Sintered body, sputtering target, oxide thin film, thin film transistor, electronic equipment, and method for producing sintered body

Abstract

A sintered body of an oxide containing an In element, a Ga element, and an Al element, wherein the atomic compositional ratio of the In element and the Al element satisfies formula (1) and formula (2).　[In] / ([In]+[Ga]+[Al])>0.70 … (1) [Al] / ([In]+[Ga]+[Al])>0.01 … (2)

Description

Sintered body, sputtering target, oxide thin film, thin film transistor, electronic device, and method for manufacturing sintered body

[0001] The present invention relates to a sintered body, a sputtering target, an oxide thin film, a thin film transistor, an electronic device, and a method for producing a sintered body.

[0002] To realize high-definition next-generation displays, high-mobility thin-film transistors (hereinafter, thin-film transistors may be referred to as TFTs) are required, and crystalline oxide semiconductors such as IGO (indium gallium oxide) are being considered as semiconductor materials for such TFTs. When an oxide semiconductor is used in a display, a TFT can be obtained by sputtering using a sputtering target having the same atomic composition as a sintered body of the oxide.

[0003] Furthermore, in order to realize large-sized displays such as televisions, there is a trend toward larger manufacturing equipment in terms of manufacturing costs, and the sintered bodies used as sputtering targets are also required to be able to achieve stable sputtering even in large equipment.

[0004] For example, Patent Document 1 describes a sputtering target that is substantially composed of oxides of indium and gallium, or oxides of indium and gallium with either or both of tin and aluminum. The sputtering target described in Patent Document 1 contains 100 ppm to 10,000 ppm of tin, if any, and 100 ppm to 10,000 ppm of aluminum, if any. The sputtering target described in Patent Document 1 has a volume of 14,000 μm ３ The porosity of the voids is 0.03% by volume or less, and the area of ​​the main surface is 25,000 mm ２ or more, and the thickness is 5 mm or more.

[0005] As described in Patent Document 1, a sputtering target made of a sintered body having an atomic composition ratio of Al element of 1 at% or less and a porosity of 0.03% by volume or less can realize stable sputtering even in a large size.

[0006] Recent developments have made it clear that stability in the TFT manufacturing process (small change in characteristics due to CVD (chemical vapor deposition) film formation, which is one of the processes after oxide semiconductor film formation) is required.

[0007] For example, Patent Document 2 discloses a compound having the composition formula (In ｘ Ga ｙ Al ｚ ) ２ O ３ and has a diffraction peak in a specific range of incident angles (2θ) observed by X-ray (Cu-Kα ray) diffraction measurement. Furthermore, Patent Document 2 describes a sputtering target using an oxide sintered body consisting of the crystalline compound A alone.

[0008] The composition formula (In ｘ Ga ｙ Al ｚ ) ２ O ３ A sputtering target containing crystalline compound A represented by the formula (I) can realize stable sputtering, is stable in the TFT manufacturing process, and can also meet the demand for TFT (thin film transistor) performance with high mobility.

[0009] Japanese Patent No. 5997690 International Publication No. 2020 / 027243

[0010] In recent years, not only for panels for large displays (televisions), but also for panels for medium-sized displays (notebooks and tablets), manufacturing using large equipment using glass substrates with dimensions of 2200 mm x 2400 mm or more is becoming mainstream. Furthermore, there is a demand for higher definition and narrower frame widths in medium-sized display applications, and to achieve these, TFTs are required to have even higher performance (high mobility and high optical reliability). For this reason, oxide sintered bodies used as sputtering targets are required to have high mobility, TFT processability, and ease of in-plane uniformity control of performance (mobility and optical reliability), as well as sintered bodies that can be sputtered stably even in large equipment, and conventional sintered bodies have room for further improvement.

[0011] An object of the present invention is to provide a sintered body that can be stably sputtered even in a large-scale device, that has excellent TFT processability, and that can provide TFTs with high mobility and excellent in-plane uniformity of optical reliability; a sputtering target using the sintered body; an oxide thin film using the sputtering target; a thin-film transistor including the oxide thin film; and an electronic device including the thin-film transistor; and a method for manufacturing a sintered body that has excellent TFT processability, and that can provide TFTs with high mobility and excellent in-plane uniformity of optical reliability.

[0012] [1] A sintered body of an oxide containing In, Ga, and Al elements, wherein the atomic composition ratios of the In and Al elements satisfy the following formulas (1) and (2): [In] / ([In]+[Ga]+[Al])>0.70 (1) [Al] / ([In]+[Ga]+[Al])>0.01 (2)

[0013] [2] The sintered body according to [1], wherein, in a field of view when the sintered body is observed with a scanning electron microscope, the area ratio of pores to the area of ​​the field of view is 0.1% or less.

[0014] [3] The sintered body according to [1] or [2], wherein x is the atomic composition ratio of the Ga element expressed by {[Ga] / ([In]+[Ga]+[Al])}×100, and y is the atomic composition ratio of the Al element expressed by {[Al] / ([In]+[Ga]+[Al])}×100, and x and y are within the composition ranges, in atomic %, surrounded by the straight lines of the following (A1), (B0), (C1), (D1), and (E1): x≧4 (A1) x≦22.5 (B0) y>1 (C1) 6x+14y-98≧0 (D1) 4x+20y-180≦0 (E1).

[0015] [4] The sintered body according to [3], wherein the x and y are in the composition ranges enclosed by the straight lines of the following (A2), (B2), (C1), (D1), and (E1), in atomic percent: x≧8 (A2) x≦20 (B2)

[0016] [5] The sintered body according to any one of [1] to [4], which comprises a bixbyite structure containing an In element and a crystalline structure belonging to either a space group P1 or P-1, wherein the crystalline structure belonging to P1 is represented by the following crystalline structure parameter (X), and the crystalline structure belonging to P-1 is represented by the following crystalline structure parameter (Y). Crystal structure parameters (X): the lattice constants are a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α = 111.70 ± 0.50°, β = 107.70 ± 0.50°, and γ = 90.00 ± 0.50°; the crystal system is triclinic; the metal in the atomic configuration below owned by the space group P1 is any one of In, Ga, and Al, or any two or more of In, Ga, and Al, sharing the same atomic coordinates at a certain ratio; the atomic coordinates at which the metal is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01; and the atomic coordinates at which oxygen is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01. Atomic type: Metal, atomic coordinates (x=0.04, y=0.36, z=0.87) Atomic type: Metal, atomic coordinates (x=0.13, y=0.12, z=0.62) Atomic type: Metal, atomic coordinates (x=0.21, y=0.85, z=0.39) Atomic type: Metal, atomic coordinates (x=0.23, y=0.11, z=0.97) Atomic type: Metal, atomic coordinates (x=0.29, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.46, y=0.12, z=0.63) Atomic species: Metal, atomic coordinates (x=0.58, y=0.14, z=0.01) Atomic species: Metal, atomic coordinates (x=0.62, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.69, y=0.18, z=0.32) Atomic type: Metal, atomic coordinates (x=0.09, y=0.88, z=0.03) Atomic type: Metal, atomic coordinates (x=0.02, y=0.13, z=0.30) Atomic type: Metal, atomic coordinates (x=0.06, y=0.61, z=0.46) Atomic type: Metal, atomic coordinates (x=0.15, y=0.40, z=0.19) Atomic type: Metal, atomic coordinates (x=0.26, y=0.36, z=0.54) Atomic type: Metal, atomic coordinates (x=0.34, y=0.13, z = 0.30) Atomic type: Metal, atomic coordinates (x = 0.41, y = 0.61, z = 0.45) Atomic type: Metal, atomic coordinates (x = 0.48, y = 0.40, z = 0.23) Atomic type: Metal, atomic coordinates (x = 0.84, y = 0.39, z = 0.23) Atomic type: Metal, atomic coordinates (x=0.96, y=0.64, z=0.13) Atomic type: Metal, atomic coordinates (x=0.87, y=0.88, z=0.38) Atomic type: Metal, atomic coordinates (x=0.79, y=0.15, z=0.61) Atomic species: metal, atomic coordinates (x=0.77, y=0.89, z=0.03) Atomic type: Metal, atomic coordinates (x=0.71, y=0.36, z=0.89) Atomic type: Metal, atomic coordinates (x=0.54, y=0.88, z=0.37) Atomic type: Metal, atomic coordinates (x=0.42, y=0.86, z=0.99) Atomic type: Metal, atomic coordinates (x=0.38, y=0.36, z=0.89) Atomic type: Metal, atomic coordinates (x=0.31, y=0.82, z=0.68) Atomic type: Metal, atomic coordinates (x=0.91, y=0.12, z=0.97) Atomic species: Metal, atomic coordinates (x=0.98, y=0.87, z=0.70) Atomic species: Metal, atomic coordinates (x=0.94, y=0.39, z=0.54) Atomic species: Metal, atomic coordinates (x = 0.85, y = 0.60, z = 0.81) Atomic species: Metal, atomic coordinates (x = 0.74, y = 0.64, z = 0.46) Atomic species: Metal, atomic coordinates (x = 0.66, y = 0.87, z = 0.70) Atomic species: Metal, atomic coordinates (x = 0.59, y = 0.39, z = 0.55) Atomic species: Metal, atomic coordinates (x = 0.52, y = 0.60, z = 0.77) Atomic species: Metal, atomic coordinates (x = 0.16, y = 0.61, z = 0.77) Atomic species: Oxygen, atomic coordinates (x = 0.02, y = 0.73, z = 0.36) Atomic species: Oxygen, atomic coordinates (x = 0.03, y = 0.45, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.05, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.74, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.23, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.51, z = 0.09) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.13, y = 0.79, z = 0.17) Atomic species: oxygen, atomic coordinates (x = 0.19, y = 0.21, z = 0.84) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.23, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.25, y = 0.66, z = 0.49) Atomic species: oxygen, atomic coordinates (x = 0.27, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.30, y = 0.26, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.33, y = 0.44, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.39, y = 0.73, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.41, y = 0.24, z = 0.07) Atomic species: oxygen, atomic coordinates (x = 0.43, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.46, y = 0.51, z = 0.11) Atomic species: oxygen, atomic coordinates (x = 0.47, y = 0.79, z = 0.15) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.25, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.64, y = 0.03, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.66, y = 0.34, z = 0.23) Atomic species: oxygen, atomic coordinates (x = 0.72, y = 0.03, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.78, y = 0.51, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.25, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.96, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.98, y = 0.27, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.97, y = 0.55, z = 0.72) Atomic species: oxygen, atomic coordinates (x = 0.95, y = 0.98, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.90, y = 0.26, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.90, y = 0.77, z = 0.94) Atomic species: oxygen, atomic coordinates (x = 0.88, y = 0.49, z = 0.91) Atomic species: oxygen, atomic coordinates (x = 0.88, y = 0.53, z = 0.43) Atomic species: oxygen, atomic coordinates (x = 0.87, y = 0.21, z = 0.83) Atomic species: oxygen, atomic coordinates (x = 0.81, y = 0.79, z = 0.16) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.77, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.75, y = 0.34, z = 0.51) Atomic species: oxygen, atomic coordinates (x = 0.73, y = 0.98, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.70, y = 0.74, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.67, y = 0.56, z = 0.71) Atomic species: oxygen, atomic coordinates (x = 0.62, y = 0.98, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.61, y = 0.27, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.59, y = 0.76, z = 0.93) Atomic species: oxygen, atomic coordinates (x = 0.58, y = 0.53, z = 0.43) Atomic species: oxygen, atomic coordinates (x = 0.54, y = 0.49, z = 0.89) Atomic species: oxygen, atomic coordinates (x = 0.53, y = 0.21, z = 0.85) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.75, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.36, y = 0.97, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.34, y = 0.66, z = 0.77) Atomic species: oxygen, atomic coordinates (x = 0.28, y = 0.97, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.22, y = 0.49, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.75, z = 0.94) Atomic species: oxygen, atomic coordinates (x = 0.04, y = 0.98, z = 0.88) Crystal structure parameters (Y): Lattice constants are a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α = 111.70 ± 0.50°, β = 107.70 ± 0.50°, and γ = 90.00 ± 0.50°, the crystal system is triclinic, the metal in the following atomic configuration of the space group P-1 is any one of In, Ga, and Al, or any two or more of In, Ga, and Al, sharing the same atomic coordinates at a certain ratio, the atomic coordinates at which the metal is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01, the atomic coordinates at which oxygen is arranged are Includes the ranges of x±0.01, y±0.01, and z±0.01. Atomic species: Metal, atomic coordinates (x=0.04, y=0.36, z=0.87) Atomic species: Metal, atomic coordinates (x=0.13, y=0.12, z=0.62) Atomic type: Metal, atomic coordinates (x=0.21, y=0.85, z=0.39) Atomic type: Metal, atomic coordinates (x=0.23, y=0.11, z=0.97) Atomic type: Metal, atomic coordinates (x=0.29, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.46, y=0.12, z=0.63) Atomic type: Metal, atomic coordinates (x=0.58, y=0.14, z=0.01) Atomic type: Metal, atomic coordinates (x=0.62, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.69, y=0.18, z=0.32) Atomic type: Metal, atomic coordinates (x=0.09, y=0.88, z=0.03) Atomic type: Metal, atomic coordinates (x=0.02, y=0.13, z=0.30) Atomic type: Metal, atomic coordinates (x=0.06, y=0.61, z=0.46) Atomic type: Metal, atomic coordinates (x=0.15, y=0.40, z=0.19) Atomic type: Metal, atomic coordinates (x=0.26, y=0.36, z=0.54) Atomic type: Metal, atomic coordinates (x=0.34, y=0.13, z=0.30) Atomic type: Metal, atomic coordinates (x=0.41, y=0.61, z=0.45) Atomic species: Metal, atomic coordinates (x=0.48, y=0.40, z=0.23) Atomic species: Metal, atomic coordinates (x=0.84, y=0.39, z=0.23) Atomic species: oxygen, atomic coordinates (x = 0.02, y = 0.73, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.03, y = 0.45, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.05, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.74, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.23, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.51, z = 0.09) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.13, y = 0.79, z = 0.17) Atomic species: oxygen, atomic coordinates (x = 0.19, y = 0.21, z = 0.84) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.23, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.25, y = 0.66, z = 0.49) Atomic species: oxygen, atomic coordinates (x = 0.27, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.30, y = 0.26, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.33, y = 0.44, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.39, y = 0.73, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.41, y = 0.24, z = 0.07) Atomic species: oxygen, atomic coordinates (x = 0.43, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.46, y = 0.51, z = 0.11) Atomic species: oxygen, atomic coordinates (x = 0.47, y = 0.79, z = 0.15) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.25, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.64, y = 0.03, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.66, y = 0.34, z = 0.23) Atomic species: oxygen, atomic coordinates (x = 0.72, y = 0.03, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.78, y = 0.51, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.25, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.96, y = 0.02, z = 0.12).

[0017] [6] The sintered body according to [5], wherein when the weight ratios of the bixbyite structure containing In element, the crystal structure belonging to the space group P1 or P-1, and other crystal structures are calculated by performing Rietveld analysis on the spectrum obtained by performing X-ray diffraction measurement on the sintered body, the weight ratio of the crystals of the bixbyite structure containing In element to the crystals of the entire sintered body is 70% or more.

[0018] [7] The sintered body contains H element, and the atomic concentration of the H element contained in the sintered body is 1×10 １６ cm －３ That's it, 1 x 10 １８ cm －３ The sintered body according to any one of [1] to [6], wherein the sintered body has a molecular weight of less than 10 ...

[0019] [8] The sintered body contains a C element, and the atomic concentration of the C element contained in the sintered body is 1×10 １６ cm －３ That's it, 1 x 10 １８ cm －３The sintered body according to any one of [1] to [7], wherein the sintered body has a molecular weight of less than 10 ...

[0020] [9] The sintered body according to any one of [1] to [8], having a bending strength of 190 MPa or more.

[0021]

[10] A sputtering target using a sintered body of the oxide according to any one of [1] to [9].

[0022]

[11] An oxide thin film using the sputtering target according to

[10] .

[0023]

[12] A thin film transistor comprising the oxide thin film according to

[11] .

[0024]

[13] An electronic device comprising the thin film transistor according to

[12] .

[0025]

[14] A method for producing a sintered body of an oxide containing In, Ga, and Al elements, comprising the steps of: mixing and crushing indium oxide, gallium oxide, and aluminum oxide in a bead mill, granulating the mixture by a spray-drying method to obtain a granulated powder, and then classifying the granulated powder; molding the classified granulated powder to obtain a molded body; and sintering the molded body, wherein the atomic composition ratios of In and Al in the sintered body satisfy the following formulas (1) and (2): [In] / ([In]+[Ga]+[Al])>0.70 (1) [Al] / ([In]+[Ga]+[Al])>0.01 (2)

[0026] According to one aspect of the present invention, there are provided a sintered body that can be stably sputtered even in a large-scale device, that has excellent TFT processability, and that can provide TFTs with high mobility and excellent in-plane uniformity of optical reliability; a sputtering target using the sintered body; an oxide thin film using the sputtering target; a thin-film transistor including the oxide thin film; and an electronic device including the thin-film transistor. As well as this, there are provided a method for manufacturing a sintered body that has excellent TFT processability, that can provide TFTs with high mobility and excellent in-plane uniformity of optical reliability.

[0027] 5A is a graph showing the range of atomic composition of a sintered body according to one embodiment of the present invention. FIG. 5B is a graph showing the range of atomic composition of a sintered body according to one embodiment of the present invention. FIG. 5C is an example of an SEM image of a sintered body according to one aspect of a comparative example. FIG. 5A is an example of an enlarged SEM image of FIG. 3A. FIG. 5C is an example of an SEM image of a sintered body according to one embodiment of the present invention. FIG. 5D is an example of an enlarged SEM image of FIG. 3C. FIG. 5E is a perspective view showing the shape of a target according to one embodiment of the present invention. FIG. 5F is a perspective view showing the shape of a target according to one embodiment of the present invention. FIG. 5G is a longitudinal sectional view showing a state in which an oxide thin film is formed on a glass substrate. FIG. 5G is a view showing a state in which SiO is deposited on the oxide thin film of FIG. 5A. ２ 1 is a diagram showing a state in which a film has been formed. FIG. 2 is a longitudinal sectional view showing a thin film transistor according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing a thin film transistor according to an embodiment of the present invention. FIG. 4 is a longitudinal sectional view showing a thin film transistor according to an embodiment of the present invention. FIG. 5 is a longitudinal sectional view showing a quantum tunnel field effect transistor according to an embodiment of the present invention. FIG. 6 is a longitudinal sectional view showing another example of a quantum tunnel field effect transistor. FIG. 7 is a longitudinal sectional view illustrating a manufacturing procedure for a quantum tunnel field effect transistor. FIG. 8 is a longitudinal sectional view illustrating a manufacturing procedure for a quantum tunnel field effect transistor. FIG. 9 is a longitudinal sectional view illustrating a manufacturing procedure for a quantum tunnel field effect transistor. FIG. 10 is a longitudinal sectional view illustrating a manufacturing procedure for a quantum tunnel field effect transistor. FIG. 11 is a top view showing a display device using a thin film transistor according to an embodiment of the present invention. FIG. 12 is a circuit diagram illustrating a circuit of a pixel portion of a display device using a thin film transistor according to an embodiment of the present invention. FIG. 13 is a circuit diagram illustrating a circuit of a pixel portion of a display device using a thin film transistor according to an embodiment of the present invention. FIG. 14 is a diagram illustrating a circuit of a pixel portion of a solid-state imaging element using a thin film transistor according to an embodiment of the present invention.

[0028] Hereinafter, embodiments will be described with reference to the drawings, etc. However, it will be readily understood by those skilled in the art that the embodiments can be implemented in many different ways and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiments.

[0029] In the drawings, sizes, layer thicknesses, regions, etc. may be exaggerated for clarity. Therefore, the present invention is not limited to the illustrated sizes, layer thicknesses, regions, etc. Note that the drawings are schematic illustrations of ideal examples, and the present invention is not limited to the shapes, values, etc. shown in the drawings.

[0030] The ordinal numbers "first," "second," and "third" used in this specification are used to avoid confusion between components, and components that are not specified numerically are not limited in number.

[0031] In this specification and the like, the terms "film" or "thin film" and "layer" can be used interchangeably in some cases.

[0032] In the sintered body and oxide thin film of this specification and the like, the terms "compound" and "crystalline phase" can be interchangeable in some cases.

[0033] In this specification, the “oxide sintered body” may be simply referred to as the “sintered body.” In this specification, the “sputtering target” may be simply referred to as the “target.”

[0034] In this specification, "electrically connected" includes connection via "something that has some kind of electrical function." Here, "something that has some kind of electrical function" is not particularly limited as long as it allows electrical signals to be transmitted and received between the connected objects. For example, "something that has some kind of electrical function" includes electrodes, wiring, switching elements (such as transistors), resistive elements, inductors, capacitors, and other elements with various functions.

[0035] In this specification, the functions of the source and drain of a transistor may be interchanged when transistors of different polarities are used or when the direction of current flow changes during circuit operation, etc. Therefore, in this specification, the terms source and drain may be used interchangeably.

[0036] In this specification, a numerical range expressed using "to" means a range that includes the numerical value written before "to" as the lower limit and the numerical value written after "to" as the upper limit.

[0037] The present inventors have invented the present invention based on the following findings: By examining the atomic composition ratio of Ga (gallium) and Al (aluminum) in a sintered body of an oxide containing In (indium), Ga (gallium), and Al (aluminum), the present inventors have discovered that stable sputtering is possible even when a large panel is manufactured using a large-scale device, and that TFTs with excellent processability, high mobility, and excellent in-plane uniformity of optical reliability can be obtained.

[0038] Furthermore, the present inventors have investigated the atomic composition ratio of Ga (gallium) and Al (aluminum) in a sintered body of an oxide containing In (indium), Ga (gallium), and Al (aluminum), and have also investigated reducing the amount of pores generated in the sintered body. Through these investigations, they have discovered that even when a large panel is manufactured using a large-scale device, stable sputtering is possible with the occurrence of target cracking suppressed, and that TFTs with excellent processability, high mobility, and excellent in-plane uniformity of optical reliability can be obtained.

[0039] 1. Sintered Body The sintered body according to this embodiment will be described by taking the first and second aspects as examples.

[0040] [First Aspect] A first aspect of the sintered body according to this embodiment is a sintered body of an oxide containing In (indium), Ga (gallium), and Al (aluminum), in which the atomic composition ratios of the In element and the Al element satisfy the following formulas (1) and (2): [In] / ([In]+[Ga]+[Al])>0.70 (1) [Al] / ([In]+[Ga]+[Al])>0.01 (2)

[0041] In this specification, in the formulas expressing atomic ratios, [In], [Ga], and [Al] represent the numbers of indium atoms, gallium atoms, and aluminum atoms in the sintered body, respectively.

[0042] The sintered body according to this embodiment, in both the first aspect and the second aspect described below, may consist essentially of only In (indium), Ga (gallium), Al (aluminum), and O (oxygen). Here, "substantially" means that the sintered body according to this embodiment may contain other components as long as the effects of the present invention resulting from the combination of In, Ga, Al, and O are achieved. In this case, the sintered body according to this embodiment, in both the first aspect and the second aspect described below, may contain impurity elements. For example, in both the first aspect and the second aspect described below, 99 atomic % or more of the elements contained in the oxide sintered body may be In, Ga, Al, and O, or 99.9 atomic % or more of the elements contained in the oxide sintered body may be In, Ga, Al, and O. In both the first embodiment and the second embodiment described later, 99 atomic % or more of the metal elements contained in the oxide sintered body may be In, Ga, and Al, or 99.9 atomic % or more of the metal elements contained in the oxide sintered body may be In, Ga, and Al. In this specification, atomic % may be expressed as at %.

[0043] Impurities refer to elements that are not intentionally added but are mixed in at least one of the raw materials and the manufacturing process. That is, impurities are inevitable impurities that are inevitably included. The same applies to the following explanation. Examples of impurities include at least one element selected from the group consisting of alkali metal elements (elements such as Li (lithium), Na (sodium), K (potassium), and Rb (rubidium)), alkaline earth metal elements (elements such as Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium)), H (hydrogen), B (boron), C (carbon), N (nitrogen), F (fluorine), Si (silicon), and Cl (chlorine).

[0044] In the first aspect of the sintered body according to this embodiment, the atomic composition ratio of the Al element is equal to or greater than the lower limit of the above formula (2), and therefore the TFT obtained by sputtering using a target having the same atomic composition as the sintered body has excellent processability, and a TFT having high mobility and excellent in-plane uniformity of optical reliability can be obtained.

[0045] In the sintered body according to this embodiment, [Al] / ([In] + [Ga] + [Al]) is preferably greater than 0.01, more preferably 0.011 or greater, even more preferably 0.015 or greater, even more preferably 0.02 or greater, and even more preferably 0.025 or greater, from the viewpoint of obtaining a TFT having excellent processability, high mobility, and excellent in-plane uniformity of optical reliability. Increasing the atomic ratio of Al increases the optical band gap, making it difficult for electron-hole pairs to be generated during light irradiation, thereby improving optical reliability. There is no particular upper limit to [Al] / ([In] + [Ga] + [Al]). For example, [Al] / ([In] + [Ga] + [Al]) is preferably less than 0.18, more preferably 0.15 or less, even more preferably 0.09 or less, and even more preferably 0.08 or less, from the viewpoint of obtaining a TFT having excellent processability, high mobility, and excellent in-plane uniformity of optical reliability. If the atomic ratio of Al element is too high, the Al element in the oxide thin film contained in the TFT tends to become a scattering source in electron conduction, which tends to lead to a decrease in mobility.

[0046] In the sintered body according to this embodiment, [In] / ([In] + [Ga] + [Al]) is preferably 0.71 or more, more preferably 0.72 or more, from the viewpoint of obtaining a TFT having excellent processability, high mobility, and excellent in-plane uniformity of optical reliability. Increasing the atomic ratio of In makes it easier for the oxide semiconductor film (oxide thin film) to crystallize by annealing at the TFT production process temperature (250°C to 450°C), thereby achieving high mobility. The upper limit of [In] / ([In] + [Ga] + [Al]) is not particularly limited. For example, from the viewpoint of obtaining a TFT having excellent processability, high mobility, and excellent in-plane uniformity of optical reliability, [In] / ([In] + [Ga] + [Al]) is preferably less than 0.99, more preferably 0.98 or less, even more preferably 0.97 or less, and even more preferably 0.95 or less. By lowering the atomic ratio of In element within the above range, crystallization after film formation is suppressed, and it becomes easier to process uniformly without leaving any residue during patterning processing in the manufacture of TFTs.

[0047] In the sintered body according to this embodiment, the atomic composition ratio of Ga element (gallium element) is not particularly limited. From the viewpoint of obtaining a TFT with excellent processability, high mobility, and excellent in-plane uniformity of optical reliability, it is preferable to satisfy the following formula (3): 0.23≧[Ga] / ([In]+[Ga]+[Al])≧0.04 (3)

[0048] From the viewpoint of achieving excellent TFT processability and high mobility and in-plane uniformity of optical reliability, [Ga] / ([In] + [Ga] + [Al]) is preferably 0.05 or more, even more preferably 0.06 or more, even more preferably 0.07 or more, and even more preferably 0.08 or more. [Ga] / ([In] + [Ga] + [Al]) is also preferably 0.10 or more. Increasing the amount of Ga atoms suppresses crystallization after film formation, reduces residue during patterning processing during TFT fabrication, and facilitates uniform processing. [Ga] / ([In] + [Ga] + [Al]) is more preferably 0.225 or less, even more preferably 0.22 or less, and even more preferably 0.20 or less, from the viewpoint of achieving excellent TFT processability and high mobility and in-plane uniformity of optical reliability. It is also preferable that [Ga] / ([In] + [Ga] + [Al]) is 0.18 or less. Reducing the amount of Ga atoms results in a higher In ratio, which makes it easier for the oxide semiconductor film (oxide thin film) to crystallize by annealing at a TFT manufacturing process temperature (250°C to 450°C), thereby making it easier for high mobility to be achieved.

[0049] In the sintered body according to this embodiment, from the viewpoint of obtaining a TFT having excellent processability, high mobility, and excellent in-plane uniformity of optical reliability, it is preferable that the atomic composition ratio of Ga (gallium) element to Al (aluminum) element satisfies the following condition.

[0050] When the atomic composition ratio of the Ga element expressed by {[Ga] / ([In]+[Ga]+[Al])}×100 is x and the atomic composition ratio of the Al element expressed by {[Al] / ([In]+[Ga]+[Al])}×100 is y, it is preferable that the x and y are within the composition ranges surrounded by the straight lines of the following (A1), (B0), (C1), (D1), and (E1) in atomic %: x≧4 (A1) x≦22.5 (B0) y>1 (C1) 6x+14y−98≧0 (D1) 4x+20y−180≦0 (E1)

[0051] From the same viewpoint, the sintered body of the first embodiment more preferably falls within the composition range surrounded by the straight lines (A1), (B1), (C1), (D1), and (E1) below: x≧4 (A1) x≦22 (B1) y>1 (C1) 6x+14y−98≧0 (D1) 4x+20y−180≦0 (E1)

[0052] From the same viewpoint, it is more preferable that the sintered body of the first embodiment is within the composition range surrounded by the straight lines (A2), (B2), (C1), (D1), and (E1) below: x≧8 (A2) x≦20 (B2) y>1 (C1) 6x+14y−98≧0 (D1) 4x+20y−180≦0 (E1)

[0053] From the same viewpoint, it is further preferable that the sintered body of the first embodiment is within the composition range surrounded by the straight lines (A3), (B3), (C1), (D1), and (E1) below: x≧10 (A3) x≦18 (B3) y>1 (C1) 6x+14y−98≧0 (D1) 4x+20y−180≦0 (E1)

[0054] From the same viewpoint, the sintered body of the first embodiment is also preferably within any of the composition range surrounded by the straight lines connecting (A1), (C1), (D1), and (E1) with the following formula (B0-0), the composition range surrounded by the straight lines connecting (A1), (C1), (D1), and (E1) with the following formula (B0-1), and the composition range surrounded by the straight lines connecting (A1), (C1), (D1), and (E1) with the following formula (B0-2): x≦23 (B0-0) 22<x≦23 (B0-1) 22<x≦22.5 (B0-2)

[0055] When the atomic composition ratio of Ga element in the sintered body satisfies the above (A1), preferably the above (A2), crystallization after film formation is suppressed, and the sintered body can be easily processed uniformly without residue during patterning processing in TFT fabrication. When the atomic composition ratio of Ga element in the sintered body satisfies the above (B0), more preferably the above (B1), and even more preferably the above (B2), the atomic ratio of In element is increased, which makes it easier for the oxide semiconductor film (oxide thin film) to crystallize upon annealing at the TFT fabrication process temperature (250°C to 450°C), resulting in high mobility. When the atomic composition ratio of Al element in the sintered body satisfies the above (C1), the in-plane uniformity of the optical reliability of TFTs obtained using the sintered body according to this embodiment is excellent. When the atomic composition ratio of Ga element to Al element in the sintered body satisfies the above (D1), i.e., when the above (D1) is equal to 0 (zero) or is in a range greater than 0 (zero), the processability of the TFT obtained using the sintered body according to this embodiment is excellent. In other words, in the TFT obtained using the sintered body according to this embodiment, the inclusion of residue after patterning is suppressed. When the atomic composition ratio of Ga element to Al element in the sintered body satisfies the above (E1), i.e., when the above (E1) is equal to 0 (zero) or is in a range less than 0 (zero), the in-plane uniformity of the high mobility of the TFT obtained using the sintered body according to this embodiment is excellent.

[0056] The content (atomic ratio) of each metal element in the sintered body can be determined by measuring the amount of each element by ICP (Inductive Coupled Plasma) measurement or XRF (X-ray Fluorescence) measurement. An inductively coupled plasma optical emission spectrometer can be used for ICP measurement. A thin film X-ray fluorescence analyzer can be used for XRF measurement.

[0057] 1 and 2, as shown in FIG. 1, the atomic composition ratio of Ga (gallium) element to Al (aluminum) element is preferably in the range surrounded by line A1, line B0, line C1, line D1, and line E1, and more preferably in the range surrounded by line A1, line B1, line C1, line D1, and line E1, and as shown in FIG. 2, the atomic composition ratio of Ga (gallium) element to Al (aluminum) element is even more preferably in the range surrounded by line A2, line B2, line C1, line D1, and line E1.

[0058] From the viewpoints of enabling stable sputtering in large-scale manufacturing equipment (large-scale equipment), and of making it easier to obtain TFTs with excellent processability for TFTs and high mobility and excellent in-plane uniformity of optical reliability, the sintered body preferably contains a bixbyite structure containing In element and a crystalline structure belonging to either the P1 or P-1 space group. A crystalline structure belonging to either the P1 or P-1 space group is a triclinic crystalline structure belonging to either the P1 or P-1 space group. A crystalline structure belonging to the P1 space group is represented by the following crystalline structure parameter (X), and a crystalline structure belonging to the P-1 space group is represented by the following crystalline structure parameter (Y). The fact that the sintered body contains a bixbyite structure containing In element and the crystalline structure belonging to either the P1 or P-1 space group can both be confirmed by X-ray diffraction of the sintered body.

[0059] Crystal structure parameters (X): the lattice constants are a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α = 111.70 ± 0.50°, β = 107.70 ± 0.50°, and γ = 90.00 ± 0.50°; the crystal system is triclinic; the metal in the atomic configuration below owned by the space group P1 is any one of In, Ga, and Al, or any two or more of In, Ga, and Al, sharing the same atomic coordinates at a certain ratio; the atomic coordinates at which the metal is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01; and the atomic coordinates at which oxygen is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01. Atomic type: Metal, atomic coordinates (x=0.04, y=0.36, z=0.87) Atomic type: Metal, atomic coordinates (x=0.13, y=0.12, z=0.62) Atomic type: Metal, atomic coordinates (x=0.21, y=0.85, z=0.39) Atomic type: Metal, atomic coordinates (x=0.23, y=0.11, z=0.97) Atomic type: Metal, atomic coordinates (x=0.29, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.46, y=0.12, z=0.63) Atomic species: Metal, atomic coordinates (x=0.58, y=0.14, z=0.01) Atomic species: Metal, atomic coordinates (x=0.62, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.69, y=0.18, z=0.32) Atomic type: Metal, atomic coordinates (x=0.09, y=0.88, z=0.03) Atomic type: Metal, atomic coordinates (x=0.02, y=0.13, z=0.30) Atomic type: Metal, atomic coordinates (x=0.06, y=0.61, z=0.46) Atomic type: Metal, atomic coordinates (x=0.15, y=0.40, z=0.19) Atomic type: Metal, atomic coordinates (x=0.26, y=0.36, z=0.54) Atomic type: Metal, atomic coordinates (x=0.34, y=0.13, z=0.30) Atomic type: Metal, atomic coordinates (x=0.41, y=0.61, z=0.45) Atomic type: Metal, atomic coordinates (x=0.48, y=0.40, z=0.23) Atomic type: Metal, atomic coordinates (x=0.84, y=0.39, z=0.23) Atomic type: Metal, atomic coordinates (x=0.96, y=0.64, z=0.13) Atomic species: Metal, atomic coordinates (x=0.87, y=0.88, z=0.38) Atomic species: Metal, atomic coordinates (x=0.79, y=0.15, z=0.61) Atomic species: Metal, atomic coordinates (x=0.77, y=0.89, z=0.03) Atomic type: Metal, atomic coordinates (x=0.71, y=0.36, z=0.89) Atomic type: Metal, atomic coordinates (x=0.54, y=0.88, z=0.37) Atomic type: Metal, atomic coordinates (x=0.42, y=0.86, z=0.99) Atomic type: Metal, atomic coordinates (x=0.38, y=0.36, z=0.89) Atomic type: Metal, atomic coordinates (x=0.31, y=0.82, z=0.68) Atomic type: Metal, atomic coordinates (x=0.91, y=0.12, z=0.97) Atomic type: Metal, atomic coordinates (x=0.98, y=0.87, z=0.70) Atomic type: Metal, atomic coordinates (x=0.94, y=0.39, z=0.54) Atomic type: Metal, atomic coordinates (x=0.85, y=0.60, z=0.81) Atomic type: Metal, atomic coordinates (x=0.74, y=0.64, z=0.46) Atomic type: Metal, atomic coordinates (x=0.66, y=0.87, z=0.70) Atomic type: Metal, atomic coordinates (x=0.59, y=0.39, z=0.55) Atomic type: Metal, atomic coordinates (x=0.52, y=0.60, z=0.77) Atomic species: Metal, atomic coordinates (x = 0.16, y = 0.61, z = 0.77) Atomic species: Oxygen, atomic coordinates (x = 0.02, y = 0.73, z = 0.36) Atomic species: Oxygen, atomic coordinates (x = 0.03, y = 0.45, z = 0.29) Atomic species: Oxygen, atomic coordinates (x = 0.05, y = 0.02, z = 0.40) Atomic species: Oxygen, atomic coordinates (x = 0.10, y = 0.74, z = 0.65) Atomic species: Oxygen, atomic coordinates (x = 0.10, y = 0.23, z = 0.06) Atomic species: Oxygen, atomic coordinates (x = 0.12, y = 0.51, z = 0.09) Atomic species: Oxygen, atomic coordinates (x = 0.12, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.13, y = 0.79, z = 0.17) Atomic species: oxygen, atomic coordinates (x = 0.19, y = 0.21, z = 0.84) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.23, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.25, y = 0.66, z = 0.49) Atomic species: oxygen, atomic coordinates (x = 0.27, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.30, y = 0.26, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.33, y = 0.44, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.39, y = 0.73, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.41, y = 0.24, z = 0.07) Atomic species: oxygen, atomic coordinates (x = 0.43, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.46, y = 0.51, z = 0.11) Atomic species: oxygen, atomic coordinates (x = 0.47, y = 0.79, z = 0.15) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.25, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.64, y = 0.03, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.66, y = 0.34, z = 0.23) Atomic species: oxygen, atomic coordinates (x = 0.72, y = 0.03, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.78, y = 0.51, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.25, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.96, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.98, y = 0.27, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.97, y = 0.55, z = 0.72) Atomic species: oxygen, atomic coordinates (x = 0.95, y = 0.98, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.90, y = 0.26, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.90, y = 0.77, z = 0.94) Atomic species: oxygen, atomic coordinates (x = 0.88, y = 0.49, z = 0.91) Atomic species: oxygen, atomic coordinates (x = 0.88, y = 0.53, z = 0.43) Atomic species: oxygen, atomic coordinates (x = 0.87, y = 0.21, z = 0.83) Atomic species: oxygen, atomic coordinates (x = 0.81, y = 0.79, z = 0.16) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.77, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.75, y = 0.34, z = 0.51) Atomic species: oxygen, atomic coordinates (x = 0.73, y = 0.98, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.70, y = 0.74, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.67, y = 0.56, z = 0.71) Atomic species: oxygen, atomic coordinates (x = 0.62, y = 0.98, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.61, y = 0.27, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.59, y = 0.76, z = 0.93) Atomic species: oxygen, atomic coordinates (x = 0.58, y = 0.53, z = 0.43) Atomic species: oxygen, atomic coordinates (x = 0.54, y = 0.49, z = 0.89) Atomic species: oxygen, atomic coordinates (x = 0.53, y = 0.21, z = 0.85) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.75, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.36, y = 0.97, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.34, y = 0.66, z = 0.77) Atomic species: oxygen, atomic coordinates (x = 0.28, y = 0.97, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.22, y = 0.49, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.75, z = 0.94) Atomic species: oxygen, atomic coordinates (x = 0.04, y = 0.98, z = 0.88).

[0060] Crystal structure parameters (Y): the lattice constants are a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α = 111.70 ± 0.50°, β = 107.70 ± 0.50°, and γ = 90.00 ± 0.50°; the crystal system is triclinic; the metals in the atomic arrangement below owned by the space group P-1 are in a state where any one of In, Ga, and Al, or any two or more of In, Ga, and Al, share the same atomic coordinates in a certain ratio; the atomic coordinates where the metals are arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01; and the atomic coordinates where oxygen is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01. Atomic type: Metal, atomic coordinates (x=0.04, y=0.36, z=0.87) Atomic type: Metal, atomic coordinates (x=0.13, y=0.12, z=0.62) Atomic type: Metal, atomic coordinates (x=0.21, y=0.85, z=0.39) Atomic type: Metal, atomic coordinates (x=0.23, y=0.11, z=0.97) Atomic type: Metal, atomic coordinates (x=0.29, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.46, y=0.12, z=0.63) Atomic species: Metal, atomic coordinates (x=0.58, y=0.14, z=0.01) Atomic species: Metal, atomic coordinates (x=0.62, y=0.64, z=0.11) Atomic type: Metal, atomic coordinates (x=0.69, y=0.18, z=0.32) Atomic type: Metal, atomic coordinates (x=0.09, y=0.88, z=0.03) Atomic type: Metal, atomic coordinates (x=0.02, y=0.13, z=0.30) Atomic type: Metal, atomic coordinates (x=0.06, y=0.61, z=0.46) Atomic type: Metal, atomic coordinates (x=0.15, y=0.40, z=0.19) Atomic type: Metal, atomic coordinates (x=0.26, y=0.36, z=0.54) Atomic type: Metal, atomic coordinates (x=0.34, y=0.13, z=0.30) Atomic type: Metal, atomic coordinates (x=0.41, y=0.61, z=0.45) Atomic species: Metal, atomic coordinates (x = 0.48, y = 0.40, z = 0.23) Atomic species: Metal, atomic coordinates (x = 0.84, y = 0.39, z = 0.23) Atomic species: Oxygen, atomic coordinates (x = 0.02, y = 0.73, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.03, y = 0.45, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.05, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.74, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.23, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.51, z = 0.09) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.13, y = 0.79, z = 0.17) Atomic species: oxygen, atomic coordinates (x = 0.19, y = 0.21, z = 0.84) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.23, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.25, y = 0.66, z = 0.49) Atomic species: oxygen, atomic coordinates (x = 0.27, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.30, y = 0.26, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.33, y = 0.44, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.39, y = 0.73, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.41, y = 0.24, z = 0.07) Atomic species: oxygen, atomic coordinates (x = 0.43, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.46, y = 0.51, z = 0.11) Atomic species: oxygen, atomic coordinates (x = 0.47, y = 0.79, z = 0.15) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.25, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.64, y = 0.03, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.66, y = 0.34, z = 0.23) Atomic species: oxygen, atomic coordinates (x = 0.72, y = 0.03, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.78, y = 0.51, z = 0.12) Atomic species: Oxygen, atomic coordinates (x = 0.80, y = 0.25, z = 0.06). Atomic species: Oxygen, atomic coordinates (x = 0.96, y = 0.02, z = 0.12).

[0061] When the crystal structure belonging to the space group P1 is included, the crystal structure belonging to the space group P1 may be a crystal structure represented by the following crystal structure parameter (X1).

[0062] Crystal structure parameters (X1): The lattice constants are a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α = 111.70 ± 0.50°, β = 107.70 ± 0.50°, and γ = 90.00 ± 0.50°; the crystal system is triclinic; the metal in the atomic configuration below owned by the space group P1 is any one of In, Ga, and Al, or any two or more of In, Ga, and Al, sharing the same atomic coordinates at a certain ratio; the atomic coordinates at which the metal is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01; and the atomic coordinates at which oxygen is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01. Atomic species: Metal, atomic coordinates (x=0.04478, y=0.36228, z=0.86934) Atomic species: Metal, atomic coordinates (x=0.12677, y=0.11682, z=0.62279) Atomic species: Metal, atomic coordinates (x=0.21268, y=0.8504, z=0.38665) Atomic species: Metal, atomic coordinates (x=0.23283, y=0.11047, z=0.97132) Atomic species: Metal, atomic coordinates (x=0.28695, y=0.64349, z=0.10627) Atomic species: Metal, atomic coordinates (x=0.45663, y=0.11849, z=0.62655) Atomic species: Metal, atomic coordinates (x=0.58343, y=0.14455, z=0.0065) Atomic species: Metal, atomic coordinates (x=0.62181, y=0.6417, z=0.10725) Atomic species: Metal, atomic coordinates (x=0.68785, y=0.18413, z=0.31614) Atomic species: Metal, atomic coordinates (x=0.08662, y=0.88097, z=0.03282) Atomic species: Metal, atomic coordinates (x=0.02388, y=0.13328, z=0.30129) Atomic species: Metal, atomic coordinates (x=0.0627, y=0.6051, z=0.4561) Atomic type: Metal, atomic coordinates (x=0.1503, y=0.3962, z=0.1949) Atomic type: Metal, atomic coordinates (x=0.2624, y=0.36429, z=0.5374) Atomic type: Metal, atomic coordinates (x=0.34051, y=0.1304, z=0.29845) Atomic species: metal, atomic coordinates (x=0.4081, y=0.6082, z=0.4509) Atomic type: Metal, atomic coordinates (x=0.4821, y=0.39651, z=0.22899) Atomic type: Metal, atomic coordinates (x=0.8369, y=0.39245, z=0.23049) Atomic species: Metal, atomic coordinates (x=0.95522, y=0.63772, z=0.13066) Atomic species: Metal, atomic coordinates (x=0.87323, y=0.88318, z=0.37721) Atomic species: metal, atomic coordinates (x=0.78732, y=0.1496, z=0.61335) Atomic species: Metal, atomic coordinates (x=0.76717, y=0.88953, z=0.02868) Atomic species: Metal, atomic coordinates (x=0.71305, y=0.35651, z=0.89373) Atomic species: Metal, atomic coordinates (x=0.54337, y=0.88151, z=0.37345) Atomic species: Metal, atomic coordinates (x=0.41657, y=0.85545, z=0.9935) Atomic species: Metal, atomic coordinates (x=0.37819, y=0.3583, z=0.89275) Atomic species: Metal, atomic coordinates (x=0.31215, y=0.81587, z=0.68386) Atomic species: Metal, atomic coordinates (x=0.91338, y=0.11903, z=0.96718) Atomic species: Metal, atomic coordinates (x=0.97612, y=0.86672, z=0.69871) Atomic type: Metal, atomic coordinates (x=0.9373, y=0.3949, z=0.5439) Atomic type: Metal, atomic coordinates (x=0.8497, y=0.6038, z=0.8051) Atomic type: Metal, atomic coordinates (x=0.7376, y=0.63571, z=0.4626) Atomic species: metal, atomic coordinates (x=0.65949, y=0.8696, z=0.70155) Atomic species: Metal, atomic coordinates (x = 0.5919, y = 0.3918, z = 0.5491) Atomic species: Metal, atomic coordinates (x = 0.5179, y = 0.60349, z = 0.77101) Atomic species: Metal, atomic coordinates (x = 0.1631, y = 0.60755, z = 0.76951) Atomic species: Oxygen, atomic coordinates (x = 0.0157, y = 0.7332, z = 0.3627) Atomic species: Oxygen, atomic coordinates (x = 0.0295, y = 0.4499, z = 0.285) Atomic species: Oxygen, atomic coordinates (x = 0.0518, y = 0.0204, z = 0.4013) Atomic species: Oxygen, atomic coordinates (x = 0.Atomic species: Oxygen, atomic coordinates (x = 0.0975, y = 0.7442, z = 0.6484) Atomic species: Oxygen, atomic coordinates (x = 0.1004, y = 0.231, z = 0.0611) Atomic species: Oxygen, atomic coordinates (x = 0.121, y = 0.5054, z = 0.0929) Atomic species: Oxygen, atomic coordinates (x = 0.1218, y = 0.4677, z = 0.5675) Atomic species: Oxygen, atomic coordinates (x = 0.1323, y = 0.7893, z = 0.17) Atomic species: Oxygen, atomic coordinates (x = 0.1917, y = 0.2052, z = 0.837) Atomic species: Oxygen, atomic coordinates (x = 0.1998, y = 0.2293, z = 0.3578) Atomic species: oxygen, atomic coordinates (x = 0.2461, y = 0.6607, z = 0.4873) Atomic species: oxygen, atomic coordinates (x = 0.2703, y = 0.0197, z = 0.1161) Atomic species: oxygen, atomic coordinates (x = 0.2975, y = 0.2578, z = 0.6451) Atomic species: oxygen, atomic coordinates (x = 0.3274, y = 0.4429, z = 0.2908) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.017, z = 0.3996) Atomic species: oxygen, atomic coordinates (x = 0.3852, y = 0.7303, z = 0.3495) Atomic species: oxygen, atomic coordinates (x = 0.4077, y = 0.2385, z = 0.0657) Atomic species: oxygen, atomic coordinates (x = 0.425, y = 0.4654, z = 0.5745) Atomic species: oxygen, atomic coordinates (x = 0.4569, y = 0.5063, z = 0.1142) Atomic species: oxygen, atomic coordinates (x = 0.472, y = 0.7862, z = 0.1502) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.2483, z = 0.3581) Atomic species: oxygen, atomic coordinates (x = 0.6404, y = 0.0285, z = 0.122) Atomic species: oxygen, atomic coordinates (x = 0.6587, y = 0.3356, z = 0.2257) Atomic species: oxygen, atomic coordinates (x = 0.7171, y = 0.0302, z = 0.3985) Atomic species: oxygen, atomic coordinates (x = 0.7808, y = 0.5096, z = 0.1234) Atomic species: oxygen, atomic coordinates (x = 0.8007, y = 0.2465, z = 0.0562) Atomic species: oxygen, atomic coordinates (x = 0.9644, y = 0.0248, z = 0.117) Atomic species: oxygen, atomic coordinates (x = 0.9843, y = 0.2668, z = 0.6373) Atomic species: oxygen, atomic coordinates (x = 0.9705, y = 0.Atomic species: Oxygen, atomic coordinates (x = 0.5501, z = 0.715) Atomic species: Oxygen, atomic coordinates (x = 0.9482, y = 0.9796, z = 0.5987) Atomic species: Oxygen, atomic coordinates (x = 0.9025, y = 0.2558, z = 0.3516) Atomic species: Oxygen, atomic coordinates (x = 0.8996, y = 0.769, z = 0.9389) Atomic species: Oxygen, atomic coordinates (x = 0.879, y = 0.4946, z = 0.9071) Atomic species: Oxygen, atomic coordinates (x = 0.8782, y = 0.5323, z = 0.4325) Atomic species: Oxygen, atomic coordinates (x = 0.8677, y = 0.2107, z = 0.83) Atomic species: oxygen, atomic coordinates (x = 0.8083, y = 0.7948, z = 0.163) Atomic species: oxygen, atomic coordinates (x = 0.8002, y = 0.7707, z = 0.6422) Atomic species: oxygen, atomic coordinates (x = 0.7539, y = 0.3393, z = 0.5127) Atomic species: oxygen, atomic coordinates (x = 0.7297, y = 0.9803, z = 0.8839) Atomic species: oxygen, atomic coordinates (x = 0.7025, y = 0.7422, z = 0.3549) Atomic species: oxygen, atomic coordinates (x = 0.6726, y = 0.5571, z = 0.7092) Atomic species: oxygen, atomic coordinates (x = 0.62, y = 0.983, z = 0.6004) Atomic species: oxygen, atomic coordinates (x = 0.6148, y = 0.2697, z = 0.6505) Atomic species: oxygen, atomic coordinates (x = 0.5923, y = 0.7615, z = 0.9343) Atomic species: oxygen, atomic coordinates (x = 0.575, y = 0.5346, z = 0.4255) Atomic species: oxygen, atomic coordinates (x = 0.5431, y = 0.4937, z = 0.8858) Atomic species: oxygen, atomic coordinates (x = 0.528, y = 0.2138, z = 0.8498) Atomic species: oxygen, atomic coordinates (x = 0.5, y = 0.7517, z = 0.6419) Atomic species: Oxygen, atomic coordinates (x = 0.3596, y = 0.9715, z = 0.878) Atomic species: Oxygen, atomic coordinates (x = 0.3413, y = 0.6644, z = 0.7743) Atomic species: Oxygen, atomic coordinates (x = 0.2829, y = 0.9698, z = 0.6015) Atomic species: Oxygen, atomic coordinates (x = 0.2192, y = 0.4904, z = 0.8766) Atomic species: Oxygen, atomic coordinates (x = 0.1993, y = 0.7535, z = 0.9438) Atomic species: Oxygen, atomic coordinates (x = 0.0356, y = 0.9752, z = 0.883).

[0063] When the crystal structure belonging to the space group P-1 is included, the crystal structure belonging to the space group P-1 may be a crystal structure represented by the following crystal structure parameter (Y1). Crystal structure parameters (Y1): the lattice constants are a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α = 111.70 ± 0.50°, β = 107.70 ± 0.50°, and γ = 90.00 ± 0.50°; the crystal system is triclinic; the metal in the atomic configuration below owned by the space group P-1 is any one of In, Ga, and Al, or any two or more of In, Ga, and Al, sharing the same atomic coordinates at a certain ratio; the atomic coordinates at which the metal is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01; and the atomic coordinates at which oxygen is arranged include the range of x ± 0.01, y ± 0.01, z ± 0.01. Atomic species: Metal, atomic coordinates (x=0.04478, y=0.36228, z=0.86934) Atomic species: Metal, atomic coordinates (x=0.12677, y=0.11682, z=0.62279) Atomic species: Metal, atomic coordinates (x=0.21268, y=0.8504, z=0.38665) Atomic species: Metal, atomic coordinates (x=0.23283, y=0.11047, z=0.97132) Atomic species: Metal, atomic coordinates (x=0.28695, y=0.64349, z=0.10627) Atomic species: Metal, atomic coordinates (x=0.45663, y=0.11849, z=0.62655) Atomic species: Metal, atomic coordinates (x=0.58343, y=0.14455, z=0.0065) Atomic species: Metal, atomic coordinates (x=0.62181, y=0.6417, z=0.10725) Atomic species: Metal, atomic coordinates (x=0.68785, y=0.18413, z=0.31614) Atomic species: Metal, atomic coordinates (x=0.08662, y=0.88097, z=0.03282) Atomic species: Metal, atomic coordinates (x=0.02388, y=0.13328, z=0.30129) Atomic species: Metal, atomic coordinates (x=0.0627, y=0.6051, z=0.4561) Atomic type: Metal, atomic coordinates (x=0.1503, y=0.3962, z=0.1949) Atomic type: Metal, atomic coordinates (x=0.2624, y=0.Atomic species: Metal, atomic coordinates (x = 0.36429, z = 0.5374) Atomic species: Metal, atomic coordinates (x = 0.34051, y = 0.1304, z = 0.29845) Atomic species: Metal, atomic coordinates (x = 0.4081, y = 0.6082, z = 0.4509) Atomic species: Metal, atomic coordinates (x = 0.4821, y = 0.39651, z = 0.22899) Atomic species: Metal, atomic coordinates (x = 0.8369, y = 0.39245, z = 0.23049) Atomic species: Oxygen, atomic coordinates (x = 0.0157, y = 0.7332, z = 0.3627) Atomic species: Oxygen, atomic coordinates (x = 0.0295, y = 0.4499, z = 0.285) Atomic species: oxygen, atomic coordinates (x = 0.0518, y = 0.0204, z = 0.4013) Atomic species: oxygen, atomic coordinates (x = 0.0975, y = 0.7442, z = 0.6484) Atomic species: oxygen, atomic coordinates (x = 0.1004, y = 0.231, z = 0.0611) Atomic species: oxygen, atomic coordinates (x = 0.121, y = 0.5054, z = 0.0929) Atomic species: oxygen, atomic coordinates (x = 0.1218, y = 0.4677, z = 0.5675) Atomic species: oxygen, atomic coordinates (x = 0.1323, y = 0.7893, z = 0.17) Atomic species: oxygen, atomic coordinates (x = 0.1917, y = 0.2052, z = 0.837) Atomic species: oxygen, atomic coordinates (x = 0.1998, y = 0.2293, z = 0.3578) Atomic species: oxygen, atomic coordinates (x = 0.2461, y = 0.6607, z = 0.4873) Atomic species: oxygen, atomic coordinates (x = 0.2703, y = 0.0197, z = 0.1161) Atomic species: oxygen, atomic coordinates (x = 0.2975, y = 0.2578, z = 0.6451) Atomic species: oxygen, atomic coordinates (x = 0.3274, y = 0.4429, z = 0.2908) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.017, z = 0.3996) Atomic species: oxygen, atomic coordinates (x = 0.3852, y = 0.7303, z = 0.3495) Atomic species: oxygen, atomic coordinates (x = 0.4077, y = 0.2385, z = 0.0657) Atomic species: oxygen, atomic coordinates (x = 0.425, y = 0.4654, z = 0.5745) Atomic species: oxygen, atomic coordinates (x = 0.4569, y = 0.5063, z = 0.1142) Atomic species: oxygen, atomic coordinates (x = 0.472, y = 0.7862, z = 0.1502) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.Atomic species: Oxygen, atomic coordinates (x = 0.6404, y = 0.0285, z = 0.122). Atomic species: Oxygen, atomic coordinates (x = 0.6587, y = 0.3356, z = 0.2257). Atomic species: Oxygen, atomic coordinates (x = 0.7171, y = 0.0302, z = 0.3985). Atomic species: Oxygen, atomic coordinates (x = 0.7808, y = 0.5096, z = 0.1234). Atomic species: Oxygen, atomic coordinates (x = 0.8007, y = 0.2465, z = 0.0562). Atomic species: Oxygen, atomic coordinates (x = 0.9644, y = 0.0248, z = 0.117).

[0064] The bixbyite structure containing In element is preferably a bixbyite structure of substantially indium oxide. Here, "substantially" means that 90% by volume or more, preferably 95% by volume or more, and more preferably 98% by volume or more of the crystal structure of the bixbyite structure is indium oxide exhibiting the bixbyite structure. The bixbyite structure containing In element is preferably In ２ O ３ The bixbyite structure referred to here is an In structure in which at least one of Ga and Al may be substituted at the In site, and the lattice constant is In, which is composed only of In and O. ２ O ３ It may be a different value.

[0065] The crystal structure belonging to either the P1 or P-1 space group may be either a crystal structure belonging to the P1 space group or a crystal structure belonging to the P-1 space group. The crystal structure belonging to either the P1 or P-1 space group is preferably a crystal structure belonging to the P-1 space group. Note that the "-" between the "P" and "1" in the space group "P-1" (P1 bar) is originally written above the "1" (the same applies hereinafter to the notation of other space groups).

[0066] In the sintered body according to this embodiment, the weight ratio of the bixbyite structure containing In element to the crystal of the entire sintered body is preferably 70% or more, from the viewpoint of providing excellent TFT processability and making it easier to obtain TFTs with high mobility and excellent in-plane uniformity of optical reliability. The weight ratio of the bixbyite structure containing In element to the crystal of the entire sintered body is determined by performing Rietveld analysis on the spectrum obtained by performing X-ray diffraction measurement on the sintered body to calculate the weight ratio of the bixbyite structure containing In element, the crystal structure belonging to either the P1 or P-1 space group, and other crystal structures. The weight ratio of the bixbyite structure containing In element to the crystal of the entire sintered body is preferably 99% or less. The bixbyite structure containing In element and the crystal structure belonging to either the P1 or P-1 space group can be confirmed by X-ray diffraction (XRD) measurement.

[0067] The sintered body according to this embodiment may contain H element (hydrogen element). When the sintered body contains H element, the atomic concentration of H element in the sintered body is 1×10 １６ cm －３ That's it, 1 x 10 １８ cm －３ The atomic concentration of H element in the sintered body is preferably less than 3×10 １６ cm －３ More preferably, it is 5×10 or more. １６ cm －３ If the atomic concentration of H element in the sintered body is too low, the influence of H element degassed from the adhesion prevention plate of the sputtering chamber during film formation is large, and the degassed H element is mixed non-uniformly into the formed film, which may lead to a decrease in the in-plane uniformity of the TFT characteristics. The atomic concentration of H element in the sintered body is 5×10 １７ cm －３ More preferably, it is 3×10 or less. １７ cm －３If the atomic concentration of H element in the sintered body is too high, a large amount of H element will be mixed into the formed film, which may form a donor level or an acceptor level, which may result in a significant deterioration in the optical reliability of the TFT.

[0068] The sintered body according to this embodiment may contain C element (carbon element). When the sintered body contains C element, the lower limit of the atomic concentration of C element in the sintered body is not particularly limited. However, the amount of impurities at the time of manufacturing the target is preferably 1×10 １６ cm －３ When the sintered body contains the C element, the atomic concentration of the C element is 1×10 １６ cm －３ That's it, 1 x 10 １８ cm －３ The atomic concentration of the C element in the sintered body is preferably less than 7×10 １７ cm －３ More preferably, it is 4×10 or less. １７ cm －３ If the atomic concentration of the C element is too high, a large amount of C element is mixed into the formed film, which forms a donor level or an acceptor level, which may result in a significant deterioration in the optical reliability of the TFT.

[0069] The sintered body according to this embodiment may contain H element (hydrogen element) and C element (carbon element). When the sintered body contains both H element and C element, the atomic concentrations of both H element and C element are 1×10 １６ cm －３ That's it, 1 x 10 １８ cm －３ In this specification and the like, the unit of atomic concentration of H element and C element [atoms / cm ３ ] is [cm －３ ] may be written.

[0070] The atomic concentrations of H and C contained in the sintered body can be determined by secondary ion mass spectrometry (SIMS). A dynamic SIMS device can be used for the SIMS measurement.

[0071] The sintered body according to this embodiment preferably has a flexural strength of 190 MPa or more. The flexural strength of the sintered body is more preferably 200 MPa or more, and even more preferably 230 MPa or more. The upper limit of the flexural strength of the sintered body is not particularly limited. If the flexural strength of the sintered body is 190 MPa or more, for example, even when a large panel with a large area is produced using a large-scale device, sputtering is facilitated with target cracking suppressed. The flexural strength of the sintered body is determined based on JIS R 1601:2008 by placing a rectangular columnar test piece on two supports spaced 30 mm apart, applying a load to the presser with a presser in contact with the center, and calculating the average load (three-point bending strength) of 30 test pieces at which the test piece breaks.

[0072] [Second Aspect] A second aspect of the sintered body according to this embodiment is a sintered body of an oxide containing In (indium), Ga (gallium), and Al (aluminum), wherein the atomic composition ratio of the In element and the Al element satisfies the following formulas (1) and (2), and when the sintered body is observed with a scanning electron microscope, the area ratio of pores to the area of ​​the field of view is 0.1% or less: [In] / ([In]+[Ga]+[Al])>0.70 (1) [Al] / ([In]+[Ga]+[Al])>0.01 (2)

[0073] In the second aspect of the sintered body according to this embodiment, as in the first aspect, if the atomic composition ratio of the Al element is equal to or greater than the lower limit of the above formula (2), the TFT obtained by sputtering using a target having the same atomic composition as the sintered body has excellent processability, and a TFT with high mobility and excellent in-plane uniformity of optical reliability can be obtained. Furthermore, in the second aspect of the sintered body according to this embodiment, if the pore area ratio is 0.1% or less, the flexural strength is improved, so that even when a large panel is manufactured using a large-scale device, sputtering can be performed with the occurrence of target cracks suppressed.

[0074] In the second aspect of the sintered body according to this embodiment, the pore area ratio is preferably less than 0.1%, more preferably 0.09% or less, even more preferably 0.07% or less, and even more preferably 0.04% or less. The lower limit of the pore area ratio is not particularly limited. The pore area ratio may be 0% or more, or 0.01% or more.

[0075] Pores are holes that occur at the grain boundaries of crystal grains, and are observed as black areas in secondary electron images when SEM images are analyzed. The area ratio of pores is calculated as X = (S1 / St) x 100, where X is the area ratio of pores, St is the area of ​​the field of view when observed with a scanning electron microscope, and S1 is the area of ​​the pores.

[0076] 3C and 3D, the SEM image of the sintered body of this embodiment shows almost no black grain boundary areas, indicating that the sintered body of this embodiment has a pore area ratio of less than 0.1%. On the other hand, with reference to FIGS. 3A and 3B, the SEM image of the sintered body of the comparative example shows black grain boundary areas.

[0077] In the second aspect of the sintered body according to this embodiment, preferred specific examples of the atomic composition ratio of In and Al are the same as those described for the sintered body of the first aspect. Also, preferred specific examples of the atomic composition ratio of Ga are the same as those for the sintered body of the first aspect.

[0078] In the second aspect of the sintered body according to the present embodiment, when the atomic composition ratio of the Ga element expressed by {[Ga] / ([In]+[Ga]+[Al])}×100 is defined as x, and the atomic composition ratio of the Al element expressed by {[Al] / ([In]+[Ga]+[Al])}×100 is defined as y, the x and y are the same as the preferred specific examples in the sintered body of the first aspect.

[0079] A second aspect of the sintered body according to this embodiment may include the bixbyite structure containing In element described in the first aspect and the crystal structure described in the first aspect, the space group of which belongs to either P1 or P-1. In this case, preferred specific examples of the area ratio of the bixbyite structure containing In element relative to the field of view when the sintered body is observed with a scanning electron microscope are the same as those for the sintered body of the first aspect. Preferred specific examples of the area ratio of the crystal structure belonging to either P1 or P-1 space group relative to the field of view when the sintered body is observed with a scanning electron microscope are the same as those for the sintered body of the first aspect.

[0080] In a second aspect of the sintered body according to this embodiment, the sintered body may contain an H element (hydrogen element). When the sintered body contains an H element, preferred specific examples of the atomic concentration of the H element are the same as those for the sintered body of the first aspect. In a second aspect of the sintered body according to this embodiment, the sintered body may contain a C element (carbon element). When the sintered body contains a C element, preferred specific examples of the atomic concentration of the C element are the same as those for the sintered body of the first aspect. The same applies to specific examples when the sintered body contains both an H element and a C element.

[0081] In the second aspect of the sintered body according to this embodiment, preferred specific examples of the bending strength of the sintered body are the same as those of the sintered body of the first aspect.

[0082] The sintered body according to this embodiment is a sintered body of an oxide containing In (indium), Ga (gallium), and Al (aluminum), and the atomic composition ratio of the In element and the Al element satisfies the above-mentioned formula (1) and formula (2), thereby generating a crystal structure whose space group belongs to P1 or P-1. Furthermore, by optimizing the manufacturing conditions of the target, pores that occur at the grain boundaries during crystal growth of bixbyite containing In element are filled with a crystal structure whose space group belongs to P1 or P-1, and the condition of keeping the pore area ratio to 0.1% or less can be satisfied. Furthermore, as a result, a sintered body having a flexural strength of 190 MPa or more can be realized.

[0083] [Method for Manufacturing Sintered Body] A method for manufacturing a sintered body according to this embodiment will be described. An example of a preferred method for manufacturing a sintered body according to this embodiment has the following steps. The method for manufacturing a sintered body of an oxide containing In, Ga, and Al includes the steps of: mixing and crushing indium oxide, gallium oxide, and aluminum oxide using a bead mill, granulating the mixture by a spray-drying method to obtain a granulated powder, and then classifying the granulated powder (hereinafter sometimes referred to as a granulated powder manufacturing step); molding the classified granulated powder to obtain a molded body (hereinafter sometimes referred to as a molding step); and sintering the molded body (hereinafter sometimes referred to as a sintering step), wherein the atomic composition ratios of In and Al in the sintered body satisfy the following formulas (1) and (2): [In] / ([In]+[Ga]+[Al])>0.70 (1) [Al] / ([In]+[Ga]+[Al])>0.01 (2)

[0084] According to a preferred method for producing the sintered body of this embodiment, it is possible to obtain a sintered body of the first aspect of the sintered body of this embodiment, as described above. Also, according to a preferred method for producing the sintered body of this embodiment, it is possible to obtain a sintered body of the second aspect of the sintered body of this embodiment, as described above.

[0085] The granulated powder production process is carried out using indium oxide (In ２ O ３ ), gallium oxide (Ga ２O ３ ) and aluminum oxide (Al ２ O ３ ) as raw materials to obtain a granulated powder. The indium oxide, gallium oxide, and aluminum oxide used as raw materials are preferably in powder form, for example. In the granulated powder preparation step, first, a raw material mixture containing indium oxide, gallium oxide, and aluminum oxide to be used as raw materials is prepared. Next, the raw material mixture is mixed and crushed using a bead mill. Next, the mixed and crushed raw material mixture is dried using a spray dryer to obtain a granulated powder. Next, the granulated powder is classified.

[0086] The indium oxide is not particularly limited, and commercially available indium oxide powder can be used. The indium oxide powder is preferably high-purity, for example, 4N (0.9999) or higher. The gallium oxide is not particularly limited, and commercially available gallium oxide powder can be used. The gallium oxide powder is preferably high-purity, for example, 4N (0.9999) or higher. The aluminum oxide is not particularly limited, and commercially available aluminum oxide powder can be used. The aluminum oxide powder is preferably high-purity, for example, 4N (0.9999) or higher.

[0087] The raw material mixture may contain, for example, a dispersant for deflocculating the aggregates and a thickener for adjusting the viscosity to a level suitable for granulation in a spray dryer. Examples of the dispersant include ammonia-neutralized acrylic acid / methacrylic acid copolymer, and examples of the thickener include polyvinyl alcohol.

[0088] In the granulated powder production process, a bead mill is used to mix and crush the raw material mixture. Specifically, a wet bead mill is preferably used as the bead mill. The mixing and crushing process time varies depending on the size of the wet bead mill and the amount of raw material mixture to be processed. The process time may be adjusted, for example, so that the particle size distribution of the raw material mixture is uniform, with particles all measuring 1 μm or less. Examples of crushing media (beads) used in bead mills include zirconia, alumina, quartz, silicon nitride, stainless steel, mullite, glass, and silicon carbide (SiC). Among these, solid particle zirconia balls (also referred to as zirconia beads) are preferred as the crushing media (beads). The particle size of the zirconia balls is preferably 0.1 mm or more and 2 mm or less, and more preferably 0.5 mm or more and 1.5 mm or less. By reducing the particle size of the beads during crushing, the particle size of the crushed raw material mixture can be reduced. On the other hand, if the particle size of the beads is too small, the crushing time becomes long, which increases the takt time during target production.

[0089] The raw material mixture after mixing and crushing may be granulated immediately or may be subjected to a calcination treatment before granulation. The calcination treatment is usually performed by firing the raw material mixture at 700° C. or higher and 900° C. or lower for 1 hour or longer and 5 hours or shorter.

[0090] The raw material mixture after mixing and crushing is rapidly dried and granulated by a spray drying method. Specifically, a spray dryer is used to granulate the raw material mixture after mixing and crushing. The specific drying conditions using a spray dryer are determined by various conditions such as the concentration of the raw material mixture to be dried, the hot air temperature used for drying, the rotation speed of the spray dryer, and the air volume. When carrying out the spray drying method, it is advisable to determine the optimal conditions in advance. There are no particular restrictions on the shape of the granulated powder obtained in the granulated powder production step, but a spherical shape is preferred.

[0091] When a raw material mixture that has not been subjected to a calcination treatment is granulated by a spray drying method, the raw material mixture obtained by mixing and crushing may be used as is to prepare the granulated powder. When a raw material mixture that has been subjected to a calcination treatment is granulated by a spray drying method, the raw material mixture that has been subjected to a calcination treatment may be crushed again and used as a raw material mixture. In the raw material mixture that has been subjected to a calcination treatment, particles are bonded to each other, so when a granulation treatment is performed, it is preferable to perform a pulverization treatment before the granulation treatment.

[0092] The granulated powder is classified. In the following description, the granulated powder before classification may be referred to as raw granulated powder. Examples of classification methods include sieving the granulated powder after granulation to select particles within a desired particle size range. The sieve used in this method is preferably a sieve with openings large enough to allow granulated powder of the desired particle size to pass through. The sieves used in this method preferably include a first sieve for selecting the raw granulated powder based on the lower limit of the particle size range and a second sieve for selecting the raw granulated powder based on the upper limit of the particle size range. When controlling the particle size of the granulated powder to within a range of, for example, 150 μm or less, the raw granulated powder within the range of 150 μm or less is selected using a sieve with openings large enough to allow raw granulated powder of 150 μm or less to pass through but not to allow raw granulated powder exceeding 150 μm to pass through. Furthermore, when the particle size of the granulated powder is controlled to, for example, a range of 25 μm or more and 150 μm or less, first, a sieve (first sieve) having openings large enough to allow raw granulated powder less than 25 μm to pass through but not allow raw granulated powder of 25 μm or more to pass through is used to select raw granulated powder having a particle size of 25 μm or more. Next, the raw granulated powder after this selection is sorted using a sieve (second sieve) having openings large enough to allow raw granulated powder of 150 μm or less to pass through but not allow raw granulated powder of more than 150 μm to pass through, to select raw granulated powder having a particle size of 25 μm or more and 150 μm or less. The second sieve may be used first, followed by the first sieve.

[0093] The molding step is a step of molding the granulated powder obtained in the granulated powder preparation step to obtain a molded body. Specifically, the molding step is a step of filling a mold with the granulated powder obtained in the granulated powder preparation step, and molding the raw material powder filled in the mold to obtain a molded body.

[0094] Examples of the molding method in the molding step include die press molding. In order to obtain a sintered body with high sintering density as a sputtering target, it is preferable to preform the material by die press molding or the like in the molding step, and then further consolidate the material by cold isostatic pressing (CIP) or the like.

[0095] The sintering step is a step of sintering the compact obtained in the molding step to obtain a sintered body. In the sintering step, a commonly used sintering method such as atmospheric sintering, hot press sintering, or hot isostatic pressing (HIP) sintering can be used.

[0096] In the sintering process, after placing the molded body in a sintering furnace, it is preferable to first increase the temperature to 120°C to 200°C at a rate of 0.1°C / min to 1.0°C / min, and hold the temperature for 1 hour to 5 hours (first sintering condition). The first sintering condition allows, for example, degreasing of moisture and molding aids in the molded body. Next, it is preferable to increase the temperature to 300°C to 400°C at a rate of 0.1°C / min to 1.0°C / min, and hold the temperature for 1 hour to 5 hours (second sintering condition). Next, it is preferable to increase the temperature to 1300°C to 1400°C at a rate of 0.5°C / min to 2°C / min, and hold the temperature for 10 hours to 30 hours (third sintering condition).

[0097] The sintering atmosphere may be, for example, air or oxygen gas, a mixture of air or oxygen gas and a reducing gas, or a mixture of air or oxygen gas and an inert gas. Examples of the reducing gas include hydrogen gas, methane gas, and carbon monoxide gas. Examples of the inert gas include argon gas and nitrogen gas.

[0098] 2. Sputtering Target The sputtering target according to this embodiment is a sputtering target using the sintered body according to this embodiment (either the sintered body of the first aspect or the sintered body of the second aspect). The sputtering target according to this embodiment is obtained by using the sintered body according to this embodiment. That is, the sputtering target according to this embodiment includes the sintered body according to this embodiment. The sintered body according to this embodiment is used as a film raw material when forming a film by sputtering.

[0099] The sputtering target includes an oxide sintered body and a cooling and holding member such as a backing plate that is provided on the oxide sintered body as needed.

[0100] The shape of the sputtering target is not particularly limited. The sputtering target may be, for example, a plate-like shape as shown by reference numeral 1 in FIG. 4A or a cylindrical shape as shown by reference numeral 1A in FIG. 4B. In the case of a plate-like shape, the planar shape may be a rectangle as shown by reference numeral 1 in FIG. 4A or a circle as shown by reference numeral 1B in FIG. 4C. The oxide sintered body may be integrally molded, or may be a multi-piece type in which a plurality of divided oxide sintered bodies (reference numeral 1C) are each fixed to a backing plate 3 as shown in FIG. 4D. The backing plate is a member for holding and cooling the oxide sintered body. The material is preferably a material with excellent thermal conductivity, such as copper.

[0101] The sputtering target can be obtained, for example, by a manufacturing method including at least a step of grinding the sintered body according to this embodiment (hereinafter, this may be referred to as a processing step), and a step of bonding the sintered body to a backing plate (hereinafter, this may be referred to as a bonding step).

[0102] The processing step is a processing step in which the sintered body is at least cut into a shape suitable for installation in a sputtering device. Grinding is preferably performed to a depth of 0.3 mm or more. The grinding depth is preferably 0.5 mm or more, and particularly preferably 2 mm or more. By grinding to a depth of 0.3 mm or more, it is possible to remove portions of the crystal structure near the surface that have changed.

[0103] The oxide sintered body is preferably ground, for example, by a surface grinder to obtain a material having an average surface roughness Ra of 5 μm or less. Furthermore, the sputtering surface of the sputtering target is subjected to mirror finishing to obtain a material having an average surface roughness Ra of 1000×10 －１０ The polishing surface may be 0.05 mm or less. This mirror finish (polishing) can be achieved by using known polishing techniques such as mechanical polishing, chemical polishing, and mechanochemical polishing (a combination of mechanical polishing and chemical polishing). For example, the surface may be polished to #2000 or higher using a fixed abrasive polisher (using water as the polishing liquid), or the surface may be lapped with a free abrasive lap (using SiC paste or the like as the abrasive), and then the abrasive may be replaced with diamond paste for lapping. The polishing method is not limited to these methods.

[0104] After the grinding process, the sintered body is preferably cleaned by air blowing or running water washing. When removing foreign matter by air blowing, removal can be made more effective by using a dust collector to suck air from the opposite side of the nozzle. However, since there is a limit to the cleaning power of air blowing and running water washing, ultrasonic cleaning or the like can also be performed. An effective ultrasonic cleaning method is to use multiple oscillations at a frequency between 25 kHz and 300 kHz. For example, it is recommended to perform ultrasonic cleaning by multiple oscillations at 12 different frequencies in 25 kHz increments between 25 kHz and 300 kHz.

[0105] The bonding step is a step of bonding the sintered body after the processing step to a backing plate with a low melting point metal (for example, metallic indium, metallic gallium, etc.).

[0106] According to the sputtering target of this embodiment, a target having the same atomic composition as the sintered body of this embodiment (either the sintered body of the first aspect or the sintered body of the second aspect) is used, so that the TFT obtained by sputtering has excellent processability and is also able to obtain a TFT with high mobility and excellent in-plane uniformity of optical reliability. Furthermore, by using the sintered body of the second aspect of the sintered body of this embodiment, even when a large panel is manufactured using a large-scale device, sputtering can be performed with the occurrence of cracks in the target suppressed.

[0107] 3. Oxide Thin Film The oxide thin film according to this embodiment is an oxide thin film formed using the sputtering target according to this embodiment. The oxide thin film according to this embodiment is obtained by deposition using the sputtering target according to this embodiment. The oxide thin film according to this embodiment is preferably obtained by a manufacturing method including, for example, a step of depositing an oxide thin film by sputtering using the sputtering target according to this embodiment (hereinafter, sometimes referred to as an oxide thin film deposition step) and a step of subjecting the oxide thin film to a heat treatment (hereinafter, sometimes referred to as a heat treatment step). The oxide thin film according to this embodiment is deposited using a target having the same atomic composition as the sintered body according to this embodiment, and therefore, a TFT having excellent processability, high mobility, and excellent in-plane uniformity of optical reliability can be obtained. Note that in this embodiment, a crystalline oxide thin film may be referred to as a "crystalline oxide thin film."

[0108] In the film formation process by sputtering, one or more gases selected from the group consisting of argon, hydrogen, and oxygen, which are substantially free of impurity gases, are used as the sputtering gas. The "impurities" contained in the sputtering gas refer to trace elements that are not intentionally added and do not substantially affect the sputtering performance.

[0109] The atomic composition ratio of an oxide thin film obtained by sputtering reflects the atomic composition ratio of the oxide sintered body in the sputtering target. Therefore, it is preferable to form a film using a sputtering target containing an oxide sintered body having an atomic composition ratio similar to that of the desired oxide thin film.

[0110] The target used in the sputtering method preferably has an impurity metal content of 500 ppm or less, more preferably 100 ppm or less. The content of impurity metals in the target can be measured by ICP or SIMS, as with the oxide sintered body. The "impurities" contained in the target refer to trace elements that are not intentionally added and are mixed in the raw materials or manufacturing process, and do not substantially affect the performance of the target and semiconductor, and the "impurity metals" refer to metal elements among the elements considered as "impurities."

[0111] The crystalline state of the oxide thin film obtained by sputtering using the sputtering target according to this embodiment and one or more gases selected from the group consisting of argon and oxygen substantially containing no impurities as sputtering gas is a solid-phase crystallized oxide thin film. Whether the crystalline state of the oxide thin film is solid-phase crystallized can be determined by pretreating a cross section of the oxide thin film in a TFT element and observing the cross section of the pretreated oxide thin film with a transmission electron microscope (TEM). Solid-phase crystallization refers to a state in which the grain boundaries of the oxide thin film are continuously connected from the bottom surface to the surface, and the average grain boundary angle θ between the bottom surface of the oxide thin film and the grain boundaries is 70° or more and 110° or less.

[0112] In the oxide thin film formation process, the sputtering target according to this embodiment is used, and one or more gases selected from the group consisting of argon and oxygen, which are substantially free of impurity gases, are used as sputtering gases to form an oxide thin film by sputtering (see, for example, FIG. 5A , which shows a state in which an oxide thin film 83 has been formed on a glass substrate 81).

[0113] The phrase "the sputtering gas is substantially free of impurity gases" means that impurity gases other than argon, hydrogen, and oxygen are not actively introduced, except for adsorbed water brought in with the gas introduction, and gases that cannot be eliminated (unavoidable impurity gases) such as gases leaking from the chamber or adsorbed gases. In this embodiment, for example, a commercially available mixed gas of high-purity argon and high-purity oxygen can be used as the sputtering gas. It is preferable to eliminate impurities from the sputtering gas if possible.

[0114] The proportion of impurity gas in the sputtering gas is preferably 0.1% by volume or less, more preferably 0.05% by volume or less. If the proportion of impurity gas is 0.1% by volume or less, crystallization of the oxide thin film proceeds without any problems. The purity of the high-purity argon and high-purity oxygen is preferably 99% by volume or more, more preferably 99.9% by volume or more, and even more preferably 99.99% by volume or more.

[0115] The oxygen partial pressure in the mixed gas of argon and oxygen is preferably more than 0% by volume and not more than 20% by volume, more preferably more than 0% by volume and not more than 5% by volume. If the oxygen partial pressure is more than 0% by volume and not more than 20% by volume, the oxide thin film easily crystallizes and becomes a semiconductor when heated. By changing the oxygen partial pressure, the degree of oxidation of the oxide thin film, i.e., the degree of crystallization, can be adjusted. The oxygen partial pressure can be selected appropriately as needed.

[0116] The magnetic flux density during sputtering is preferably 700 G (gauss) or more. If the magnetic flux density during sputtering is 700 G (gauss) or more, the plasma density during sputtering film formation can be increased, the density of the oxide thin film increases, and crystal nuclei are easily formed during annealing after patterning, resulting in the crystal grains being able to be controlled to be small. Even if the magnetic flux density during sputtering is less than 700 G (gauss), the power density during sputtering can be controlled to 2.5 kW / cm. ２ By setting the temperature to the above level, the plasma density during sputtering deposition can be increased, and as a result, the crystal grains in the oxide thin film can be controlled to be small.

[0117] In the oxide thin film forming step, the sputtering target according to this embodiment is preferably mounted in an RF magnetron sputtering device or a DC magnetron sputtering device and sputtered.

[0118] The oxide thin film according to this embodiment can also be manufactured as a part of a laminate including, for example, an oxide thin film and a protective film. When a protective film is formed on a crystalline oxide thin film, it is also preferable to heat-treat the obtained oxide thin film in an oxidizing atmosphere and then form the protective film on the oxide thin film. Examples of materials for the protective film include SiO ２ , SiN ｘ , SiON ｘ , Al ２ O ３ and Ga ２ O ３ The thickness of the protective film is usually 50 nm or more and 500 nm or less. Examples of the method for forming the protective film include a CVD method, a sputtering method, and a coating method. For example, FIG. 5B shows a case where a SiO 2 protective film is formed on the oxide thin film 83 of FIG. 5A. ２ The film 85 is shown formed.

[0119] Next, a heat treatment is performed after forming the oxide thin film, after forming the protective film, or after both steps. This heat treatment is sometimes called annealing. The temperature of the heat treatment is preferably 250°C or higher and 500°C or lower, more preferably 280°C or higher and 470°C or lower, and even more preferably 300°C or higher and 450°C or lower. If the heat treatment temperature after forming the oxide thin film is 250°C or higher, the oxide thin film is likely to crystallize. If the heat treatment temperature after forming the oxide thin film is 500°C or lower, abnormal crystal growth and enlargement of crystal grains can be suppressed.

[0120] The heating time in the heat treatment step is preferably 0.1 to 5 hours, more preferably 0.3 to 3 hours, and even more preferably 0.5 to 2 hours. If the heating time in the heat treatment step is 0.1 hours or more, the oxide thin film is likely to crystallize without failure to crystallize. If the heating time in the heat treatment step is 5 hours or less, it is economically efficient. "Heating time" refers to the time during which a predetermined maximum temperature is maintained during heat treatment (i.e., the retention time).

[0121] The temperature rise rate in the heat treatment step is preferably 2°C / min or more and 40°C / min or less, and more preferably 3°C / min or more and 20°C / min or less. If the temperature rise rate in the heat treatment step is 2°C / min or more, the production efficiency of the oxide thin film is improved compared to when it is less than 1°C / min. If the temperature rise rate in the heat treatment step is 40°C / min or less, the metal elements are uniformly diffused during crystallization, and crystals without metal segregation at grain boundaries can be formed. Furthermore, the temperature rise rate in the heat treatment step is different from a value calculated from the set temperature and set time of the furnace, but is a value obtained by dividing the actual temperature of the oxide thin film by time. The actual temperature of the oxide thin film can be determined, for example, by measuring an area within 1 cm of the oxide thin film in the furnace with a thermocouple.

[0122] The heat treatment step is preferably carried out in an air atmosphere.

[0123] The heat treatment step is preferably performed after patterning the oxide thin film. By performing the heat treatment step after patterning the oxide thin film, crystallization can be promoted while removing excess oxygen present in the film during film formation and organic substances attached during patterning. As a result, a film free of organic substances and excess oxygen within the crystal grains and with fewer crystal defects can be formed, resulting in the formation of an oxide thin film with fewer electron traps and excellent conductivity. It is preferable to perform a further heat treatment step after forming the gate insulating film and before forming the contact holes, or after forming the gate insulating film and the contact holes. The heat treatment step performed after patterning the oxide thin film is sometimes referred to as the first heat treatment step, and the heat treatment step performed after forming the gate insulating film and before forming the contact holes, or after forming the gate insulating film and the contact holes, is sometimes referred to as the second heat treatment step. The second heat treatment step is preferably performed at an annealing temperature higher than that of the first heat treatment step. By annealing the gate insulating film after its formation, hydrogen contained in the gate insulating film diffuses into the oxide thin film, terminating crystal defects present on the surface of the oxide thin film with hydroxyl groups. As a result, an oxide thin film with few electron traps and good conductivity can be formed.

[0124] The method for producing an oxide thin film according to this embodiment makes it possible to obtain a crystalline oxide thin film. The method for producing an oxide thin film according to this embodiment makes it easier to obtain TFTs that are easy to process and have high mobility and excellent in-plane uniformity of optical reliability, even when large panels are produced using large-scale equipment.

[0125] The oxide thin film (crystalline oxide thin film) according to this embodiment can be applied to various integrated circuits such as logic circuits, memory circuits, and differential amplifier circuits, and can be applied to electronic devices, etc. The oxide thin film (crystalline oxide thin film) according to this embodiment can also be applied as a part of a layer in a solar cell, and a part of a layer in a display device such as a liquid crystal element, an organic electroluminescence element, an inorganic electroluminescence element, a micro organic EL display, a micro LED (light emitting diode) display, and a mini LED display. Furthermore, the oxide thin film (crystalline oxide thin film) according to this embodiment can be applied as a part of a layer in a solid-state imaging element, an X-ray sensor, a power semiconductor element, a touch panel, an LSI (large scale integrated circuit), a resistance change type memory, a DRAM (dynamic random access memory), a ferroelectric memory, a BEOL (back end of line), and a microprocessor. The oxide thin film (crystalline oxide thin film) according to this embodiment can also be used as a semiconductor layer of a field-effect transistor, a static induction transistor, a quantum tunnel field-effect transistor, a Schottky barrier transistor, a Schottky diode, a PN diode, and a resistor element, or as a part of any of these layers.

[0126] 4. Thin Film Transistor and Electronic Device The thin film transistor according to this embodiment is a thin film transistor including the oxide thin film according to this embodiment. The thin film transistor according to this embodiment is obtained by using the oxide semiconductor film according to this embodiment. The thin film transistor according to this embodiment uses an oxide thin film formed using a target having the same atomic composition as the sintered body according to this embodiment, so that a TFT having excellent processability, high mobility, and in-plane uniformity of optical reliability can be obtained. A TFT having excellent processability, high mobility, and in-plane uniformity of optical reliability can be obtained.

[0127] The thin film transistor (TFT) according to this embodiment includes, for example, an electrode, the oxide thin film according to this embodiment, and an insulating film. Examples of the electrodes include a source electrode, a drain electrode, and a gate electrode, and examples of the insulating film include a gate insulating film and a protective film. In the thin film transistor according to this embodiment, the oxide thin film is preferably in contact with the source electrode.

[0128] The TFT according to this embodiment may have, for example, a conventionally known structure.

[0129] The TFT according to this embodiment can be manufactured by employing the method for manufacturing an oxide thin film according to this embodiment. Specifically, this manufacturing method includes a step of forming an oxide thin film by sputtering using the sputtering target according to this embodiment (oxide thin film formation step) and a step of heat-treating the oxide thin film (heat treatment step). The oxide thin film formation step is preferably a step of forming an oxide thin film by sputtering using the sputtering target according to this embodiment and one or more gases selected from the group consisting of argon, hydrogen, and oxygen, which are substantially free of impurity gases, as sputtering gases. The conditions for the oxide thin film formation step and the heat treatment step are as described above in the method for manufacturing an oxide thin film. The source electrode, the drain electrode, the gate electrode, and the gate insulating film can be formed using known materials and methods.

[0130] The shape of the thin film transistor according to this embodiment is not particularly limited, and is preferably a back channel etch type transistor, an etch stopper type transistor, a top gate type transistor, a double gate type transistor, etc. Each transistor may also have a self-aligned structure.

[0131] Specific examples of thin film transistors are shown in Figures 6A, 6B, 6C, and 6D. As shown in Figure 6A, a thin film transistor 100 includes a silicon wafer 20, a gate insulating film 30, an oxide thin film 40, a source electrode 50, a drain electrode 60, and interlayer insulating films 70 and 70A.

[0132] The silicon wafer 20 is a gate electrode, and is provided on the gate insulating film 30 so as to face the oxide thin film 40 with the gate insulating film 30 in between. The gate insulating film 30 is an insulating film that blocks electrical conduction between the gate electrode and the oxide thin film 40, and is provided on the silicon wafer 20 and on one surface of the oxide thin film 40. The oxide thin film 40 is a channel layer, and is provided on the gate insulating film 30. The oxide thin film 40 is an oxide thin film (crystalline oxide thin film) according to this embodiment.

[0133] The source electrode 50 and the drain electrode 60 are conductive terminals for passing source current and drain current through the oxide thin film 40, and are provided so as to be in contact with the vicinity of both ends of the oxide thin film 40, and are electrically connected to the oxide thin film 40. The interlayer insulating film 70 is an insulating film that blocks conduction except at the contact portions between the source electrode 50 and the drain electrode 60 and the oxide thin film 40. The interlayer insulating film 70A is an insulating film that blocks conduction except at the contact portions between the source electrode 50 and the drain electrode 60 and the oxide thin film 40. The interlayer insulating film 70A is also an insulating film that blocks conduction between the source electrode 50 and the drain electrode 60. The interlayer insulating film 70A also functions as a channel layer protective layer.

[0134] 6B , the structure of the thin-film transistor 100A is similar to that of the thin-film transistor 100, but differs from the thin-film transistor 100 in that the source electrode 50 and the drain electrode 60 are provided so as to be in contact with both the gate insulating film 30 and the oxide thin film 40. The thin-film transistor 100A also differs from the thin-film transistor 100 in that an interlayer insulating film 70B is provided integrally so as to cover the gate insulating film 30, the oxide thin film 40, the source electrode 50, and the drain electrode 60.

[0135] There are no particular limitations on the materials forming the drain electrode 60, the source electrode 50, and the gate electrode, and any commonly used material can be selected. In the examples shown in FIGS. 6A and 6B, a silicon wafer is used as the substrate, and the silicon wafer also functions as the electrode, but the electrode material is not limited to silicon. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and tin oxide (SnO ２6A and 6B, a gate electrode may be formed on a substrate such as glass.

[0136] The material for forming the interlayer insulating films 70, 70A, and 70B is not particularly limited, and any commonly used material can be selected. ｘ , M.N. ｘ , and M.O. ｘ N ｙ (where M is a metal element, and x and y are real numbers greater than 0. The same applies to x and y in the compounds exemplified below.) Specific examples of the material include SiO ２ , SiO ｘ , SiN ｘ , and SiN ｘ O ｙ Furthermore, the material can be, for example, Al ２ O ３ , Ta ２ O ５ , TiO ２ , MgO, ZrO ２ , CeO ２ , K. ２ O, Li ２ O, Na ２ O, Rb ２ O, Sc ２ O ３ , Y ２ O ３ , HfO ２ , CaHfO ３ , PbTiO ３ ,BaTa ２ O ６ , SrTiO ３ , Sm ２ O ３Compounds such as AlN can also be used. The valence of the anions (oxygen anions and nitrogen anions) in these oxide compounds and nitride compounds is not particularly limited as long as it is a real number greater than 0.

[0137] When the thin film transistor according to this embodiment is a back channel etch type (bottom gate type), it is preferable to provide a protective film on the drain electrode, the source electrode, and the channel layer. By providing the protective film, the durability of the TFT is likely to be improved even when the TFT is driven for a long time.

[0138] When the thin-film transistor according to this embodiment is a top-gate TFT, for example, it has a structure in which an interlayer insulating film is formed on a substrate as a buffer layer and a gate insulating film is formed on a channel layer. As shown in FIG. 6C , the thin-film transistor 100B includes a substrate 21, a buffer layer 22, a channel layer (crystalline oxide thin film) 11, a first low-resistance region 11A-1, a second low-resistance region 11A-2 (crystalline oxide thin film), a semiconductor region 11B (crystalline oxide thin film), a gate insulating film 24, a gate electrode 25, an interlayer insulating film 26, a source electrode 27, a drain electrode 28, and a protective film 29. In the thin-film transistor 100B, the first low-resistance region 11A-1 and the second low-resistance region 11A-2 are formed, for example, by dry processes such as ion implantation and plasma treatment. An electrode layer may also be provided between the substrate 21 and the buffer layer 22 as a write shield layer.

[0139] 6D , in the case where the thin-film transistor according to the present embodiment is a top-gate TFT, a thin-film transistor 100C has a similar configuration to the thin-film transistor 100B, except that the interlayer insulating film 26 has a two-layer structure (a first interlayer insulating film 26-1 and a second interlayer insulating film 26-2). In the thin-film transistor 100C, the first low-resistance region 11A-1 and the second low-resistance region 11A-2 are formed by, for example, ion implantation.

[0140] There is no particular limitation on the materials for forming the drain electrode 28, the source electrode 27, and the gate electrode 25, and any commonly used material can be selected. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and tin oxide (SnO ２ ), or a metal electrode such as Al (aluminum), Ag (silver), Cu (copper), Cr (chromium), Ni (nickel), Mo (molybdenum), Au (gold), Ti (titanium), W (tungsten), and Ta (tantalum), or a metal electrode or laminated electrode of an alloy containing these metals can be used.

[0141] 6C and 6D, the substrate 21 may be a flexible substrate such as a polyimide substrate, or a silicon substrate, in addition to a glass substrate.

[0142] There are no particular limitations on the materials for forming the buffer layer 22, the interlayer insulating film 26, the first interlayer insulating film 26-1, the second interlayer insulating film 26-2, and the protective film 29, and any commonly used material can be selected. ｘ , M.N. ｘ , and M.O. ｘ N ｙ (where M is a metal element, and x and y are real numbers greater than 0. The same applies to x and y in the compounds exemplified below.) Specific examples of the material include SiO ２ , SiO ｘ , SiN ｘ , and SiN ｘ O ｙ Furthermore, the material may be, for example, Al ２ O ３ , Ta ２ O ５ , TiO ２ , MgO, ZrO ２ , CeO ２ , K. ２ O, Li ２ O, Na ２ O, Rb ２ O, Sc ２ O ３ , Y ２ O ３, HfO ２ , CaHfO ３ , PbTiO ３ ,BaTa ２ O ６ , SrTiO ３ , Sm ２ O ３ Compounds such as AlN can also be used. The valence of the anions (oxygen anions and nitrogen anions) in these oxide compounds and nitride compounds is not particularly limited as long as it is a real number greater than 0.

[0143] The buffer layer, protective film, and insulating film can be formed by, for example, CVD. Forming a protective film or insulating film by CVD can sometimes be a high-temperature process. Furthermore, since the protective film or insulating film often contains impurity gases immediately after deposition, it is preferable to perform a heat treatment (annealing treatment). By removing the impurity gases through the heat treatment, the protective film or insulating film becomes a stable film, facilitating the formation of highly durable TFT elements. Furthermore, by performing annealing after the formation of the gate insulating film, hydrogen contained in the gate insulating film diffuses into the oxide thin film, terminating crystal defects present on the surface of the oxide thin film with hydroxyl groups, resulting in the formation of an oxide thin film with few electron traps and good conductivity.

[0144] By using the oxide thin film according to this embodiment, the thin film transistor according to this embodiment is less susceptible to the influence of temperature in the CVD process and the influence of subsequent heat treatment. Therefore, even when a protective film or an insulating film is formed, the stability of the TFT characteristics can be improved.

[0145] In the thin film transistor according to this embodiment, the threshold voltage (Vth) is preferably −2.0 V or more and 2.0 V or less. When the threshold voltage (Vth) is −2.0 V or more and 2.0 V or less, a Vth correction circuit can be installed in the TFT to correct Vth to 0 V. When the TFT obtained in this way is installed in a panel, the display can be driven without uneven brightness or burn-in. The threshold voltage (Vth) is more preferably −1.5 V or more and 1.5 V or less, and even more preferably −1.0 V or more and 1.0 V or less.

[0146] From the graph of transfer characteristics, the threshold voltage (Vth) is calculated as follows: －９ It can be defined as the gate voltage Vg at A. The on-off ratio is 10 ６ That's it, 10 １２ The following is preferred: ７ That's it, 10 １１ More preferably, 10 or less ８ That's it, 10 １０ More preferably, the on-off ratio is 10 or less. ６ If the on-off ratio is 10 or more, the liquid crystal display can be driven. １２ When the on-off ratio is 10 or less, an organic EL element with high contrast can be driven. １２ If the off-state current is 10 －１２ A or less, and when used in the transfer transistor or reset transistor of a CMOS image sensor, it is possible to extend the image retention time and improve the sensitivity.

[0147] The on-off ratio is determined by determining the ratio [on current value / off current value], where the value of Id when Vg = -10 V is the off current value and the value of Id when Vg = 20 V is the on current value. －１０ A or less is preferable, and 10 －１１ A or less is more preferable, and 10 －１２ A or less is more preferable. －１０ When the resistance is A or less, it is possible to drive an organic EL device with high contrast. Furthermore, when used in the transfer transistor or reset transistor of a CMOS image sensor, it is possible to extend the image retention time and improve the sensitivity.

[0148] In the thin film transistor according to this embodiment, the linear mobility is 25 cm ２ The linear mobility is expressed by the transconductance (Gm) for each Vg calculated from the graph of transfer characteristics, and the maximum mobility in the Vg range from -15 V to 20 V can be defined as the linear mobility.

[0149] In the thin film transistor according to this embodiment, die(0 0) refers to a TFT element fabricated in the center of the TFT substrate. ΔVth in the die(0 0) TFT is preferably −2.0 V or more. If ΔVth in die(0 0) is −2.0 V or more, the thin film transistor has excellent optical reliability. die(0 -5) refers to a TFT fabricated at a position 3 cm away from die(0 0) on the TFT substrate. ΔVth in die(0 -5) is preferably −6.0 V or more. If ΔVth in die(0 -5) is −6.0 V or more, the thin film transistor has excellent optical reliability. In this embodiment, the difference in thickness of the crystalline oxide thin film between the die(0 0) and die(0 -5) TFT elements is 10%, and the difference in the in-plane position of the TFT can be considered as a variation due to the difference in thickness of the crystalline oxide thin film. Also, ΔVth means the change in Vth before and after the application of bias stress.

[0150] <Quantum Tunnel Field Effect Transistor> The crystalline oxide thin film according to this embodiment can also be used in a quantum tunnel field effect transistor (FET), which may also be referred to as a quantum tunnel field effect transistor.

[0151] 7 is a schematic diagram (longitudinal cross-sectional view) of a quantum tunnel field effect transistor (FET) according to this embodiment. The quantum tunnel field effect transistor 501 includes a p-type semiconductor layer 503, an n-type semiconductor layer 507, a gate insulating film 509, a gate electrode 511, a source electrode 513, and a drain electrode 515.

[0152] The p-type semiconductor layer 503, the n-type semiconductor layer 507, the gate insulating film 509, and the gate electrode 511 are stacked in this order. The source electrode 513 is provided on the p-type semiconductor layer 503. The drain electrode 515 is provided on the n-type semiconductor layer 507. The p-type semiconductor layer 503 is a p-type Group IV semiconductor layer, and in this case is a p-type silicon layer. The n-type semiconductor layer 507 is an n-type oxide thin film used in the image sensor according to this embodiment. The source electrode 513 and the drain electrode 515 are conductive films.

[0153] 7, an insulating layer may be formed on the p-type semiconductor layer 503. In this case, the p-type semiconductor layer 503 and the n-type semiconductor layer 507 are connected via a contact hole, which is a region where the insulating layer is partially opened. Although not shown in FIG. 7, the quantum tunnel field effect transistor 501 may also have an interlayer insulating film covering its upper surface.

[0154] The quantum tunnel field effect transistor 501 is a quantum tunnel field effect transistor (FET) that performs current switching by controlling the current tunneling through an energy barrier formed by a p-type semiconductor layer 503 and an n-type semiconductor layer 507 using the voltage of a gate electrode 511. In this structure, the band gap of the oxide semiconductor that constitutes the n-type semiconductor layer 507 is large, and the off-current can be reduced.

[0155] FIG. 8 shows a schematic diagram (longitudinal cross-sectional view) of a quantum tunnel field-effect transistor 501A according to another embodiment. The quantum tunnel field-effect transistor 501A has the same configuration as the quantum tunnel field-effect transistor 501, except that a silicon oxide layer 505 is formed between a p-type semiconductor layer 503 and an n-type semiconductor layer 507. The presence of the silicon oxide layer reduces the off-state current. The thickness of the silicon oxide layer 505 is preferably 10 nm or less. By making the thickness of the silicon oxide layer 505 10 nm or less, it is possible to prevent tunneling current from flowing, the formation of an energy barrier from being difficult, and changes in the barrier height, thereby preventing a decrease or change in the tunneling current. The thickness of the silicon oxide layer 505 is preferably 8 nm or less, more preferably 5 nm or less, even more preferably 3 nm or less, and even more preferably 1 nm or less.

[0156] In the quantum tunnel field effect transistors 501 and 501A, the n-type semiconductor layer 507 is also an n-type oxide semiconductor.

[0157] The oxide semiconductor constituting the n-type semiconductor layer 507 may be amorphous. When the oxide semiconductor constituting the n-type semiconductor layer 507 is amorphous, it can be etched with an organic acid such as oxalic acid, the difference in etching rate with other layers becomes large, and good etching can be achieved without affecting metal layers such as wiring.

[0158] The oxide semiconductor constituting the n-type semiconductor layer 507 may be crystalline. When the oxide semiconductor constituting the n-type semiconductor layer 507 is crystalline, the band gap becomes larger than in the case of an amorphous material, and the off-current can be reduced. Since the work function can also be increased, it becomes easier to control the current tunneling through the energy barrier formed by the p-type Group IV semiconductor material and the n-type semiconductor layer 507.

[0159] The method for manufacturing the quantum tunnel field effect transistor 501 is not particularly limited, but the following method can be exemplified. First, as shown in Fig. 9A, an insulating film 505A is formed on a p-type semiconductor layer 503, and a part of the insulating film 505A is opened by etching or the like to form a contact hole 505B. Next, as shown in Fig. 9B, an n-type semiconductor layer 507 is formed on the p-type semiconductor layer 503 and the insulating film 505A. At this time, the p-type semiconductor layer 503 and the n-type semiconductor layer 507 are connected via the contact hole 505B.

[0160] 9C, a gate insulating film 509 and a gate electrode 511 are formed in this order on the n-type semiconductor layer 507. Next, as shown in FIG. 9D, an interlayer insulating film 519 is provided so as to cover the insulating film 505A, the n-type semiconductor layer 507, the gate insulating film 509, and the gate electrode 511.

[0161] 9E, a contact hole 519A is formed by opening a portion of the insulating film 505A and interlayer insulating film 519 on the p-type semiconductor layer 503, and a source electrode 513 is provided in the contact hole 519A. Furthermore, as shown in FIG. 9E, a contact hole 519B is formed by opening a portion of the gate insulating film 509 and interlayer insulating film 519 on the n-type semiconductor layer 507, and a drain electrode 515 is formed in the contact hole 519B. Through the above procedure, the quantum tunnel field effect transistor 501 can be manufactured.

[0162] After forming n-type semiconductor layer 507 on p-type semiconductor layer 503, heat treatment is performed at a temperature of 150° C. or higher and 600° C. or lower, thereby forming silicon oxide layer 505 between p-type semiconductor layer 503 and n-type semiconductor layer 507. By adding this step, quantum tunnel field effect transistor 501A can be manufactured.

[0163] The thin film transistor according to this embodiment can be suitably used in solar cells, display elements (liquid crystal elements, organic electroluminescence elements, inorganic electroluminescence elements, etc.), and power semiconductor elements. The thin film transistor according to this embodiment can be suitably used as a transistor in devices that use an active matrix system, such as display devices (liquid crystal displays, organic EL (Electro Luminescence) displays, micro organic EL displays, micro LED (Light Emitting Diode) displays, and mini LED displays, etc.), solid-state imaging devices, and touch panels.

[0164] The thin film transistor according to this embodiment can be applied to various integrated circuits such as field effect transistors, logic circuits, memory circuits, and differential amplifier circuits, and these can be applied to electronic devices, etc. The electronic devices according to this embodiment preferably include a thin film transistor. Furthermore, the thin film transistor according to this embodiment can be applied to static induction transistors and Schottky barrier transistors in addition to field effect transistors. The thin film transistor according to this embodiment can also be applied as a transistor for sensors such as image sensors, X-ray sensors, and biosensors.

[0165] Hereinafter, the case where the thin film transistor according to this embodiment is used in a display device and a solid-state image sensor will be described.

[0166] First, a case where the thin film transistor according to this embodiment is used in a display device will be described with reference to Figures 10A to 10C. Figure 10A is a top view of the display device according to this embodiment. Figure 10B is a circuit diagram for explaining the circuit of the pixel portion when a liquid crystal element is applied to the pixel portion of the display device according to this embodiment. Also, Figure 10C is a circuit diagram for explaining the circuit of the pixel portion when an organic EL element is applied to the pixel portion of the display device according to this embodiment.

[0167] The thin film transistor according to this embodiment can be used as a transistor disposed in a pixel portion. Since the thin film transistor according to this embodiment can be easily made into an n-channel type, part of a driver circuit that can be configured with an n-channel transistor is formed over the same substrate as the transistor in the pixel portion. By using the thin film transistor shown in this embodiment in the pixel portion or the driver circuit, a display device with high optical reliability can be provided.

[0168] 10A shows an example of a top view of an active matrix display device. A pixel portion 301, a first scanning line driver circuit 302, a second scanning line driver circuit 303, and a signal line driver circuit 304 are formed on a substrate 300 of the display device. A plurality of signal lines are arranged in the pixel portion 301, extending from the signal line driver circuit 304, and a plurality of scanning lines are arranged in the pixel portion 301, extending from the first scanning line driver circuit 302 and the second scanning line driver circuit 303. Pixels each having a display element are provided in a matrix at an intersection between the scanning lines and the signal lines. The substrate 300 of the display device is connected to a timing control circuit (also referred to as a controller or a control IC) via a connection portion such as an FPC (Flexible Printed Circuit).

[0169] 10A , the first scanning line driver circuit 302, the second scanning line driver circuit 303, and the signal line driver circuit 304 are formed on the same substrate 300 as the pixel portion 301. This reduces the number of components, such as driver circuits, that are provided externally, thereby reducing costs. Furthermore, if the driver circuits are provided externally to the substrate 300, it becomes necessary to extend the wiring, which increases the number of connections between the wiring. If the driver circuits are provided on the same substrate 300, the number of connections between the wiring can be reduced, thereby improving optical reliability or yield.

[0170] 10B shows an example of a circuit configuration of a pixel, which is applicable to the pixel portion of a VA-type liquid crystal display device.

[0171] This pixel circuit can be applied to a configuration in which one pixel has multiple pixel electrodes. Each pixel electrode is connected to a different transistor, and each transistor is configured to be driven by a different gate signal. This allows the signals applied to each pixel electrode of a multi-domain pixel to be controlled independently.

[0172] The gate wiring 312 of the transistor 316 and the gate wiring 313 of the transistor 317 are separated so as to receive different gate signals. On the other hand, the source or drain electrode 314 functioning as a data line is used in common by the transistors 316 and 317. The thin film transistors according to this embodiment can be used for the transistors 316 and 317. This makes it possible to provide a liquid crystal display device with high optical reliability.

[0173] The transistor 316 is electrically connected to a first pixel electrode, and the transistor 317 is electrically connected to a second pixel electrode. The first pixel electrode and the second pixel electrode are separated from each other. The shapes of the first pixel electrode and the second pixel electrode are not particularly limited. For example, the first pixel electrode may be V-shaped.

[0174] The gate electrode of the transistor 316 is connected to the gate wiring 312, and the gate electrode of the transistor 317 is connected to the gate wiring 313. By applying different gate signals to the gate wiring 312 and the gate wiring 313, the operation timing of the transistors 316 and 317 can be made different, thereby controlling the alignment of the liquid crystal.

[0175] Furthermore, a storage capacitor may be formed by the capacitor wiring 310, a gate insulating film that functions as a dielectric, and a capacitor electrode that is electrically connected to the first pixel electrode or the second pixel electrode.

[0176] The multi-domain structure has one pixel having a first liquid crystal element 318 and a second liquid crystal element 319. The first liquid crystal element 318 is composed of a first pixel electrode, a counter electrode, and a liquid crystal layer therebetween, and the second liquid crystal element 319 is composed of a second pixel electrode, a counter electrode, and a liquid crystal layer therebetween.

[0177] The pixel portion is not limited to the configuration shown in Fig. 10B, and may include a switch, a resistor, a capacitor, a transistor, a sensor, or a logic circuit.

[0178] Another example of the circuit configuration of a pixel is shown in Fig. 10C, which shows the structure of a pixel portion of a display device using an organic EL element.

[0179] 10C is a diagram showing an example of an applicable circuit for the pixel portion 320. Here, an example is shown in which two n-channel transistors are used in one pixel. The oxide thin film (crystalline oxide thin film) according to this embodiment can be used in the channel formation region of the n-channel transistor. Digital time grayscale driving can be applied to the circuit for the pixel portion.

[0180] The thin film transistor according to this embodiment can be used for the switching transistor 321 and the driving transistor 322. This makes it possible to provide an organic EL display device with high optical reliability.

[0181] The configuration of the circuit of the pixel portion is not limited to the configuration shown in Fig. 10C. A switch, a resistive element, a capacitive element, a sensor, a transistor, or a logic circuit may be added to the circuit of the pixel portion shown in Fig. 10C. Furthermore, a display device using the thin film transistor according to this embodiment may include both a Si-based transistor and the crystalline oxide transistor of this embodiment.

[0182] Next, a case where the thin film transistor according to this embodiment is used in a solid-state imaging device will be described with reference to FIG.

[0183] A CMOS (Complementary Metal Oxide Semiconductor) image sensor is a solid-state imaging device that holds a potential in a signal charge storage section and outputs that potential to a vertical output line via an amplification transistor. If a leak current occurs in the reset transistor and / or transfer transistor included in the CMOS image sensor, the leak current causes charging or discharging, changing the potential of the signal charge storage section. When the potential of the signal charge storage section changes, the potential of the amplification transistor also changes, resulting in a value that deviates from the original potential, degrading the captured image.

[0184] The following describes the operational effects when a thin film transistor according to an embodiment of the present invention is applied to a reset transistor and a transfer transistor of a CMOS image sensor. Either a thin film transistor or a bulk transistor may be applied to the amplifying transistor.

[0185] 11 is a diagram showing an example of the pixel configuration of a CMOS image sensor. A pixel is composed of a photodiode 3002, which is a photoelectric conversion element, a transfer transistor 3004, a reset transistor 3006, an amplifier transistor 3008, and various wirings, and a plurality of pixels are arranged in a matrix to form a sensor. A selection transistor electrically connected to the amplifier transistor 3008 may be provided. The transistor symbols "OS" and "Si" represent oxide semiconductor and silicon, respectively, and represent materials that are preferable for use in the respective transistors. This also applies to the subsequent drawings.

[0186] The photodiode 3002 is connected to the source side of the transfer transistor 3004, and a signal charge storage region 3010 (also called FD: floating diffusion) is formed on the drain side of the transfer transistor 3004. The source of the reset transistor 3006 and the gate of the amplification transistor 3008 are connected to the signal charge storage region 3010. As another configuration, the reset power supply line 3110 can be eliminated. For example, the drain of the reset transistor 3006 can be connected to the power supply line 3100 or the vertical output line 3120 instead of the reset power supply line 3110. Note that the photodiode 3002 may use the oxide semiconductor film of the present invention, and the same material as the oxide semiconductor films used for the transfer transistor 3004 and the reset transistor 3006 may be used.

[0187] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0188] [1] Production of Sintered Body (Examples 1 to 9) Gallium oxide powder, aluminum oxide powder, and indium oxide powder were weighed out at the charged composition ratios (mass%) shown in Tables 1 to 3 to obtain the atomic composition ratios (at%) shown in Tables 1 to 3, and raw material powders were prepared. Next, a dispersant, a thickener, and water were added to the raw material powders to prepare a slurry-like raw material mixture with a solids concentration of 50% by mass. The viscosity of the resulting raw material mixture was 200 mPa·s. The resulting raw material mixture was mixed and crushed for 2 hours using zirconia balls with a diameter of 0.5 mm in a bead mill. The mixed and crushed mixture was supplied to a spray dryer and granulated at a rotation speed of 12,000 rpm and a hot air temperature of 150°C to obtain raw material granulated powder. The raw granulated powder was passed through a 90 mesh sieve to remove raw granulated powder with a particle size exceeding 150 μm, and the raw granulated powder was classified into particles with a particle size of 150 μm or less to obtain a granulated powder. The shape of the granulated powder was spherical.

[0189] The obtained granulated powder was placed in a mold and subjected to pressure of 300 kg / cm ２ The press-molded body was produced at a pressure of 2000 kg / cm. ２The densification was carried out by CIP at a pressure of 1000 kJ / cm.

[0190] Next, the densified press-molded body was placed in an atmospheric pressure sintering furnace, where it was heated to 200°C at a heating rate of 0.2°C / min and then held at 200°C for 2 hours. The temperature was then raised to 400°C at a heating rate of 0.5°C / min and then held at 400°C for 3 hours. For Examples 1 to 8, the temperature was raised to 1350°C at a heating rate of 1°C / min and then held at 1350°C for 20 hours for sintering. For Example 9, the temperature was raised to 1400°C at a heating rate of 1°C / min and then held at 1400°C for 20 hours for sintering. After allowing to cool, a sintered oxide body was obtained. The resulting sintered body was evaluated as follows. The evaluation results are shown in Tables 1 to 3.

[0191] (Comparative Examples 1 to 12) Gallium oxide powder, aluminum oxide powder, and indium oxide powder were weighed out at the charged composition ratios (mass%) shown in Tables 4 to 6 to prepare raw material powders, so as to achieve the atomic composition ratios (at%) shown in Tables 4 to 6. The raw material powders were placed in a polyethylene pot and mixed and pulverized for 72 hours using a dry ball mill to produce mixed powders. This mixed powder was placed in a mold and subjected to a pressure of 500 kg / cm. ２ The press-molded body was produced at a pressure of 2000 kg / cm. ２ The compact was densified by CIP at a pressure of 1000 kJ / cm. The densified press-molded body was then placed in an atmospheric pressure sintering furnace, heated to 350°C at a heating rate of 0.2°C / min, and held at 350°C for 3 hours. The compact was then heated to 1350°C at a heating rate of 1.7°C / min, and held at 1350°C for 24 hours for sintering. The compact was allowed to cool, yielding an oxide sintered body. The resulting sintered body was evaluated as follows. The evaluation results are shown in Tables 4 to 6.

[0192] In Tables 1 to 6, the notation "metal composition ratio [at%]" corresponds to the above-mentioned atomic composition ratio (at%). In addition, in the "raw material ratio", the numerical value of the charge ratio shown in "mass%" indicates the mass ratio of indium oxide, gallium oxide, and aluminum oxide, and the numerical value shown in "at%" indicates the ratio of the atomic composition ratio of indium element, gallium element, and aluminum element expressed as a percentage. The same applies to Tables 7 to 16 described below. In Tables 1 to 6, the notation "mixing and pulverization" corresponds to the above-mentioned mixing and pulverization.

[0193] [2] Characterization of sintered body (2-1) Atomic composition ratio The atomic composition ratio (at %) of the sintered body was analyzed using an inductively coupled plasma atomic emission spectroscopy (ICP-AES, manufactured by Shimadzu Corporation). It was confirmed that the obtained sintered body had the atomic composition ratio (at %) shown in Tables 1 to 6. (2-2) XRD measurement and identification of crystalline phase The obtained sintered body was subjected to X-ray diffraction (XRD) measurement using an X-ray diffraction measurement device SmartLab under the following conditions. The obtained XRD chart was subjected to Rietveld analysis using PDXL2 (manufactured by Rigaku Corporation) to confirm the crystalline phase in the sintered body. - Device: SmartLab (manufactured by Rigaku Corporation) - Detector: Scintillation counter (SC-70) - X-ray: Cu-Kα ray (wavelength 1.5418 × 10 －１０ m) Intensity: 45 kV, 200 mA 2θ-θ reflection method, continuous scan (2.0° / min) Start: 5° End: 80° Sampling interval: 0.02° Slits DS (divergence slit), SS (scattering slit), RS (receiving slit): 1 mm

[0194] In the Rietveld analysis, a bixbyite structure (ICSD Inorganic Crystal Structure Database 169420) and a P-1 crystal structure were used as the initial structure. The P-1 crystal structure here is represented by the following crystal structure parameters. Here, the metal is any of In (indium), Ga (gallium), and Al (aluminum). [Space group: P-1] - Lattice constants: a = 10.07 Å, b = 10.45 Å, c = 11.01 Å, α = 111.70°, β = 107.70°, γ = 90.00° - Atomic coordinates: Atomic species: Metal, atomic coordinates (x=0.04478, y=0.36228, z=0.86934) Atomic species: Metal, atomic coordinates (x=0.12677, y=0.11682, z=0.62279) Atomic species: metal, atomic coordinates (x=0.21268, y=0.85040, z=0.38665) Atomic species: Metal, atomic coordinates (x=0.23283, y=0.11047, z=0.97132) Atomic species: Metal, atomic coordinates (x=0.28695, y=0.64349, z=0.10627) Atomic species: Metal, atomic coordinates (x=0.45663, y=0.11849, z=0.62655) Atomic species: Metal, atomic coordinates (x=0.58343, y=0.14455, z=0.00650) Atomic species: Metal, atomic coordinates (x=0.62181, y=0.64170, z=0.10725) Atomic species: Metal, atomic coordinates (x=0.68785, y=0.18413, z=0.31614) Atomic species: Metal, atomic coordinates (x=0.08662, y=0.88097, z=0.03282) Atomic species: Metal, atomic coordinates (x=0.02388, y=0.13328, z=0.30129) Atomic species: Metal, atomic coordinates (x=0.06270, y=0.60510, z=0.45610) Atomic species: Metal, atomic coordinates (x=0.15030, y=0.39620, z=0.19490) Atomic species: Metal, atomic coordinates (x=0.26240, y=0.36429, z=0.53740) Atomic species: Metal, atomic coordinates (x=0.34051, y=0.13040, z=0.29845) Atomic species: metal, atomic coordinates (x=0.40810, y=0.60820, z=0.45090) Atomic species: Metal, atomic coordinates (x = 0.48210, y = 0.39651, z = 0.22899) Atomic species: Metal, atomic coordinates (x = 0.83690, y = 0.39245, z = 0.23049) Atomic species: Oxygen, atomic coordinates (x = 0.01570, y = 0.73320, z = 0.36270) Atomic species: Oxygen, atomic coordinates (x = 0.02950, ​​y = 0.44990, z = 0.28500) Atomic species: Oxygen, atomic coordinates (x = 0.05180, y = 0.02040, z = 0.40130) Atomic species: Oxygen, atomic coordinates (x = 0.09750, y = 0.74420, z = 0.64840) Atomic species: oxygen, atomic coordinates (x = 0.10040, y = 0.23100, z = 0.06110) Atomic species: oxygen, atomic coordinates (x = 0.12100, y = 0.50540, z = 0.09290) Atomic species: oxygen, atomic coordinates (x = 0.12180, y = 0.46770, z = 0.56750) Atomic species: oxygen, atomic coordinates (x = 0.13230, y = 0.78930, z = 0.17000) Atomic species: oxygen, atomic coordinates (x = 0.19170, y = 0.20520, z = 0.83700) Atomic species: oxygen, atomic coordinates (x = 0.19980, y = 0.22930, z = 0.35780) Atomic species: oxygen, atomic coordinates (x = 0.24610, y = 0.66070, z = 0.48730) Atomic species: oxygen, atomic coordinates (x = 0.27030, y = 0.01970, z = 0.11610) Atomic species: oxygen, atomic coordinates (x = 0.29750, y = 0.25780, z = 0.64510) Atomic species: oxygen, atomic coordinates (x = 0.32740, y = 0.44290, z = 0.29080) Atomic species: oxygen, atomic coordinates (x = 0.38000, y = 0.01700, z = 0.39960) Atomic species: oxygen, atomic coordinates (x = 0.38520, y = 0.73030, z = 0.34950) Atomic species: oxygen, atomic coordinates (x = 0.40770, y = 0.23850, z = 0.06570) Atomic species: oxygen, atomic coordinates (x = 0.42500, y = 0.46540, z = 0.57450) Atomic species: oxygen, atomic coordinates (x = 0.45690, y = 0.50630, z = 0.11420) Atomic species: oxygen, atomic coordinates (x = 0.47200, y = 0.78620, z = 0.15020) Atomic species: Oxygen, atomic coordinates (x = 0.50000, y = 0.24830, z = 0.35810) Atomic species: Oxygen, atomic coordinates (x = 0.64040, y = 0.02850, z = 0.12200) Atomic species: Oxygen, atomic coordinates (x = 0.65870, y = 0.33560, z = 0.22570) Atomic species: Oxygen, atomic coordinates (x = 0.71710, y = 0.03020, z = 0.39850) Atomic species: Oxygen, atomic coordinates (x = 0.78080, y = 0.50960, z = 0.12340) Atomic species: Oxygen, atomic coordinates (x = 0.80070, y = 0.24650, z = 0.05620) Atomic species: oxygen, atomic coordinates (x = 0.96440, y = 0.02480, z = 0.11700).

[0195] In particular, the P-1 or P1 crystals are characterized by having a diffraction peak near 2θ = 6 to 14°, and the presence or absence of P-1 or P1 can be determined from this peak. Furthermore, if the diffraction peak is buried in noise, the presence or absence of crystals can be determined by performing precision measurements under the following conditions: Apparatus: D8 DISCOVER Plus (manufactured by Bruker) Detector: Eiger2R500K X-ray: Cu-Kα ray (wavelength 1.5418 × 10 －１０ m) Intensity: 45 kV, 120 mA X-ray irradiation conditions: 2θ-θ reflection method, continuous scan Start: 5° End: 80° Sampling interval: 0.02° Speed: 25 s / step Optical conditions: Twin Primary (Goebel Mirror), light source side Soller (4.0°), Slit: 1.0 mm, Twin Primary (Open), light receiving side Soller (4.0°) Detector conditions: 1D mode Tables 1 to 6 show the results of crystalline phase identification by XRD of the sintered bodies produced under each condition. In Examples 1 to 9, Comparative Examples 1 to 9, Comparative Example 11, and Comparative Example 12, a bixbyite structure and a P-1 crystal structure were confirmed. Under the conditions of Example 10, only a bixbyite structure was observed.

[0196] (2-3) Calculation of the weight ratio of the crystalline phase by XRD Fitting was performed by the Rietveld analysis until the reliability factor Rwp became less than 15%, and the weight ratio of crystals having a bixbyite structure containing In as a main component to all crystals in each sintered body was calculated. In Examples 1 to 9, Comparative Examples 1 to 9, 11, and 12, the weight ratio of the bixbyite structure in the sintered body was 70% or more.

[0197] (2-4) High-resolution SEM Measurement The state of the crystal grains of the sintered body was evaluated using a scanning electron microscope (SEM). The pore area ratio was evaluated using a scanning electron microscope (SEM). The surface of the sintered body was polished, and when the planar shape was rectangular, the surface was divided into 16 equal areas, and sintered body samples were prepared as measurement samples at 16 center points of each rectangle. The sintered body samples were prepared by cutting the sintered body into pieces of 1 cm (1 cm x 1 cm) or less, and this sintered body sample was embedded in a 1-inch φ epoxy-based room-temperature curing resin. The embedded sintered body sample was then polished using abrasive paper #400, #600, #800, 3 μm diamond suspension water, and 50 nm colloidal silica (for final finishing) in that order. The polished sintered body sample was observed under an optical microscope, and polishing was continued until there were no polishing marks of 1 μm or more on the polished surface of the sintered body sample. The state of the crystal grains of the sintered body was examined by measuring high-resolution SEM images of the polished surface of the sintered body sample using a Hitachi High-Technologies Corporation SU8200 scanning electron microscope. The high-resolution SEM images were measured at an acceleration voltage of 10.0 kV and magnifications of 2000x and 5000x. Furthermore, the high-resolution SEM images were observed in areas measuring 62 μm × 43 μm and 25 μm × 18 μm, respectively, and secondary electron images were measured.

[0198] (2-5) Measurement of Pore Area Ratio The pore area ratio in the sintered body was calculated by performing image analysis on a secondary electron image of a high-resolution SEM image using image analysis software (SPIP, Version 4.3.2.0, manufactured by Image Metrology).

[0199] First, the contrast of the secondary electron image of the SEM image was quantified using image analysis software, and a height of (maximum density - minimum density) x 1 / 5 was set as the threshold. Next, areas below the threshold were defined as pores, and the area ratio of pores to the entire image was calculated. This was calculated for each of the 16 sintered body samples (16 in total) prepared by dividing the samples into 16 sections, and this was used as the pore area ratio for each sample. Finally, the average pore area ratio for each of the 16 samples was calculated and used as the pore area ratio for the sintered bodies prepared in each Example and Comparative Example. Tables 1 to 6 show the evaluation results of the pore area ratio for the sintered bodies prepared under various conditions. In Examples 1 to 9, mixing and pulverization (i.e., mixing and crushing) during sintered body preparation were performed using a bead mill, the size of the zirconia balls was adjusted, and the drying and granulation conditions were further optimized. This enabled the production of spherical, finely granulated powder with a particle size of 150 μm or less, which was then sintered to produce good sintered bodies with a pore area ratio of 0.1% or less. Under the production conditions of Comparative Examples 1 to 12, no granulation was performed, and the area ratio of pores after sintering was as high as 0.2% or more, resulting in sintered bodies that may crack when sputtered using a large-scale device.

[0200] (2-6) Measurement of hydrogen atom concentration and carbon atom concentration The sintered body was polished using abrasive paper #600, and then the sample surface was etched to a depth of several tens of μm before analysis. The analysis was carried out by secondary ion mass spectrometry (D-SIMS). For the measurement, a CAMECA IMS-6f was used, and the primary ion species Cs ＋ The sample was irradiated with ions at a primary ion acceleration voltage of 14.5 kV, and secondary ions were measured. Furthermore, the sintered body was measured by SIMS, and the intensities of the secondary ions of H atoms and C atoms obtained were measured. Using a standard sample ZnO, which was already doped with H atoms and C atoms at known concentrations, the concentrations of H atoms and C atoms in the sintered body were calculated from the intensity ratio, and these were taken as the hydrogen atom concentration and the carbon atom concentration. In Examples 1, 4, 5, and 7, the hydrogen atom concentrations in the sintered body were 3.7 x 10 １７ [atoms / cm ３ ], 1.0 × 10 １７[atoms / cm ３ ], 5.3 × 10 １６ [atoms / cm ３ ], and 5.2 × 10 １６ [atoms / cm ３ The carbon atom concentration in Examples 1, 4, 5, and 7 was 2.2×10 １７ [atoms / cm ３ ], 2.5 × 10 １７ [atoms / cm ３ ], 3.8 × 10 １６ [atoms / cm ３ ], and 9.7 × 10 １６ [atoms / cm ３ ] was obtained, and it was confirmed that this concentration does not affect the deterioration of optical reliability.

[0201] (2-7) Flexural Strength Thirty rectangular prism-shaped test pieces measuring 3 mm thick x 4 mm wide x 36 mm long were cut from the resulting sintered body. The three-point bending strength was measured using a materials testing machine (Shimadzu EZ Graph) in accordance with JIS R 1601:2008. The average value of the three-point bending strength measurements for the 30 test pieces was taken as the flexural strength. Tables 1 to 6 show the evaluation results of the flexural strength of the sintered bodies produced under each condition. Since the amount of pores in the sintered bodies in Examples 1 to 9 was small, the flexural strength values ​​were higher than 190 MPa, and sintered bodies were obtained that could be used as sputtering targets for large-scale equipment without cracking and could be stably sputtered. Comparative Examples 1 to 12 showed values ​​lower than 190 MPa, resulting in sintered bodies that were susceptible to cracking due to the power during sputtering when used as sputtering targets for large-scale equipment.

[0202]

[0203]

[0204]

[0205]

[0206]

[0207]

[0208] [3] Production of sputtering targets and oxide thin films (Examples 1 to 9) Sputtering targets were obtained using the sintered bodies obtained in Examples 1 to 9. The metal composition ratios (unit: at %) in the obtained sputtering targets are shown in Tables 7 to 9.

[0209] Using this oxide sputtering target, a 50-nm-thick oxide semiconductor film (oxide semiconductor layer) was formed by sputtering on a silicon wafer (gate electrode) with a 100-nm-thick thermal oxide film (gate insulating film). The film formation conditions are as shown in Tables 7 to 9. A mixed gas of high-purity argon and high-purity oxygen (impurity gas concentration: 0.01% by volume) was used as the sputtering gas.

[0210] Next, the deposited oxide semiconductor layer was patterned into islands by photolithography. First, a photoresist film was formed on the oxide semiconductor layer. AZ1500 (manufactured by AZ Electronic Materials) was used as the photoresist. Exposure was performed through a photomask with a 14 μm × 4 μm pattern. After exposure, development was performed using tetramethylammonium hydroxide (TMAH). After development, the oxide semiconductor layer was etched using oxalic acid. After etching, the photoresist was peeled off to obtain a substrate with a patterned oxide thin film. The resulting semiconductor area was smaller than the photomask pattern due to the intrusion of the etching solution, measuring 12 μm × 2.8 μm.

[0211] Next, the substrate with the patterned oxide thin film was placed in a furnace, and the temperature was raised to 350°C at a rate of 10°C / min in the atmosphere, and then held for 1 hour. The inside of the furnace was held at 350°C for 1 hour, and then allowed to cool naturally. After the temperature inside the furnace returned to room temperature, the substrate with the oxide thin film was removed from the furnace.

[0212] Subsequently, an image reversal resist was spin-coated on the semiconductor patterned surface of the annealed substrate with the oxide thin film. AZ5214 (manufactured by AZ Electronic Materials) was used as the image reversal resist. After spin-coating, the resist was exposed using a photomask with a pattern of 6 μm x 6 μm. After the reversal bake process, the entire surface of the image reversal resist AZ5214 was exposed and developed with TMAH. A 300 nm thick SiO was sputtered onto the substrate with the patterned resist. ２ The sputtering conditions were as follows: Substrate temperature: 25°C Ultimate pressure: 4 x 10 －４ Pa or less Atmospheric gas: Ar + O ２ (O ２ Flow rate ratio 10%) Sputtering pressure (total pressure): 0.5 Pa Input voltage: RF 500 W Magnetic flux density: 1000 G Distance between S (substrate) and T (target): 70 mm Then, SiO ２ The substrate on which the film was formed was lifted off in acetone to obtain SiO ２ was patterned.

[0213] Furthermore, SiO ２ The substrate with the patterned oxide thin film was exposed to light through a photomask using photoresist AZ1500 (manufactured by AZ Electronic Materials), and then developed with tetramethylammonium hydroxide (TMAH). After development, the silicon wafer with the thermal oxide film was etched with buffered hydrofluoric acid (BHF) to form contact holes for connecting the gate electrodes. After the contact holes were formed, the substrate was annealed in air at 400°C for 1 hour.

[0214] Subsequently, the source / drain electrode layer was patterned by a lift-off process using image reversal resist AZ5214 and a photomask. The image reversal resist AZ5214 was exposed through a photomask formed so as to be patterned into the final device shape (L length: 6 μm, W length: 2.8 μm, Ls length of each of the source electrode and drain electrode: 3 μm). After a reversal bake process, the entire surface was exposed and developed with TMAH. A 150 nm thick Ti layer was formed on the patterned resist-coated substrate under the following sputtering conditions: Substrate temperature: 25° C. Ultimate pressure: 8.5×10 －５ Pa Atmospheric gas: Ar Sputtering pressure (total pressure): 0.4 Pa Input voltage: DC 100 W Distance between S (substrate) and T (target): 70 mm Thereafter, the substrate on which the Ti layer was formed was lifted off in acetone to pattern the ohmic electrode layer.

[0215] Finally, the resultant was annealed in air at 200° C. for 1 hour, thereby obtaining an element (etch stopper type (ES type) TFT).

[0216] (Examples 10 to 23) Sintered bodies were produced in the same manner as in Example 1 from gallium oxide powder, aluminum oxide powder, and indium oxide powder having the charged composition ratios (mass %) shown in Tables 10 to 13, and the resulting sintered bodies were used to obtain sputtering targets. Except for this, sputtering targets, oxide thin films, and TFT elements were obtained in the same manner as in Example 1.

[0217] (Comparative Example 8, Comparative Example 12 to Comparative Example 23) A sintered body was produced in the same manner as in Comparative Example 1 from gallium oxide powder, aluminum oxide powder, and indium oxide powder having the charged composition ratios (mass %) shown in Tables 14 to 16, and the resulting sintered body was used to obtain a sputtering target. Except for this, a sputtering target, an oxide thin film, and a TFT element were obtained in the same manner as in Example 1.

[0218] [4] Presence or absence of patterning defects After etching the oxide semiconductor layer with oxalic acid during the fabrication of TFT elements, the substrate with the patterned oxide thin film after peeling off the photoresist was observed with an optical microscope. A state in which the oxide thin film remained wider than the photomask pattern when viewed from above was judged to be patterning defects. Patterning defects occurred in Comparative Examples 12, 16, 17, and 18, but did not occur under the other TFT fabrication conditions, resulting in good pattern shapes.

[0219] [5] State of Oxide Thin Film (Semiconductor Film) After Fabrication of TFT (5-1) Method for Measuring the Crystalline State of the Cross Section of the Oxide Thin Film by Cross-Sectional TEM The crystalline state of the cross section of the oxide thin film in the TFT element was measured by pretreating the oxide thin film using a focused ion beam (FIB) and observing the cross section of the pretreated oxide thin film using a transmission electron microscope (TEM). Specifically, an ion beam was first applied perpendicularly to the film surface of the patterned area of ​​the oxide semiconductor film of the TFT element using an FIB (Hitachi High-Technologies Corporation "FB2100" model) to sample a test piece measuring 16 μm × 4 μm. Then, two samples were extracted from the sampled test piece in a 3 μm region extending from the edge of the region where the source electrode or drain electrode overlaps with the oxide thin film toward the non-overlapping region in the channel length direction. The two extracted samples were subjected to Ar ion milling until the thickness of the flakes in the channel width direction perpendicular to the channel length and film thickness directions was approximately 100 nm, thereby thinning the thickness of the two extracted samples. When crystal grains could not be confirmed due to ion sputter damage during FIB processing, etching was repeatedly performed using Ar ion milling (Gatan "Model 691") with an ion gun voltage of 4 keV until crystal grains could be confirmed. Cross-sectional TEM images were observed using a transmission electron microscope (JEOL "JEM-2800") at an acceleration voltage of 200 kV, at magnifications of 200,000x (approximately 4 μm square area), 500,000x (approximately 800 nm square area), 2,000,000x (approximately 200 nm square area), and 10,000,000x (approximately 40 nm square area). When the atoms were not arranged periodically in the observed image, the film was judged to be amorphous. When the atoms were arranged periodically, the grain boundaries of the oxide thin film were continuously connected from the bottom surface to the surface, and the average grain boundary angle θ between the bottom surface of the oxide thin film and the grain boundaries was 70° or more and 110° or less, the film was judged to be solid-phase crystallized.Furthermore, the crystal grain boundaries are discontinuous from the bottom surface of the oxide thin film to the surface, and the state in which the substrate side and the surface side have different crystal states was determined to be two-layer crystallization.

[0220] Tables 7 to 16 show the crystalline state of the cross section of the oxide thin film in the TFT device fabricated under each condition. While Examples 1 to 23 and Comparative Examples 8, 13, 19, 20, and 21 were solid-phase crystallized, Comparative Examples 14, 15, 22, and 23 were amorphous. Regarding the optical reliability of the die(0 0) TFT device in Comparative Examples 14 and 15, ΔVth was significantly shifted to <−5.0 V, indicating poor optical reliability. Furthermore, Comparative Examples 22 and 23 showed a significant positive shift of Vth > 2 V, resulting in a significant decrease in linear mobility. Comparative Examples 12, 16, 17, and 18 ultimately showed bilayer crystallization, but residue was generated during semiconductor patterning during TFT fabrication, making it impossible to process the oxide thin film into a TFT shape, making TFT fabrication and measurement impossible.

[0221] [6] Characteristic Evaluation of ES-Type TFTs (6-1) Initial Characteristics The obtained TFTs were measured at room temperature in a light-shielded environment (inside a shielded box) using a semiconductor parameter analyzer (Agilent Technologies, "B1500"). A drain voltage (Vd) of 0.1 V was applied. The Id-Vg characteristics were obtained by measuring the current value Id for each Vd applied, with the gate voltage (Vg) varying from -5 V to 20 V in 0.2 V steps. The calculation method for each parameter is as follows:

[0222] (a) Linear mobility (μlin) The maximum value of linear mobility when Vd = 0.1 V was determined by creating a graph of Id-Vg characteristics, calculating the transconductance (Gm) for each Vg, and deriving the linear mobility (μlin) using the equation for the linear region. Specifically, Gm was calculated by ∂(Id) / ∂(Vg). Furthermore, μlin was calculated using equation (b) for the linear region. μlin = (Gm L) / (W Ci Vd) ... (b) In equation (b), Ci is the capacitance of the gate insulating film, and is calculated based on the gate insulating film thickness of the final shape of 100 nm and SiO ２The relative dielectric constant of 3.9 and the dielectric constant of vacuum is 8.85 x 10 －１４ Ci [F / cm] calculated based on [F / cm] ２ In formula (b), L is the channel length (L length), and W is the channel width (W length).

[0223] (b) Threshold voltage (Vth) The threshold voltage (Vth) was determined by applying Vd=0.1 V and measuring the Id-Vg characteristics. From the graph of the transfer characteristics Id-Vg, －９ Vg at A was defined.

[0224] For the die (0 0) TFT elements fabricated under each condition, various parameters calculated from the Id-Vg characteristics are shown in Tables 7 to 16. Regarding linear mobility, Examples 1 to 23, Comparative Examples 8, 13, 14, and 15 had a linear mobility of 25 cm ２ / Vs or more, which is a sufficient value for high-resolution display applications, whereas Comparative Examples 19 to 23 have a linear mobility of 20 cm ２ / Vs or less, which was a low value. Furthermore, Vth was in the range of −2 V to 2 V in Examples 1 to 23, Comparative Example 8, Comparative Example 19, and Comparative Example 20, and was a value that could be corrected by a correction circuit when incorporated as a TFT in a panel. On the other hand, under the conditions of Comparative Example 21, Comparative Example 22, Comparative Example 23, Comparative Example 13, Comparative Example 14, and Comparative Example 15, Vth was >2.0 V, which was a value that could not be controlled by a correction circuit.

[0225] (6-2) Optical Reliability The substrate temperature was heated to 60°C for each TFT element, and Vd = 0.1 V was applied to measure the Id-Vg characteristics. The Vth at this time was defined as the Vth before the test. Next, Vg = -20 V was applied, and white LED light with a brightness of 4200 nits was applied from the top surface of the TFT substrate using an LED backlight unit manufactured by Asahi Spectroscopy Corporation. The threshold voltage (Vth) after 10,000 seconds was compared with that before the test, and the difference was defined as ΔVth. The evaluation results of ΔVth as optical reliability for the TFT elements of die (0 0) and die (0 -5) fabricated under each condition are shown in Tables 7 to 16. In the die(0 0) TFT elements, ΔVth was a good value of ≧−2.0 V in Examples 1 to 23, whereas ΔVth was ≦−2.2 V, indicating significant degradation, in Comparative Examples 8, 13, 14, and 15. Furthermore, in the die(0 −5) TFT elements, ΔVth was ≧−6.0 V in Examples 1 to 23, whereas ΔVth was ≦−8.0 V in Comparative Examples 8, 13, 14, and 15, indicating significant degradation.

[0226]

[0227]

[0228]

[0229]

[0230]

[0231]

[0232]

[0233]

[0234]

[0235]

[0236] 1: oxide sintered body, 1A: oxide sintered body, 1B: oxide sintered body, 1C: oxide sintered body, 3: backing plate, 20: silicon wafer, 30: gate insulating film, 40: oxide thin film, 50: source electrode, 60: drain electrode, 70: interlayer insulating film, 70A: interlayer insulating film, 70B: interlayer insulating film, 81: glass substrate, 83: oxide thin film, 85: SiO ２ film, 100: thin film transistor, 100A: thin film transistor, 11: channel layer (crystalline oxide thin film), 11A-1: first low resistance region, 11B: semiconductor region, 11A-2: second low resistance region, 21: substrate, 22: buffer layer, 24: gate insulating film, 25: gate electrode, 26: interlayer insulating film, 27: source electrode, 28: drain electrode, 29: protective film, 100B: thin film transistor, 100C: thin film transistor, 300: substrate, 301: pixel section, 302: first scanning line driving circuit, 303: second scanning line driving circuit, 304: signal line driving circuit, 310: capacitance wiring, 312: gate wiring, 313: gate wiring, 314: drain electrode, 316: transistor, 317: transistor, 318: first liquid crystal element, 319: second liquid crystal element 320: pixel section, 321: switching transistor, 322: driving transistor, 3002: photodiode, 3004: transfer transistor, 3006: reset transistor, 3008: amplification transistor, 3010: signal charge storage section, 3100: power supply line, 3110: reset power supply line, 3120: vertical output line, 501: quantum tunnel field effect transistor, 501A: quantum tunnel field effect transistor, 503: p-type semiconductor layer, 505: silicon oxide layer, 505A: insulating film, 505B: contact hole, 507: n-type semiconductor layer, 509: gate insulating film, 511: gate electrode, 513: source electrode, 515: drain electrode, 519: interlayer insulating film, 519A: contact hole, 519B: contact hole.

Claims

1. A sintered body of an oxide containing In, Ga, and Al elements, The atomic composition ratio of the In element and the Al element satisfies the following formula (1) and the following formula (2): Sintered body. [In] / ([In]+[Ga]+[Al])>0.70...(1) [Al] / ([In]+[Ga]+[Al])>0.01...(2)

2. In a field of view when the sintered body is observed with a scanning electron microscope, the area ratio of pores to the area of ​​the field of view is 0.1% or less. The sintered body according to claim 1 .

3. When the atomic composition ratio of the Ga element expressed by {[Ga] / ([In]+[Ga]+[Al])}×100 is x and the atomic composition ratio of the Al element expressed by {[Al] / ([In]+[Ga]+[Al])}×100 is y, the x and y are within composition ranges, in atomic %, surrounded by the straight lines of the following (A1), (B0), (C1), (D1), and (E1): The sintered body according to claim 1 or 2. x≧4・・・(A1) x≦22.5 (B0) y>1...(C1) 6x+14y-98≧0 (D1) 4x+20y-180≦0...(E1)

4. The x and y are within the composition ranges, in atomic %, surrounded by the straight lines of the following (A2), (B2), (C1), (D1), and (E1); The sintered body according to claim 3. x≧8...(A2) x≦20...(B2)

5. It comprises a bixbyite structure containing an In element and a crystal structure belonging to either a P1 or P-1 space group, The crystal structure belonging to P1 is represented by the following crystal structure parameter (X), and the crystal structure belonging to P-1 is represented by the following crystal structure parameter (Y): The sintered body according to claim 1 or 2. Crystal structure parameters (X): The lattice constant is a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α＝１１１．７０±０．５０°、 β=107.70±0.50°, and γ = 90.00 ± 0.50°, The crystal system is triclinic, The metals in the following atomic configuration of the space group P1 are any one of In, Ga, and Al, or any two or more of In, Ga, and Al, sharing the same atomic coordinates at a certain ratio, The atomic coordinates where the metal is located are: x±0.01, y±0.01, Including a width of z±0.01, The atomic coordinates where oxygen is located are: x±0.01, y±0.01, Includes a range of z±0.

01. Atomic species: metal, atomic coordinates (x=0.04, y=0.36, z=0.87) Atomic species: metal, atomic coordinates (x=0.13, y=0.12, z=0.62) Atomic species: metal, atomic coordinates (x=0.21, y=0.85, z=0.39) Atomic species: metal, atomic coordinates (x=0.23, y=0.11, z=0.97) Atomic species: metal, atomic coordinates (x=0.29, y=0.64, z=0.11) Atomic species: metal, atomic coordinates (x=0.46, y=0.12, z=0.63) Atomic species: metal, atomic coordinates (x=0.58, y=0.14, z=0.01) Atomic species: metal, atomic coordinates (x=0.62, y=0.64, z=0.11) Atomic species: metal, atomic coordinates (x=0.69, y=0.18, z=0.32) Atomic species: metal, atomic coordinates (x=0.09, y=0.88, z=0.03) Atomic species: metal, atomic coordinates (x=0.02, y=0.13, z=0.30) Atomic species: metal, atomic coordinates (x=0.06, y=0.61, z=0.46) Atomic species: metal, atomic coordinates (x=0.15, y=0.40, z=0.19) Atomic species: metal, atomic coordinates (x=0.26, y=0.36, z=0.54) Atomic species: metal, atomic coordinates (x=0.34, y=0.13, z=0.30) Atomic species: metal, atomic coordinates (x=0.41, y=0.61, z=0.45) Atomic species: metal, atomic coordinates (x=0.48, y=0.40, z=0.23) Atomic species: metal, atomic coordinates (x=0.84, y=0.39, z=0.23) Atomic species: metal, atomic coordinates (x=0.96, y=0.64, z=0.13) Atomic species: metal, atomic coordinates (x=0.87, y=0.88, z=0.38) Atomic species: metal, atomic coordinates (x=0.79, y=0.15, z=0.61) Atomic species: metal, atomic coordinates (x=0.77, y=0.89, z=0.03) Atomic species: metal, atomic coordinates (x=0.71, y=0.36, z=0.89) Atomic species: metal, atomic coordinates (x=0.54, y=0.88, z=0.37) Atomic species: metal, atomic coordinates (x=0.42, y=0.86, z=0.99) Atomic species: metal, atomic coordinates (x=0.38, y=0.36, z=0.89) Atomic species: metal, atomic coordinates (x=0.31, y=0.82, z=0.68) Atomic species: metal, atomic coordinates (x=0.91, y=0.12, z=0.97) Atomic species: metal, atomic coordinates (x=0.98, y=0.87, z=0.70) Atomic species: metal, atomic coordinates (x=0.94, y=0.39, z=0.54) Atomic species: metal, atomic coordinates (x=0.85, y=0.60, z=0.81) Atomic species: metal, atomic coordinates (x=0.74, y=0.64, z=0.46) Atomic species: metal, atomic coordinates (x=0.66, y=0.87, z=0.70) Atomic species: metal, atomic coordinates (x=0.59, y=0.39, z=0.55) Atomic species: metal, atomic coordinates (x=0.52, y=0.60, z=0.77) Atomic species: metal, atomic coordinates (x=0.16, y=0.61, z=0.77) Atomic species: oxygen, atomic coordinates (x = 0.02, y = 0.73, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.03, y = 0.45, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.05, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.74, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.23, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.51, z = 0.09) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.13, y = 0.79, z = 0.17) Atomic species: oxygen, atomic coordinates (x = 0.19, y = 0.21, z = 0.84) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.23, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.25, y = 0.66, z = 0.49) Atomic species: oxygen, atomic coordinates (x = 0.27, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.30, y = 0.26, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.33, y = 0.44, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.39, y = 0.73, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.41, y = 0.24, z = 0.07) Atomic species: oxygen, atomic coordinates (x = 0.43, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.46, y = 0.51, z = 0.11) Atomic species: oxygen, atomic coordinates (x = 0.47, y = 0.79, z = 0.15) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.25, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.64, y = 0.03, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.66, y = 0.34, z = 0.23) Atomic species: oxygen, atomic coordinates (x = 0.72, y = 0.03, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.78, y = 0.51, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.25, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.96, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.98, y = 0.27, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.97, y = 0.55, z = 0.72) Atomic species: oxygen, atomic coordinates (x = 0.95, y = 0.98, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.90, y = 0.26, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.90, y = 0.77, z = 0.94) Atomic species: oxygen, atomic coordinates (x = 0.88, y = 0.49, z = 0.91) Atomic species: oxygen, atomic coordinates (x = 0.88, y = 0.53, z = 0.43) Atomic species: oxygen, atomic coordinates (x = 0.87, y = 0.21, z = 0.83) Atomic species: oxygen, atomic coordinates (x = 0.81, y = 0.79, z = 0.16) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.77, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.75, y = 0.34, z = 0.51) Atomic species: oxygen, atomic coordinates (x = 0.73, y = 0.98, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.70, y = 0.74, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.67, y = 0.56, z = 0.71) Atomic species: oxygen, atomic coordinates (x = 0.62, y = 0.98, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.61, y = 0.27, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.59, y = 0.76, z = 0.93) Atomic species: oxygen, atomic coordinates (x = 0.58, y = 0.53, z = 0.43) Atomic species: oxygen, atomic coordinates (x = 0.54, y = 0.49, z = 0.89) Atomic species: oxygen, atomic coordinates (x = 0.53, y = 0.21, z = 0.85) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.75, z = 0.64) Atomic species: oxygen, atomic coordinates (x = 0.36, y = 0.97, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.34, y = 0.66, z = 0.77) Atomic species: oxygen, atomic coordinates (x = 0.28, y = 0.97, z = 0.60) Atomic species: oxygen, atomic coordinates (x = 0.22, y = 0.49, z = 0.88) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.75, z = 0.94) Atomic species: oxygen, atomic coordinates (x = 0.04, y = 0.98, z = 0.88) Crystal structure parameters (Y): The lattice constant is a = 10.07 ± 0.15 Å, b = 10.45 ± 0.15 Å, c = 11.01 ± 0.15 Å, α＝１１１．７０±０．５０°、 β=107.70±0.50°, and γ = 90.00 ± 0.50°, The crystal system is triclinic, The metals in the following atomic configuration of the space group P-1 are in a state where any one of In, Ga, and Al, or any two or more of In, Ga, and Al share the same atomic coordinates at a certain ratio, The atomic coordinates where the metal is located are: x±0.01, y±0.01, Including a width of z±0.01, The atomic coordinates where oxygen is located are: x±0.01, y±0.01, Includes a range of z±0.

01. Atomic species: metal, atomic coordinates (x=0.04, y=0.36, z=0.87) Atomic species: metal, atomic coordinates (x=0.13, y=0.12, z=0.62) Atomic species: metal, atomic coordinates (x=0.21, y=0.85, z=0.39) Atomic species: metal, atomic coordinates (x=0.23, y=0.11, z=0.97) Atomic species: metal, atomic coordinates (x=0.29, y=0.64, z=0.11) Atomic species: metal, atomic coordinates (x=0.46, y=0.12, z=0.63) Atomic species: metal, atomic coordinates (x=0.58, y=0.14, z=0.01) Atomic species: metal, atomic coordinates (x=0.62, y=0.64, z=0.11) Atomic species: metal, atomic coordinates (x=0.69, y=0.18, z=0.32) Atomic species: metal, atomic coordinates (x=0.09, y=0.88, z=0.03) Atomic species: metal, atomic coordinates (x=0.02, y=0.13, z=0.30) Atomic species: metal, atomic coordinates (x=0.06, y=0.61, z=0.46) Atomic species: metal, atomic coordinates (x=0.15, y=0.40, z=0.19) Atomic species: metal, atomic coordinates (x=0.26, y=0.36, z=0.54) Atomic species: metal, atomic coordinates (x=0.34, y=0.13, z=0.30) Atomic species: metal, atomic coordinates (x=0.41, y=0.61, z=0.45) Atomic species: metal, atomic coordinates (x=0.48, y=0.40, z=0.23) Atomic species: metal, atomic coordinates (x=0.84, y=0.39, z=0.23) Atomic species: oxygen, atomic coordinates (x = 0.02, y = 0.73, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.03, y = 0.45, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.05, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.74, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.10, y = 0.23, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.51, z = 0.09) Atomic species: oxygen, atomic coordinates (x = 0.12, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.13, y = 0.79, z = 0.17) Atomic species: oxygen, atomic coordinates (x = 0.19, y = 0.21, z = 0.84) Atomic species: oxygen, atomic coordinates (x = 0.20, y = 0.23, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.25, y = 0.66, z = 0.49) Atomic species: oxygen, atomic coordinates (x = 0.27, y = 0.02, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.30, y = 0.26, z = 0.65) Atomic species: oxygen, atomic coordinates (x = 0.33, y = 0.44, z = 0.29) Atomic species: oxygen, atomic coordinates (x = 0.38, y = 0.02, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.39, y = 0.73, z = 0.35) Atomic species: oxygen, atomic coordinates (x = 0.41, y = 0.24, z = 0.07) Atomic species: oxygen, atomic coordinates (x = 0.43, y = 0.47, z = 0.57) Atomic species: oxygen, atomic coordinates (x = 0.46, y = 0.51, z = 0.11) Atomic species: oxygen, atomic coordinates (x = 0.47, y = 0.79, z = 0.15) Atomic species: oxygen, atomic coordinates (x = 0.50, y = 0.25, z = 0.36) Atomic species: oxygen, atomic coordinates (x = 0.64, y = 0.03, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.66, y = 0.34, z = 0.23) Atomic species: oxygen, atomic coordinates (x = 0.72, y = 0.03, z = 0.40) Atomic species: oxygen, atomic coordinates (x = 0.78, y = 0.51, z = 0.12) Atomic species: oxygen, atomic coordinates (x = 0.80, y = 0.25, z = 0.06) Atomic species: oxygen, atomic coordinates (x = 0.96, y = 0.02, z = 0.12)

6. When the weight ratios of the bixbyite structure containing In, the crystal structure belonging to the space group P1 or P-1, and other crystal structures are calculated by performing Rietveld analysis on the spectrum obtained by performing X-ray diffraction measurement on the sintered body, the weight ratio of the bixbyite structure crystal containing In to the crystal of the entire sintered body is 70% or more. The sintered body according to claim 5.

7. The sintered body contains H element, and the atomic concentration of the H element contained in the sintered body is 1×10 １６ cm －３ That's it, 1 x 10 １８ cm －３ is less than The sintered body according to claim 1 or 2.

8. The sintered body contains a C element, and the atomic concentration of the C element contained in the sintered body is 1×10 １６ cm －３ That's it, 1 x 10 １８ cm －３ is less than The sintered body according to claim 1 or 2.

9. The bending strength is 190 MPa or more. The sintered body according to claim 1 or 2.

10. A sputtering target using the oxide sintered body according to claim 1 or 2.

11. An oxide thin film formed using the sputtering target according to claim 10.

12. A thin film transistor comprising the oxide thin film of claim 11.

13. An electronic device comprising the thin film transistor according to claim 12.

14. A method for producing a sintered body of an oxide containing In, Ga, and Al elements, comprising: A step of mixing and crushing indium oxide, gallium oxide, and aluminum oxide using a bead mill, granulating the mixture by a spray drying method to obtain a granulated powder, and then classifying the granulated powder; a molding step of molding the classified granulated powder to obtain a molded body; a sintering step of sintering the compact, The atomic composition ratio of In element and Al element of the sintered body satisfies the following formula (1) and the following formula (2): A method for manufacturing a sintered body. [In] / ([In]+[Ga]+[Al])>0.70...(1) [Al] / ([In]+[Ga]+[Al])>0.01...(2)