THIN FILM TRANSISTOR USING BORON-DOPED OXIDE SEMICONDUCTOR THIN FILM AND METHOD OF FABRICATING THE SAME

• US 20100155716A1
• Filed: 09/16/2009
• Published: 06/24/2010
• Est. Priority Date: 12/18/2008
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: CHUNG, Sung Mook, HWANG, Chi Sun, CHU, Hye Yong, CHEONG, Woo Seok, RYU, Min Ki
• Granted Patent: US 8,071,434 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 21/0237 Materials
• 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 21/02573 Conductivity type
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• 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

Provided are a thin film transistor, to which a boron-doped oxide semiconductor thin film is applied as a channel layer, and a method of fabricating the same. The thin film transistor includes source and drain electrodes, a channel layer, a gate insulating layer, and a gate electrode, which are formed on a substrate. The channel layer is an oxide semiconductor thin film doped with boron. Therefore, it is possible to remarkably improve electrical characteristics and high temperature stability of the thin film transistor.

Claims

1. A thin film transistor comprising:

source and drain electrodes, a channel layer, a gate insulating layer, and a gate electrode, which are formed on a substrate,

wherein the channel layer is an oxide semiconductor thin film doped with boron.

2. The thin film transistor according to claim 1, further comprising a channel protection layer formed on the channel layer and formed of at least one insulating material selected from the group consisting of AlOx, SiNx and SiOx.

3. The thin film transistor according to claim 1, wherein the thin film transistor has:

a top-gate coplanar structure in which source and drain electrodes, a gate insulating layer and a gate electrode are sequentially formed on a substrate;

a top-gate staggered structure in which a channel layer, source and drain electrodes, a gate insulating layer and a gate electrode are sequentially formed on a substrate;

a bottom-gate coplanar structure in which a gate electrode, a gate insulating layer, source and drain electrodes, and a channel layer are sequentially formed on a substrate;

or a bottom-gate staggered structure in which a gate electrode, a gate insulating layer, a channel layer, and source and drain electrodes are sequentially formed on a substrate.

4. The thin film transistor according to claim 1, wherein the oxide semiconductor is formed of at least one selected from the group consisting of ZnO, In—

Zn—

O, Zn—

Sn—

O, In—

Ga—

ZnO, Zn—

In—

Sn—

O, In—

Ga—

O, and SnO₂.

5. The thin film transistor according to claim 2, wherein the oxide semiconductor is formed of at least one selected from the group consisting of ZnO, In—

Zn—

O, Zn—

Sn—

O, In—

Ga—

ZnO, Zn—

In—

Sn—

O, In—

Ga—

O, and SnO₂.

6. The thin film transistor according to claim 1, wherein the amount of the boron doped on the oxide semiconductor is 0.001 to 10 at % of the total atomic weight of a metal atom of a metal oxide constituting the oxide semiconductor.

7. The thin film transistor according to claim 2, wherein the amount of the boron doped on the oxide semiconductor is 0.001 to 10 at % of the total atomic weight of a metal atom of a metal oxide constituting the oxide semiconductor.

8. The thin film transistor according to claim 1, wherein the gate insulating layer is formed of at least one insulating material selected from the group consisting of AlOx, SiNx and SiOx.

9. The thin film transistor according to claim 2, wherein the gate insulating layer is formed of at least one insulating material selected from the group consisting of AlOx, SiNx and SiOx.

10. A method of fabricating a thin film transistor in which source and drain electrodes, a channel layer, a gate insulating layer, and a gate electrode are formed on a substrate, the method comprising:

forming a channel layer using an oxide semiconductor doped with boron; and

patterning the channel layer.

11. The method according to claim 10, further comprising forming a channel protection layer on the channel layer using an insulating material, wherein the channel protection layer is patterned together with the channel layer.

12. The method according to claim 10, wherein, in forming the channel layer, the oxide semiconductor is formed of at least one selected from the group consisting of ZnO, In—

Zn—

O, Zn—

Sn—

O, In—

Ga—

ZnO, Zn—

In—

Sn—

O, In—

Ga—

O, and SnO₂, and the amount of the boron doped on the oxide semiconductor is 0.001 to 10 at % of the total atomic weight of a metal atom of a metal oxide constituting the oxide semiconductor.

13. The method according to claim 11, wherein, in forming the channel layer, the oxide semiconductor is formed of at least one selected from the group consisting of ZnO, In—

Zn—

O, Zn—

Sn—

O, In—

Ga—

ZnO, Zn—

In—

Sn—

O, In—

Ga—

O, and SnO₂, and the amount of the boron doped on the oxide semiconductor is 0.001 to 10 at % of the total atomic weight of a metal atom of a metal oxide constituting the oxide semiconductor.

14. The method according to claim 10, wherein the channel layer is formed by sputtering, pulse laser deposition (PLD) or ion-beam deposition.

15. The method according to claim 11, wherein the channel layer is formed by sputtering, pulse laser deposition (PLD) or ion-beam deposition.

16. The method according to claim 11, wherein, in forming the channel protection layer, the channel protection layer is formed to a thickness of about 1 to about 20 nm by chemical vapor deposition (CVD), atomic layer deposition (ALD), or sputtering using at least one insulating material selected from the group consisting of AlOx, SiNx, and SiOx.

17. The method according to claim 10, wherein the channel layer is patterned using photoresist, and etched by dry etching, wet etching, or ion milling.

18. The method according to claim 11, wherein the channel layer and the channel protection layer are patterned using photoresist, and etched by dry etching, wet etching, or ion milling.

19. The method according to claim 10, wherein patterning the channel layer is performed by forming a lift-off pattern using photoresist, and the photoresist is applied at a temperature of less than 150°

C.

20. The method according to claim 11, wherein patterning the channel layer and the channel protection layer are performed by forming a lift-off pattern using photoresist, and the photoresist is applied at a temperature of less than 150°

C.