Semiconductor device and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-11715801-B2
Application number	US-202217687817-A
Country	US
Kind code	B2
Filing date	Mar 7, 2022
Priority date	Mar 6, 2009
Publication date	Aug 1, 2023
Grant date	Aug 1, 2023

Abstract

It is an object to provide a highly reliable semiconductor device including a thin film transistor with stable electric characteristics. In a semiconductor device including an inverted staggered thin film transistor whose semiconductor layer is an oxide semiconductor layer, a buffer layer is provided over the oxide semiconductor layer. The buffer layer is in contact with a channel formation region of the semiconductor layer and source and drain electrode layers. A film of the buffer layer has resistance distribution. A region provided over the channel formation region of the semiconductor layer has lower electrical conductivity than the channel formation region of the semiconductor layer, and a region in contact with the source and drain electrode layers has higher electrical conductivity than the channel formation region of the semiconductor layer.

First claim

What is claimed is:

1. A semiconductor device comprising:
a first oxide semiconductor film comprising a channel formation region;
a second oxide semiconductor film comprising In, Al, and Zn; and
an electrode electrically connected to the first oxide semiconductor film through the second oxide semiconductor film,
wherein the second oxide semiconductor film comprises a first region in contact with the electrode and not overlapping with the first oxide semiconductor film,
wherein the second oxide semiconductor film comprises a second region in contact with the first oxide semiconductor film, and
wherein a resistance of the first region is lower than a resistance of the second region.

2. The semiconductor device according to claim 1 , wherein the second oxide semiconductor film comprises a third region covering an end portion of the first oxide semiconductor film.

3. The semiconductor device according to claim 1 , wherein the first oxide semiconductor film comprises In, Ga, and Zn.

4. The semiconductor device according to claim 1 , wherein the electrode comprises a metal whose normal electrode potential is smaller than normal electrode potential of zinc.

5. A semiconductor device comprising:
a gate electrode;
an insulating layer over the gate electrode;
a first oxide semiconductor film over the insulating layer, the first oxide semiconductor film comprising a channel formation region;
a second oxide semiconductor film over the first oxide semiconductor film, the second oxide semiconductor film comprising In, Al, and Zn; and
an electrode over the second oxide semiconductor film,
wherein the second oxide semiconductor film comprises a first region in contact with the electrode and not overlapping with the first oxide semiconductor film,
wherein the second oxide semiconductor film comprises a second region in contact with the first oxide semiconductor film, and
wherein a resistance of the first region is lower than a resistance of the second region.

6. The semiconductor device according to claim 5 , wherein the second oxide semiconductor film comprises a third region covering an end portion of the first oxide semiconductor film.

7. The semiconductor device according to claim 5 , wherein the first oxide semiconductor film comprises In, Ga, and Zn.

8. The semiconductor device according to claim 5 , wherein the electrode comprises a metal whose normal electrode potential is smaller than normal electrode potential of zinc.

9. A semiconductor device comprising:
a gate electrode;
an insulating layer over the gate electrode;
a first oxide semiconductor film over the insulating layer, the first oxide semiconductor film comprising a channel formation region;
a second oxide semiconductor film over and in direct contact with the first oxide semiconductor film, the second oxide semiconductor film comprising In, Al, and Zn; and
an electrode over the second oxide semiconductor film,
wherein the second oxide semiconductor film comprises a first region in direct contact with the electrode and not overlapping with the first oxide semiconductor film,
wherein the second oxide semiconductor film comprises a second region in contact with the first oxide semiconductor film, and
wherein a resistance of the first region is lower than a resistance of the second region.

10. The semiconductor device according to claim 9 , wherein the second oxide semiconductor film comprises a third region covering an end portion of the first oxide semiconductor film.

11. The semiconductor device according to claim 9 , wherein the first oxide semiconductor film comprises In, Ga, and Zn.

12. The semiconductor device according to claim 9 , wherein the electrode comprises a metal whose normal electrode potential is smaller than normal electrode potential of zinc.

Assignees

• Semiconductor Energy Lab

Inventors

• Sakata Junichiro
• Hirohashi Takuya
• Kishida Hideyuki

Classifications

• H10P14/3426

  Oxides · CPC title

• H10P14/3434

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

• H10P14/22

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

• H10D30/6739

  Conductor-insulator-semiconductor electrodes · CPC title

• H10D30/6713

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