Thin film transistor

Patent metadata

Field	Value
Publication number	US-9343586-B2
Application number	US-201314399378-A
Country	US
Kind code	B2
Filing date	Jun 6, 2013
Priority date	Jun 6, 2012
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

Provided is a thin film transistor having an oxide semiconductor layer that has high mobility, excellent stress resistance, and good wet etching property. The thin film transistor comprises at least, a gate electrode, a gate insulating film, an oxide semiconductor layer, source-drain electrode and a passivation film, in this order on a substrate. The oxide semiconductor layer is a laminate comprising a first oxide semiconductor layer (IGZTO) and a second oxide semiconductor layer (IZTO). The second oxide semiconductor layer is formed on the gate insulating film, and the first oxide semiconductor layer is formed between the second oxide semiconductor layer and the passivation film. The contents of respective metal elements relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer are as follows; Ga: 5% or more; In: 25% or less (excluding 0%); Zn: 35 to 65%; and Sn: 8 to 30%.

First claim

The invention claimed is:

1. A thin film transistor, comprising;
a gate electrode, a gate insulating film, an oxide semiconductor layer, a source-drain electrode, and a passivation film configured to protect the source-drain electrode, on a substrate in this order,
wherein
the oxide semiconductor layer is a laminate comprising:
a first oxide semiconductor layer consisting of In, Ga, Zn, Sn, and O; and
a second oxide semiconductor layer consisting of In, Zn, Sn, and O,
wherein
the second oxide semiconductor layer is formed on the gate insulating film;
the first oxide semiconductor layer is formed between the second oxide semiconductor layer and the passivation film; and
the contents of respective metal elements relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer are:
In: smaller than or equal to 25 atomic %, excluding 0 atomic %;
Ga: larger than or equal to 5 atomic %;
Zn: larger than or equal to 35 atomic % and smaller than or equal to 65 atomic %; and
Sn: larger than or equal to 8 atomic % and smaller than or equal to 30 atomic %.

2. The thin film transistor according to claim 1 , wherein
the contents of respective metal elements relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer are:
In: smaller than or equal to 20 atomic %, excluding 0 atomic %;
Ga: larger than or equal to 15 atomic % and smaller than 50 atomic %;
Zn: larger than or equal to 35 atomic % and smaller than or equal to 65 atomic %; and
Sn: larger than or equal to 8 atomic % and smaller than or equal to 30 atomic %.

3. The thin film transistor according to claim 1 , wherein
an etching rate of the first oxide semiconductor layer to a wet etchant for the source-drain electrode is smaller than or equal to one half of an etching rate of the source-drain electrode.

4. The thin film transistor according to claim 1 , wherein
a thickness of the second oxide semiconductor layer is larger than or equal to 0.5 nm.

5. A display device, comprising the thin film transistor according to claim 1 .

6. The thin film transistor according to claim 2 , wherein an etching rate of the first oxide semiconductor layer to a wet etchant for the source-drain electrode is smaller than or equal to one half of an etching rate of the source-drain electrode.

7. The thin film transistor according to claim 2 , wherein a thickness of the second oxide semiconductor layer is larger than or equal to 0.5 nm.

8. A display device, comprising the thin film transistor according to claim 2 .

9. A thin film transistor, comprising;
a gate electrode, a gate insulating film, an oxide semiconductor layer, an etch stopper layer, a source-drain electrode, and a passivation film configured to protect the source-drain electrode, on a substrate in this order,
wherein
the oxide semiconductor layer is a laminate comprising:
a first oxide semiconductor layer consisting of In, Ga, Zn, Sn, and O; and
a second oxide semiconductor layer consisting of In, Zn, Sn, and O,
wherein
the contents of respective metal elements relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer are:
In: smaller than or equal to 25 atomic %, excluding 0 atomic %;
Ga: larger than 30 atomic % and smaller than 50 atomic %;
Zn: larger than or equal to 30.0 atomic % and smaller than or equal to 65 atomic %; and
Sn: larger than or equal to 5 atomic % and smaller than or equal to 30 atomic %.

10. The thin film transistor according to claim 9 , wherein
the contents of respective metal elements relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer are:
In: smaller than or equal to 20 atomic %, excluding 0 atomic %;
Ga: larger than 30 atomic % and smaller than 50 atomic %;
Zn: larger than or equal to 35 atomic % and smaller than or equal to 65 atomic %; and
Sn: larger than or equal to 8 atomic % and smaller than or equal to 30 atomic %.

11. The thin film transistor according to claim 9 , wherein
the second oxide semiconductor layer is formed on the gate insulating film; and
the first oxide semiconductor layer is formed between the second oxide semiconductor layer and the etch stopper layer.

12. The thin film transistor according to claim 9 , wherein
a thickness of the second oxide semiconductor layer is larger than or equal to 0.5 nm.

13. A display device, comprising the thin film transistor according to claim 9 .

14. The thin film transistor according to claim 9 , wherein the content of Ga relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer is equal to or larger than 33 atomic % and smaller than 50 atomic %.

15. The thin film transistor according to claim 9 , wherein the content of Ga relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer is equal to or larger than 38 atomic % and smaller than 50 atomic %.

16. The thin film transistor according to claim 9 , wherein the content of Ga relative to the total amount of all the metal elements other than oxygen in the first oxide semiconductor layer is larger than 40 atomic % and smaller than 50 atomic %.

17. The thin film transistor according to claim 10 , wherein
the second oxide semiconductor layer is formed on the gate insulating film; and
the first oxide semiconductor layer is formed between the second oxide semiconductor layer and the etch stopper layer.

18. The thin film transistor according to claim 10 , wherein a thickness of the second oxide semiconductor layer is larger than or equal to 0.5 nm.

19. A display device, comprising the thin film transistor according to claim 10 .

Assignees

• Kobe Steel Ltd

Inventors

• Goto Hiroshi
• Miki Aya
• Kishi Tomoya
• Hirose Kenta
• Morita Shinya
• Kugimiya Toshihiro

Classifications

• H10P14/3434

  being oxide semiconductor materials (Group IIB-VIA semiconductor materials H10P14/3424) · CPC title

• H10P14/3426

  Oxides · CPC title

• H10P14/22

  using physical deposition, e.g. vacuum deposition or sputtering · CPC title

• H10D30/6713

  characterised by the properties of the source or drain regions, e.g. compositions or sectional shapes · CPC title

• H10D30/6755 Primary

  Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate · CPC title