THIN-FILM TRANSISTOR

• US 20140084289A1
• Filed: 05/01/2012
• Published: 03/27/2014
• Est. Priority Date: 05/10/2011
• Status: Active Grant

• Current Assignee: Idemitsu Kosan Company Limited
• Original Assignee: Idemitsu Kosan Company Limited
• Inventors: Itose, Masayuki, Nishimura, Mami, Kawashima, Hirokazu, Sunagawa, Misa, Kasami, Masashi, Yano, Koki
• Granted Patent: US 9,054,196 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/40 Metallic constituents or additives not added as binding phase
• CPC Class Codes: C04B 2235/5409 expressed by specific surface values
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/6565 Cooling rate
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/6585 at an oxygen percentage above that of air
• CPC Class Codes: C04B 2235/664 Reductive annealing
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/963 Surface properties, e.g. surface roughness
• CPC Class Codes: C04B 35/01 based on oxide ceramics
• CPC Class Codes: C04B 35/453 based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
• CPC Class Codes: C04B 35/62675 characterised by the treatment temperature
• CPC Class Codes: C04B 35/6455 Hot isostatic pressing
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02631 : Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 29/26 : including, apart from doping materials or other impurities, elements provided for in two or more of the groups H01L29/16, H01L29/18, H01L29/20, H01L29/22, H01L29/24 , e.g. alloys
• CPC Class Codes: H01L 29/786 : Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• CPC Class Codes: H01L 29/7869 : having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

A thin film transistor including an active layer, and has a field-effect mobility of 25 cm²/Vs or more, the active layer being formed of an oxide that includes In, Ga, and Zn in an atomic ratio that falls within the following region 1, region 2, or region 3, the region 1 being defined by 0.58≦In/(In+Ga+Zn)≦0.68 and 0.15<Ga/(In+Ga+Zn)≦0.29, the region 2 being defined by 0.45≦In/(In+Ga+Zn)<0.58 and 0.09≦Ga/(In+Ga+Zn)<0.20, and the region 3 being defined by 0.45≦In/(In+Ga+Zn)<0.58 and 0.20≦Ga/(In+Ga+Zn)≦0.27.

Claims

1. A thin film transistor comprising an active layer, and having a field-effect mobility of 25 cm²/Vs or more, the active layer comprising an oxide that comprises In, Ga, and Zn in an atomic ratio that falls within a region 1, a region 2, or a region 3,

the region 1 being defined by:

0.58≦

In/(In+Ga+Zn)≦

0.68

0.15<

Ga/(In+Ga+Zn)≦

0.29,

the region 2 being defined by;

0.45≦

In/(In+Ga+Zn)<

0.58

0.09≦

Ga/(In+Ga+Zn)<

0.20, and

the region 3 being defined by;

0.45≦

In/(In+Ga+Zn)<

0.58

0.20≦

Ga/(In+Ga+Zn)≦

0.27.

2. The thin film transistor according to claim 1, the thin film transistor having a field-effect mobility of 30 cm²/Vs or more.

9. A method for producing the thin film transistor according to claim 1 the method comprising producing an oxide thin film using the sputtering target comprising an oxide sintered body that comprises In, Ga, and Zn in an atomic ratio that falls within a region 1, a region 2, or a region 3,

the region 1 being defined by:

0.58≦

In/(In+Ga+Zn)≦

0.68

0.15<

Ga/(In+Ga+Zn)≦

0.29,

the region 2 being defined by;

0.45≦

In/(In+Ga+Zn)<

0.58

0.09≦

Ga/(In+Ga+Zn)<

0.20, and

the region 3 being defined by;

0.45≦

In/(In+Ga+Zn)<

0.58

0.20≦

Ga/(In+Ga+Zn)≦

0.27.

3. A sputtering target comprising an oxide sintered body that comprises In, Ga, and Zn in an atomic ratio that falls within a region 1, a region 2, or a region 3,

the region 1 being defined by:

0.58≦

In/(In+Ga+Zn)≦

0.68

0.15<

Ga/(In+Ga+Zn)≦

0.29,

the region 2 being defined by;

0.45≦

In/(In+Ga+Zn)<

0.58

0.09≦

Ga/(In+Ga+Zn)<

0.20, and

the region 3 being defined by;

0.45≦

In/(In+Ga+Zn)<

0.58

0.20≦

Ga/(In+Ga+Zn)≦

0.27.

4. The sputtering target according to claim 3, wherein the oxide sintered body has a specific resistivity of less than 15 mΩ

·

cm and a relative density of more than 97%.

5. The sputtering target according to claim 3 wherein the oxide sintered body comprises In, Ga, and Zn in an atomic ratio that falls within the region 1, and comprises a compound having a homologous structure represented by (InGaO₃)ZnO and a compound having a bixbyite structure represented by In₂O₃.

6. The sputtering target according to claim 3 wherein the oxide sintered body comprises In, Ga, and Zn in an atomic ratio that falls within the region 2, and comprises an oxide for which a diffraction peak is observed by X-ray diffraction measurement (Cu—

Kα

) at an angle (2θ

) of 7.0°

to 8.4°

, 30.6°

to 32.0°

, 33.8°

to 35.8°

, 53.5°

to 56.5°

, and 56.5°

to 59.5°

.

7. The sputtering target according to claim 3 wherein the oxide sintered body comprises In, Ga, and Zn in an atomic ratio that falls within the region 3, and comprises a compound having a homologous structure represented by (InGaO₃)ZnO.

8. A method for producing the sputtering target according to claim 3, the method comprising:

heating from 400°

C. to 800°

C. at 2.5°

C./min or less;

heating from 800°

C. to a sintering temperature at 1.0°

C./min or less; and

sintering at a sintering temperature of 1300 to 1450°

C. for a sintering time of 6 to 48 hours.