals other than In ₂ Ga ₂ ZnO ₇ such as InGaZnO ₄ may be high, and a sintered body having a density ratio of 95% or more cannot be obtained. The specific resistance is also 10 ⁻² Ωcm or more.

On the other hand, if the firing temperature is 1500 ° C. or higher, In ₂ Ga ₂ ZnO ₇ crystals are generated. However, if the firing temperature exceeds 1600 ° C., the evaporation and reduction rate of ZnO becomes too large, which may lead to composition variation, bubble generation, increased deformation of the sintered body, and the like. If the firing temperature is 1500 to 1600 ° C., the evaporation and reduction rate of ZnO can be suppressed to about 1 to 10 mol%, and a high density close to the In ₂ Ga ₂ ZnO ₇ single phase structure (a density ratio of 95% or more) ) Composite oxide sintered body can be obtained.

The firing time is preferably 4 hours or longer. If it is less than 4 hours, In ₂ Ga ₂ ZnO ₇ crystals are not sufficiently formed, and the content of crystals other than In ₂ Ga ₂ ZnO ₇ such as InGaZnO ₄ increases, resulting in a highly non-uniform sintered body. It is more preferable that it is 12 to 24 hours because the content of crystals other than In ₂ Ga ₂ ZnO ₇ can be 5 wt% or less. Note that the firing is preferably performed in an air atmosphere or an inert gas atmosphere. When firing in an excessive oxygen atmosphere such as an oxygen stream, a specific resistance of 10 ⁻² Ωcm or less suitable for DC sputtering may not be obtained.

The invention described in claim 2
2. The In—Ga—Zn-based composite oxidation according to claim 1, further comprising a HIP process in which the sintered body is subjected to HIP treatment in an inert gas atmosphere at a temperature of 1450 to 1550 ° C. and a pressure of 98 MPa or more. This is a method for manufacturing a sintered product.

Mainly high-density In ₂ Ga ₂ ZnO ₇ crystal while suppressing evaporation of ZnO by applying HIP treatment (hot isostatic pressure treatment) in an inert gas atmosphere such as high-temperature and high-pressure Ar gas. A composite oxide sintered body can be obtained.

The invention according to claim 3
The calcined powder, molded body, or sintered body is hot-pressed at a temperature of 1450 to 1550 ° C. and a pressure of 19.6 MPa or higher without contacting a mold made of a reducing material in an inert gas atmosphere. It is a manufacturing method of the In-Ga-Zn type complex oxide sintered compact of Claim 1 characterized by the above-mentioned.

By carrying out hot pressing without bringing the calcined powder, molded body or sintered body into contact with a mold made of a reducing material such as carbon in an inert gas atmosphere such as high-temperature and high-pressure Ar gas, A composite oxide sintered body mainly composed of high-density In ₂ Ga ₂ ZnO ₇ crystal can be obtained while suppressing evaporation of ZnO.

The invention according to claim 4
4. In the mixing step, 1 to 10 mol% of zinc oxide (ZnO) is mixed in an amount of each oxide of indium (In) and gallium (Ga). It is a manufacturing method of the In-Ga-Zn system complex oxide sintered compact given in any 1 paragraph.

As described above, ZnO tends to evaporate during high-temperature firing. By mixing ZnO in an amount of 1 to 10 mol% in a large amount, ZnO necessary for forming a crystal of the In ₂ Ga ₂ ZnO ₇ compound can be surely secured, so In ₂ O ₃ , Ga ₂ O ₃ A sintered body having a molar ratio closer to 1: 1: 1 when converted to ZnO can be obtained.

The invention described in claim 5
The method for producing an In-Ga-Zn-based composite oxide sintered body according to any one of claims 1 to 4, wherein a reduction rate of ZnO in the firing step is 10 mol% or less. is there.

By reducing the reduction rate (evaporation rate) of ZnO in the firing process to 10% or less, a high-density and low-resistivity composite oxide sintered body close to the In ₂ Ga ₂ ZnO ₇ single-phase structure can be stably obtained. Obtainable.

According to the present invention, as an IGZO sintered body, a crystal of a compound represented by In ₂ Ga ₂ ZnO ₇ using In ₂ O ₃ , Ga ₂ O ₃ and ZnO having a molar ratio of 1: 1: 1 as a starting material. Thus, it is possible to easily provide a method for producing an In—Ga—Zn-based composite oxide sintered body that obtains a composite oxide sintered body mainly composed of.

3 is an X-ray diffraction pattern of the In—Ga—Zn-based composite oxide sintered body of Example 1. FIG. 4 is a SEM photograph of a fracture surface of the In—Ga—Zn-based composite oxide sintered body of Example 1. FIG. 3 is an X-ray diffraction diagram of an In—Ga—Zn-based composite oxide sintered body of Example 2. FIG. 4 is an X-ray diffraction diagram of an In—Ga—Zn-based composite oxide sintered body of Example 3. FIG.

  Hereinafter, the present invention will be described based on embodiments. Note that the present invention is not limited to the following embodiments. Various modifications can be made to the following embodiments within the same and equivalent scope as the present invention.

First, an outline of the raw material powder used in the present invention, a mixing method thereof and firing is described.
1. Raw Material Powder As described above, the sintered body of the present invention preferably has a low content of impurities such as Cd, Cu, and Na. For this reason, high purity In ₂ O ₃ , Ga ₂ O ₃ and ZnO powders having a purity of 99.99% or more are preferably used as the raw material powder.

2. Mixing raw material powder a. Mixing ratio As described above, among In ₂ O ₃ , Ga ₂ O ₃ , and ZnO, ZnO has a high vapor pressure and easily evaporates during firing. For this reason, in order to obtain a sintered body having a composition in which the ratio of In: Ga: Zn: O is closer to 2: 2: 1: 7, the mixed powder In ₂ O ₃ : Ga ₂ O ₃ : ZnO is used. It is effective to make the ZnO ratio 1-10 mol% higher than the 1: 1 ratio.

B. Mixing method Either a dry method or a wet method may be used for mixing the raw material powders. Specifically, mixing is performed using a normal ball mill or a planetary ball mill. In addition, a drying method such as natural drying or a spray dryer is preferably used for drying when mixing is performed by a wet mixing method.

3. Production of sintered body Production of the sintered body is carried out in two stages of calcination and firing.
I. Calcination As described above, the mixed powder is calcined before firing to generate ZnGa ₂ O ₄ in advance, and free ZnO is not contained, thereby suppressing the generation of a heterogeneous phase, and In ₂ Generation of a single phase of Ga ₂ ZnO ₇ can be promoted. Moreover, the density of a sintered compact can be raised and it can suppress that a crack generate | occur | produces in a sintered compact.

B. Firing a. Firing time, calcination temperature Firing is performed under conditions of a calcination temperature of 1500 to 1600 ° C. and a calcination time of 4 hours or more. High temperature baking at 1500 ° C. or higher is necessary for the production of In ₂ Ga ₂ ZnO ₇ . When the firing temperature is less than 1500 ° C., a sintered body having a density ratio of 95% or more cannot be obtained. On the other hand, when the temperature exceeds 1600 ° C., the composition of the sintered body may fluctuate due to evaporation of ZnO, bubbles may be generated in the sintered body, and deformation of the sintered body may increase. Further, if the firing time is less than 4 hours, the content of crystals other than In ₂ Ga ₂ ZnO ₇ such as InGaZnO ₄ may be increased. It is preferable to calcinate for 12 to 24 hours because the content of InGaZnO ₄ or the like can be reduced to 5 wt% or less.

b. Firing method Since it is necessary to obtain a high-density sintered body while suppressing evaporation of ZnO having a high vapor pressure during firing, HIP treatment using high-pressure Ar gas in addition to firing in the air or inert gas Hot pressing in an Ar gas atmosphere is preferably used.

Next, an Example demonstrates this invention concretely.
Example 1
In this example, a mixed powder of In ₂ O ₃ powder, Ga ₂ O ₃ powder, and ZnO powder was used as a material. After calcining the mixed powder, the calcined powder was molded by uniaxial pressure molding and then fired. This is an example in which a sintered body as a target was produced.

1. Grinding and mixing of material powders In ₂ O ₃ (purity 99.99%, average particle size about 3 μm), Ga ₂ O ₃ (purity 99.99%, average particle size about 2 μm), ZnO (purity 99.99%, average Each powder having a particle diameter of about 1 μm was weighed so as to have a molar ratio of 1: 1: 1.05, and pulverized and mixed for 10 hours using a ball mill apparatus. Note that ethyl alcohol was used as a dispersion medium. After milling and mixing, it was naturally dried.

2. Calcination Next, the obtained mixed powder was crushed and pulverized, put into an alumina crucible, and calcined at 1000 ° C. for 5 hours in an air atmosphere to obtain a calcined powder. As a result of X-ray diffraction measurement of the obtained calcined powder, diffraction peaks of ZnGa ₂ O ₄ and In ₂ O ₃ were observed, and no free ZnO peak was observed.

3. Molding and Firing Next, the obtained calcined powder was pressure-molded by uniaxial pressure molding to obtain a disk-shaped molded body having a diameter of 100 mm and a thickness of about 9 mm. The obtained molded body was fired at 1525 ° C. for 18 hours in an air atmosphere to obtain a sintered body. The obtained sintered body was contracted to a diameter of 80 mm (thickness was about 7 mm), and the appearance was blackish gray. In addition, no significant deformation or cracking was observed in the sintered body. Such a large deformation was not observed because it was fired at a temperature of 1525 ° C., ie, 1600 ° C. or less, and the generation of cracks was not observed because it was calcined.

4). Preparation of target Next, the obtained sintered body was processed into a diameter of 76.2 mm and a thickness of 5.0 mm to obtain a target.

5). Characteristic evaluation The target sintered body was subjected to X-ray diffraction measurement, composition analysis by ICP emission analysis, fracture surface observation by SEM, density and conductivity (volume resistance).

(1) X-ray diffraction measurement FIG. 1 shows an X-ray diffraction pattern of the sintered body measured by X-ray diffraction measurement. 2θ is 30.3 ° in FIG. 1, 35 °, 57 ° around like observed specific diffraction peak in _In 2 _Ga 2 ZnO ₇ to, the sintered body primarily generated by _In 2 _Ga 2 ZnO ₇ It was confirmed that Moreover, it turned out that it is a substantially single phase. Thus, a sintered body substantially consisting of a single phase of In ₂ Ga ₂ ZnO ₇ was obtained mainly by baking at a temperature of 1525 ° C., that is, 1500 ° C. or more, for 18 hours, that is, for 4 hours or more. This is because calcination was performed before firing.

(2) Composition analysis As a result of the composition analysis by the ICP method, the wt% of In, Ga, and Zn contained in the sintered body was In: 41.9%, Ga: 25.6%, and Zn: 11.7%, respectively. Met. When this result is converted into a molar ratio of In ₂ O ₃ , Ga ₂ O ₃ and ZnO, it becomes In ₂ O ₃ : Ga ₂ O ₃ : ZnO = 1.02: 1.02: 1.00, and the molar ratio is 1: It was confirmed that the deviation from 1: 1 was 0.02, that is, 2%.

(3) Observation of fracture surface by SEM FIG. 2 shows an SEM photograph obtained by observation of the fracture surface of the sintered body. From FIG. 2, it was found that the crystal grain size of the sintered body was approximately 20 to 30 μm, and the pores of 0.5 to 3 μm were only slightly scattered.

(4) Measurement of density and volume resistance The density of the sintered body obtained by the Archimedes method (underwater method) was measured. The theoretical density calculated from the lattice constant of the X-ray diffraction data of the sintered body was 6.494 g / cm ³ , and the ratio (density ratio) of the measured density to the theoretical density was calculated. Further, the volume resistance of the sintered body was measured by a four-point probe method using a resistivity meter (manufactured by Mitsubishi Oil Chemical Co., Ltd., Loresta). The measurement results of the density and volume resistance and the calculation results of the density ratio are shown in Table 1 together with the results of Example 2 and Example 3 to be described later.

(Example 2)
In this example, a calcined powder produced in the same manner as in Example 1 was molded by CIP (cold isostatic pressing) molding, then baked to produce a sintered body, and further subjected to HIP treatment to obtain a target. It is an example which produced the sintered compact used as follows.

1. Preparation of calcined powder A calcined powder was produced in the same manner as in Example 1.

2. Molding and Firing The obtained calcined powder was crushed and pulverized, and then pressure-molded by CIP molding to obtain a disk-shaped compact having a diameter of about 95 mm and a thickness of about 9 mm. The obtained molded body was fired at 1520 ° C. for 12 hours in an air atmosphere to obtain a sintered body. The obtained sintered body was contracted to a diameter of 80 mm (thickness was about 7.5 mm), and the appearance was blackish gray. Example 1 Results of measuring the density of the sintered body in the same manner as the water absorption is not observed, the density is 6.2 g / cm ^3, the density ratio with respect to the theoretical density of 6.494g / cm ³ are met 95% It was. Moreover, the X-ray diffraction measurement of the obtained sintered compact was performed.

3. X-ray diffraction measurement and composition analysis An X-ray diffraction diagram obtained by the measurement is shown in FIG. In FIG. 3, a diffraction peak inherent to In ₂ Ga ₂ ZnO ₇ was observed, and a diffraction peak inherent to InGaZnO ₄ was slightly observed when 2θ was around 20.5 °. As described above, it was confirmed from the X-ray diffraction measurement results that In ₂ Ga ₂ ZnO ₇ was mainly formed in the sintered body. It was also found that about several mol% of InGaZnO ₄ was mixed. Moreover, as a result of the composition analysis by ICP emission analysis, it was confirmed that the deviation from the 1: 1: 1 molar ratio of In ₂ O ₃ , Ga ₂ O ₃ , and ZnO was within 5%.

4). Preparation of target The obtained sintered body was subjected to HIP treatment in an Ar gas atmosphere at 1500 ° C., 152 MPa for 1 hour, and then processed into a diameter of 76.2 mm and a thickness of 5 mm to obtain a target.

5). Measurement of Density and Volume Resistance The density of the sintered body produced in the same manner as in Example 1 was measured, and the density ratio was calculated. Moreover, volume resistance was measured. The measurement results of the density and volume resistance and the calculation result of the density ratio are shown in Table 1 together with the results of Example 1 and Example 3 described later.

(Example 3)
In this example, a calcined powder produced in the same manner as in Example 1 was hot-pressed in an Ar gas atmosphere, and then annealed in an Ar gas atmosphere to produce a target sintered body. It is an example.

1. Preparation of calcined powder A calcined powder was produced in the same manner as in Example 1.

2. Molding and Firing After the obtained calcined powder was formed into a disk shape having a diameter of about 60 mm and a thickness of 15 mm by uniaxial pressure molding used in Example 1, the obtained compact was made of alumina-based oxide ceramics. Was used for hot pressing at 1500 ° C. and 24.5 MPa for 1 hour in an Ar gas atmosphere to obtain a sintered body. The thickness of the sintered body contracted by about 50% with respect to the molded body. The density ratio of the sintered body after the hot press treatment was 98%. Furthermore, the obtained sintered body was annealed at 1550 ° C. for 8 hours in an Ar gas atmosphere.

3. Production of target The sintered body that had been subjected to the annealing treatment was processed into a target having a diameter of 50.8 mm and a thickness of 6 mm.

4). Measurement of X-Ray Diffraction, Density and Volume Resistance A sintered body as a target produced in the same manner as in Example 1 was subjected to X-ray diffraction measurement and composition analysis by ICP emission analysis. Moreover, the density was measured and the density ratio was calculated. Furthermore, the volume resistance was measured. FIG. 4 shows an X-ray diffraction diagram. From FIG. 4, it was confirmed that In ₂ Ga ₂ ZnO ₇ was mainly generated in the sintered body. Further, a slight diffraction peak specific to InGaZnO ₄ was observed around 2θ of 20.5 °, and it was confirmed that InGaZnO ₄ was also present. Moreover, as a result of the composition analysis by ICP emission analysis, it was confirmed that the deviation from the 1: 1: 1 molar ratio of In ₂ O ₃ , Ga ₂ O ₃ , and ZnO was within 5%. The measurement results of density and volume resistance and the calculation results of the density ratio are shown in Table 1 together with the results of Example 1 and Example 2.

From Table 1, it turns out that the sintered compact produced in Examples 1-3 has a density ratio of 99% or more. In particular, in Example 2 fired using HIP treatment, a high density ratio of 100% is obtained. Moreover, it turns out that volume resistance is less than 10 ^<-2 > (omega | ohm) cm. Thus, the high density ratio of 95% or more was obtained because the effect by performing calcination was great.

  In addition, about the sintered compact produced in Examples 1-3, as a result of investigating content of Cd, Cu, Fe, K, Ni, and Pb by ICP emission analysis, these individual impurity elements were found for any target. The content of was 10 ppm or less, and the total content of these impurity elements was confirmed to be 100 ppm or less. Similarly, as a result of investigating the content of Na by ICP emission analysis, it was confirmed to be 2 to 20 ppm.

As described above in detail, since the sintered bodies produced in Examples 1 to 3 are sintered bodies mainly composed of In ₂ Ga ₂ ZnO ₇ , these sintered bodies are used as targets for In _2. When a film mainly composed of Ga ₂ ZnO ₇ is formed by sputtering or the like, the composition of the film is less likely to be shifted, the carrier mobility is large, and a stable amorphous semiconductor film can be manufactured.

  In addition, since the density ratio is 95% or more (porosity is 5% or less), the sintered body is high in density, so there are few defects as targets, stable sputtering such as discharge is performed, and there are few defects such as particles. A highly uniform amorphous semiconductor film can be manufactured.

Further, since the volume resistance is less than 10 ⁻² Ωcm, it is particularly suitable as a target for DC sputtering.

  Furthermore, since the amount of impurities is small, by forming a film using the sintered body of this example as a target, fluctuations in threshold voltage are suppressed, and an amorphous semiconductor having a stable operating state for TFTs and organic ELs A film can be made.

Claims (5)

A mixing step of mixing and pulverizing powders of oxides of indium (In), gallium (Ga) and zinc (Zn) at a molar ratio of 1: 1: 1 to obtain a raw material powder;
A calcining step of calcining the raw material powder at a predetermined temperature to obtain a calcined powder;
A molding step in which the calcined powder is a molded body having a predetermined size;
And a firing step of firing the molded body at 1500 to 1600 ° C. for 4 hours or more in a predetermined atmosphere to form a sintered body, producing an In—Ga—Zn-based composite oxide sintered body Method.   2. The In—Ga—Zn-based composite oxidation according to claim 1, further comprising a HIP process in which the sintered body is subjected to a HIP process in an inert gas atmosphere at a temperature of 1450 to 1550 ° C. and a pressure of 98 MPa or more. A method for manufacturing a sintered body.   Hot-pressing the calcined powder, molded body or sintered body at a temperature of 1450 to 1550 ° C. and a pressure of 19.6 MPa or more without bringing it into contact with a mold made of a reducing material in an inert gas atmosphere The manufacturing method of the In-Ga-Zn type complex oxide sintered compact of Claim 1 characterized by these.   4. In the mixing step, zinc oxide (ZnO) is mixed in an amount of 1 to 10 mol% more than indium (In) and gallium (Ga) oxides. The manufacturing method of the In-Ga-Zn type complex oxide sintered compact of any one of Claims 1.   The method for producing an In-Ga-Zn-based composite oxide sintered body according to any one of claims 1 to 4, wherein a reduction rate of ZnO in the firing step is 10 mol% or less.