Field effect transistor

• US 7,868,326 B2
• Filed: 11/09/2005
• Issued: 01/11/2011
• Est. Priority Date: 11/10/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.), Japan Science & Technology Trading Co. Limited, Tokyo Institute of Technology (National University Corporation Tokyo Institute of Technology)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.), Tokyo Institute of Technology (National University Corporation Tokyo Institute of Technology)
• Inventors: Sano, Masafumi, Nakagawa, Katsumi, Kamiya, Toshio, Nomura, Kenji, Hosono, Hideo
• Primary Examiner(s): Fahmy; Wael M
• Assistant Examiner(s): Yang; Minchul
• Application Number:
  US11/269,647
• Publication Number:
  US 20060113539A1
• Time in Patent Office: 1,889 Days
• Field of Search: 257/43, 257/57, 257/52, 257/55, 257/56, 257/58, 257/59, 257/62, 257/72, 257/E29.083, 257/E29.092, 257/E29.101
• US Class Current: 257/58
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• 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 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/51 Insulating materials associated therewith for MIS structures on thin film semiconductor H01L29/4908
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous

Abstract

A novel field-effect transistor is provided which employs an amorphous oxide. In an embodiment of the present invention, the transistor comprises an amorphous oxide layer containing electron carrier at a concentration less than 1×10⁻¹⁸/cm³, and the gate-insulating layer is comprised of a first layer being in contact with the amorphous oxide and a second layer different from the first layer.

Claims

1. A field-effect transistor provided with a source electrode, a drain electrode, a gate insulator, a gate electrode, and a transparent channel layer, wherein

the channel layer comprises an amorphous oxide of a compound having

(a) a composition when in crystalline state represented by In₂₋

xM3_xO₃(Zn<sub>1−

y</sub>M2_yO)_m, wherein M2 is Mg or Ca;

M3 is B, Al, Ga or Y;

0≦

x ≦

2;

0≦

y ≦

1; and

m is zero or a natural number less than 6, or a mixture of said compounds;

(b) an electric carrier concentration of 10¹²/cm³ or more and less than 10¹⁸/cm³, wherein an electron mobility of the channel layer tends to increase with increase of the electron carrier concentration; and

(c) controlled oxygen defect density resulting from subjecting the amorphous oxide to treatment in an atmosphere containing oxygen at a predetermined pressure upon or after film formation; and

at least one of the source electrode, the drain electrode and the gate electrode is transparent to visible light, wherein current between the drain electrode and the source electrode when no gate voltage is applied is less than 10 microamperes.

2. The field effect transistor according to claim 1, which has a metal wiring connected to at least one of the source electrode, the drain electrode and the gate electrode.

3. The field effect transistor according to claim 1, wherein the amorphous oxide is an oxide containing at least one of In, Zn, and Sn, or an oxide containing In, Zn, and Ga.

4. The field-effect transistor according to claim 1, wherein a metal wiring is connected to an electrode transparent to light which belongs to the source electrode, the drain electrode or the gate electrode.

5. The field-effect transistor according to claim 1, wherein the amorphous oxide is any one selected from the group consisting of an oxide containing In, Zn and Sn;

an oxide containing In and Zn;

an oxide containing In and Sn; and

an oxide containing In.

6. A field effect transistor provided with a source electrode, a drain electrode, a gate insulator, a gate electrode, and a transparent channel layer, wherein

the channel layer comprises an amorphous oxide of a compound having

(a) a composition when in crystalline state represented by In₂₋

xM3_xO₃(Zn<sub>1−

y</sub>M2_yO)_m, wherein M2 is Mg or Ca;

M3 is B, Al, Ga or Y;

0≦

x ≦

2;

0≦

y ≦

1; and

m is zero or a natural number less than 6, or a mixture of said compounds;

(b) an electric carrier concentration of 10¹²/cm³ or more and less than 10¹⁸/cm³, wherein an electron mobility of the channel layer tends to increase with increase of the electron carrier concentration; and

(c) controlled oxygen defect density resulting from subjecting the amorphous oxide to treatment in an atmosphere containing oxygen at a predetermined pressure upon or after film formation; and

has a lamination structure comprised of a first layer in which at least one of the source electrode, the drain electrode and the gate electrode is transparent to visible light, and a second layer composed of a metal, or

has a lamination structure comprised of a first layer in which a wiring connected at least one of the source electrode, the drain electrode and the gate electrode is transparent to visible light, and a second layer composed of a metal, wherein current between the drain electrode and the source electrode when no gate voltage is applied is less than 10 microamperes.

7. A field effect transistor provided with a source electrode, a drain electrode, a gate insulator, a gate electrode, and a transparent channel layer, wherein

the channel layer comprises an amorphous oxide of a compound having

(a) a composition when in crystalline state represented by In₂₋

xM3_xO₃(Zn<sub>1−

y</sub>M2_yO)_m, wherein M2 is Mg or Ca;

M3 is B, Al, Ga or Y;

0≦

x ≦

2;

0≦

y ≦

1; and

m is zero or a natural number less than 6, or a mixture of said compounds;

(b) an electric carrier concentration of 10¹²/cm³ or more and less than 10¹⁸/cm³, wherein an electron mobility of the channel layer tends to increase with increase of the electron carrier concentration, and;

(c) controlled oxygen defect density resulting from subjecting the amorphous oxide to treatment in an atmosphere containing oxygen at a predetermined pressure upon or after film formation; and

the gate insulator is comprised of a first layer being in contact with the amorphous oxide and a second layer different from the first layer and is laminated on the first layer, wherein current between the drain electrode and the source electrode when no gate voltage is applied is less than 10 microamperes.

8. The field effect transistor according to claim 7, wherein the first layer is an insulating layer comprising HfO₂, Y₂O₃, or a mixed crystal compound containing HfO₂ or Y₂O₃.

9. The field effect transistor according to claim 7, wherein the amorphous oxide is an oxide containing at least one of In, Zn, and Sn, or an oxide containing In, Zn, and Ga.

10. The field effect transistor according to claim 7, wherein the first layer is an interface improvement layer for improving an interfacial property with the channel layer, and the second layer is a current leakage prevention layer for preventing leakage of electric current.

11. The field-effect transistor according to claim 7, wherein the amorphous oxide is any one selected from the group consisting of an oxide containing In, Zn and Sn;

an oxide containing In and Zn;

an oxide containing In and Sn; and

an oxide containing In.

12. A field effect transistor provided with a source electrode, a drain electrode, a gate insulator, a gate electrode, and a transparent channel layer, wherein

the channel layer comprises an amorphous oxide of a compound having

(a) a composition when in crystalline state represented by In₂₋

xM3_xO₃(Zn<sub>1−

y</sub>M2_yO)_m, wherein M2 is Mg or Ca;

M3 is B, Al, Ga or Y;

0≦

x ≦

2;

0≦

y ≦

1; and

m is zero or a natural number less than 6, or a mixture of said compounds;

(b) an electric carrier concentration of 10¹²/cm³ or more and less than 10¹⁸/cm³, wherein an electron mobility of the channel layer tends to increase with increase of the electron carrier concentration; and

(c) controlled oxygen defect density resulting from subjecting the amorphous oxide to treatment in an atmosphere containing oxygen at a predetermined pressure upon or after film formation; and

a passivation layer is provided between the channel layer and the gate insulator, wherein current between the drain electrode and the source electrode when no gate voltage is applied is less than 10 microamperes.

13. The field effect transistor according to claim 12, wherein the amorphous oxide is an oxide containing at least one of In, Zn, and Sn, or an oxide containing In, Zn, and Ga.

14. The field effect transistor according to claim 12, wherein the passivation layer is a current leakage prevention layer for preventing leakage of electric current.

15. A field effect transistor provided with a source electrode, a drain electrode, a gate insulator, a gate electrode, and a transparent channel layer on a substrate, wherein

the channel layer comprises an amorphous oxide of a compound having (a) a composition when in crystalline state represented by In₂₋

xM3_xO₃(Zn<sub>1−

y</sub>M2_yO)_m, wherein M2 is Mg or Ca;

M3 is B, Al, Ga or Y;

0≦

x ≦

2;

0≦

y ≦

1; and

m is zero or a natural number less than 6, or a mixture of said compounds;

(b) an electric carrier concentration of 10¹²/cm³ or more and less than 10¹⁸/cm³, wherein an electron mobility of the channel layer tends to increase with increase of the electron carrier concentration; and

(c) controlled oxygen defect density resulting from subjecting the amorphous oxide to treatment in an atmosphere containing oxygen at a predetermined pressure upon or after film formation; and

a surface-coating layer being provided between the channel layer and the substrate, wherein current between the drain electrode and the source electrode when no gate voltage is applied is less than 10 microamperes.

16. The field effect transistor according to claim 15, wherein the amorphous oxide is an oxide containing at least one of In, Zn, and Sn, or an oxide containing In, Zn, and Ga.

17. The field effect transistor according to claim 15, wherein the surface-coating layer is an adhesion-improvement layer for improving the adhesiveness between the substrate and the channel layer.