# US 11,443,943 B2 · Sputtering target, oxide semiconductor thin film, and method for producing these

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- Number: US 11,443,943 B2
- Document ID: US11443943B2
- Status: Granted
- Kind: B2
- Application number: 16/211,211
- Filed: 2018-12-05
- Published: 2019-04-11
- Granted: 2022-09-13
- Earliest claimed: 2012-11-14
- Assignees: Idemitsu Kosam Co., Ltd.
- Applicants: Idemitsu Kosan Co., Ltd.
- Inventors: Kazuaki Ebata; Nozomi Tajima
- Web page: https://patentgrep.com/patent/US11443943B2

## CPC

- H10P 14/3426: {Oxides}
- C04B 35/01: based on oxide ceramics
- C04B 35/453: based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
- C23C 14/08: Oxides (C23C14/10 takes precedence)
- C23C 14/3414: {Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy}
- C23C 14/352: {using more than one target (C23C14/56 takes precedence)}
- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 62/86: being Group II-VI materials, e.g. ZnO
- H10D 99/00: Subject matter not provided for in other groups of this subclass
- H10P 14/22: using physical deposition, e.g. vacuum deposition or sputtering
- H10P 14/3434: {being oxide semiconductor materials (Group IIB-VIA semiconductor materials H10P14/3424)}
- C04B 2235/3217: Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
- C04B 2235/3284: Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
- C04B 2235/3286: Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
- C04B 2235/3293: Tin oxides, stannates or oxide forming salts thereof, e.g. indium tin oxide [ITO]
- C04B 2235/5445: submicron sized, i.e. from 0,1 to 1 micron
- C04B 2235/6562: Heating rate
- C04B 2235/6565: Cooling rate
- C04B 2235/6567: Treatment time
- C04B 2235/77: Density
- C04B 2235/80: Phases present in the sintered or melt-cast ceramic products other than the main phase
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A sputtering target including an oxide that includes an indium (In) element, a tin (Sn) element, a zinc (Zn) element and an aluminum (Al) element, wherein the oxide includes a homologous structure compound represented by InAlO3(ZnO)m (m is 0.1 to 10) and a bixbyite structure compound represented by In2O3.

## Claims

### Claim 1

An oxide semiconductor thin film formed by a sputtering method with the use of a sputtering target comprising an oxide that comprises an indium (In) element, a tin (Sn) element, a zinc (Zn) element and an aluminum (Al) element
wherein the atomic ratio of In, Sn, Zn and Al satisfies the following formulas (1) to (4):
0.50≤In/(In+Sn+Zn+Al)≤0.75 (1)
0.01≤Sn/(In+Sn+Zn+Al)≤0.30 (2)
0.10≤Zn/(In+Sn+Zn+Al)≤0.70 (3)
0.01≤Al/(In+Sn+Zn+Al)≤0.40 (4)
and wherein in the formulas, In, Sn, Zn and Al independently indicate an atomic ratio of each element in the sputtering target.

### Claim 2

A method for producing an oxide semiconductor thin film, wherein the film is formed by a sputtering method with the use of sputtering target in an atmosphere of a mixed gas that comprises: one or more selected from water vapor, an oxygen gas and a nitrous oxide gas and further comprises a rare gas;
wherein the sputtering target comprises an oxide that comprises an indium (In) element, a tin (Sn) element, a zinc (Zn) element and an aluminum (Al) element
wherein the atomic ratio of In, Sn, Zn and Al satisfies the following formulas (1) to (4):
0.50≤In/(In+Sn+Zn+Al)≤0.75 (1)
0.01≤Sn/(In+Sn+Zn+Al)≤0.30 (2)
0.10≤Zn/(In+Sn+Zn+Al)≤0.70 (3)
0.01≤Al/(In+Sn+Zn+Al)≤0.40 (4)
and wherein in the formulas, In, Sn, Zn and Al independently indicate an atomic ratio of each element in the sputtering target.

### Claim 3 (depends on 2)

The method for producing an oxide semiconductor thin film according to claim 2, wherein the formation of the oxide semiconductor thin film is conducted in an atmosphere of a mixed gas that comprises a rare gas and at least water vapor.

### Claim 4 (depends on 3)

The method for producing an oxide semiconductor thin film according to claim 3, wherein the ratio of the water vapor contained in the mixed gas is 0.1% to 25% in terms of a partial pressure ratio.

### Claim 5 (depends on 2)

The method for producing the oxide semiconductor thin film according to claim 2 comprising:
transporting substrates in sequence to positions opposing to 3 or more of the sputtering targets of claim 2 arranged in parallel with a prescribed interval in a vacuum chamber;
applying a negative potential and a positive potential alternately from an AC power source to each of the targets; and
causing plasma to be generated on the target by applying at least one output from the AC power source while switching the target to which a potential is applied among two or more of the sputtering targets that are divergently connected to this AC power source, thereby forming a film on a substrate surface.

### Claim 6 (depends on 5)

The method for producing an oxide semiconductor thin film according to claim 5, wherein the AC power density of the AC power source is 3 W/cm2 or more and 20 W/cm2 or less.

### Claim 7 (depends on 5)

The method for producing an oxide semiconductor thin film according to claim 5, wherein the frequency of the AC power source is 10 kHz to 1 MHz.

### Claim 8 (depends on 2)

A thin film transistor comprising, as a channel layer, the oxide semiconductor thin film formed by the method for producing an oxide semiconductor thin film according to claim 2.

### Claim 9 (depends on 8)

The thin film transistor according to claim 8 that has a field effect mobility of 10 cm2/Vs or more.