Thin-film transistor structure, as well as thin-film transistor and display device each having said structure

• US 9,379,248 B2
• Filed: 04/19/2012
• Issued: 06/28/2016
• Est. Priority Date: 04/22/2011
• Status: Active Grant

• Current Assignee: Klaus Schmidt
• Original Assignee: Kobe Steel Limited
• Inventors: Maeda, Takeaki, Kugimiya, Toshihiro
• Primary Examiner(s): Wright, Tucker J
• Application Number:
  US14/113,303
• Publication Number:
  US 20140054588A1
• Time in Patent Office: 1,531 Days
• US Class Current: 1/1
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• 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
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

There is provided an oxide semiconductor layer capable of making stable the electric characteristics of a thin-film transistor without requiring an oxidatively-treated layer when depositing a passivation layer or the like in display devices such as organic EL displays depositing and liquid crystal displays. The thin-film transistor structure of the present invention at least having, on a substrate, an oxide semiconductor layer, a source-drain electrode, and a passivation layer in order from the substrate side, wherein the oxide semiconductor layer is a stacked product of a first oxide semiconductor layer and a second oxide semiconductor layer; the first oxide semiconductor layer has a Zn content of 50 atomic % or more as a percentage of all metal elements contained therein, and the first oxide semiconductor layer is formed on the source-drain electrode and passivation layer side; the second oxide semiconductor layer contains at least one element selected from the group consisting of In, Ga, and Zn, and the second oxide semiconductor layer is formed on the substrate side; and the first oxide semiconductor layer is in direct contact both with the source-drain electrode and with the passivation layer.

Claims

1. A thin-film transistor structure, comprising, on a substrate, in order from the substrate side:

an oxide semiconductor layer;

a source-drain electrode; and

a passivation layer,

wherein;

the oxide semiconductor layer is a stacked product of a first oxide semiconductor layer and a second oxide semiconductor layer;

the first oxide semiconductor layer consists of, as a metal element, Zn;

or Zn and at least one element selected from the group consisting of Al, Ga, and Sn, wherein a content of Zn is 50 atomic % or more as a percentage of all metal elements contained therein,

the first oxide semiconductor layer is formed on the source-drain electrode and passivation layer side;

the second oxide semiconductor layer consists of, as a metal element, at least one selected from the group consisting of In, Ga, and Zn, and the second oxide semiconductor layer is formed on the substrate side;

and

the first oxide semiconductor layer is in direct contact both with the source-drain electrode and with the passivation layer.

2. The thin-film transistor structure according to claim 1, wherein the passivation layer is formed by a CVD (Chemical Vapor Deposition) method.

3. A thin-film transistor, comprising the thin-film transistor structure of claim 1.

4. A display device, comprising the thin-film transistor of claim 3.

5. The thin-film transistor structure according to claim 1, wherein the first oxide semiconductor layer has a Zn content of 60 atomic % or more as a percentage of all metal elements contained therein.

6. The thin-film transistor structure according to claim 1, wherein the first oxide semiconductor layer has a Zn content of 75 atomic % or more as a percentage of all metal elements contained therein.

7. The thin-film transistor structure according to claim 1, wherein the first oxide semiconductor layer has a film thickness of from 5 nm or more to 80 nm or less.

8. The thin-film transistor structure according to claim 1, wherein the second oxide semiconductor layer has a film thickness of from 30 nm or more to 200 nm or less.

9. A thin-film transistor structure, comprising, on a substrate, in order from the substrate side:

an oxide semiconductor layer;

an etch stop layer; and

a source-drain electrode,

wherein;

the oxide semiconductor layer is a stacked product of a first oxide semiconductor layer and a second oxide semiconductor layer;

the first oxide semiconductor layer consists of, as a metal element, Zn;

or Zn and at least one element selected from the group consisting of Al, Ga, and Sn, wherein a content of Zn is 50 atomic % or more as a percentage of all metal elements contained therein,

the first oxide semiconductor layer is formed on the etch stop layer and source-drain electrode side;

the second oxide semiconductor layer consists of, as a metal element, at least one selected from the group consisting of In, Ga, and Zn, and the second oxide semiconductor layer is formed on the substrate side;

and

the first oxide semiconductor layer is in direct contact both with the etch stop layer and with the source-drain electrode.

10. The thin-film transistor structure according to claim 9, wherein the etch stop layer is formed by a CVD (Chemical Vapor Deposition) method.

11. A thin-film transistor, comprising the thin-film transistor structure of claim 9.

12. A display device, comprising the thin-film transistor of claim 11.

13. The thin-film transistor structure according to claim 9, wherein the first oxide semiconductor layer has a Zn content of 60 atomic % or more as a percentage of all metal elements contained therein.

14. The thin-film transistor structure according to claim 9, wherein the first oxide semiconductor layer has a Zn content of 75 atomic % or more as a percentage of all metal elements contained therein.

15. The thin-film transistor structure according to claim 9, wherein the first oxide semiconductor layer has a film thickness of from 5 nm or more to 80 nm or less.

16. The thin-film transistor structure according to claim 9, wherein the second oxide semiconductor layer has a film thickness of from 30 nm or more to 200 nm or less.