Semiconductor device and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-10014414-B2
Application number	US-201414190874-A
Country	US
Kind code	B2
Filing date	Feb 26, 2014
Priority date	Feb 28, 2013
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A transistor or the like having high field-effect mobility is provided. A transistor or the like having stable electrical characteristics is provided. A semiconductor device including a first oxide semiconductor layer, a second oxide semiconductor layer, a gate insulating film, and a gate electrode which partly overlap with one another is provided. The second oxide semiconductor layer is positioned between the first oxide semiconductor layer and the gate insulating film. The gate insulating film is positioned between the second oxide semiconductor layer and the gate electrode. The first oxide semiconductor layer has fewer oxygen vacancies than those of the second oxide semiconductor layer.

First claim

What is claimed is:

1. A method for manufacturing a semiconductor device, the method comprising the steps of:
forming a first oxide semiconductor layer; and
forming a second oxide semiconductor layer so that the number of oxygen vacancies in the second oxide semiconductor layer is larger than the number of oxygen vacancies in the first oxide semiconductor layer,
wherein the second oxide semiconductor layer is formed over and in contact with the first oxide semiconductor layer,
wherein the first oxide semiconductor layer is formed by a sputtering method under a first atmosphere containing oxygen, and
wherein the second oxide semiconductor layer is formed by a sputtering method under a second atmosphere having a lower concentration in oxygen than the first atmosphere.

2. The method for manufacturing a semiconductor device, according to claim 1 , wherein the first oxide semiconductor layer and the second oxide semiconductor layer are formed using the same target.

3. The method for manufacturing a semiconductor device, according to claim 2 , wherein an atomic ratio of an element in the first oxide semiconductor layer is different from an atomic ratio of the element in the second oxide semiconductor layer.

4. The method for manufacturing a semiconductor device, according to claim 1 , further comprising the steps of:
forming a gate insulating film in contact with the second oxide semiconductor layer; and
forming a gate electrode in contact with the gate insulating film.

5. The method for manufacturing a semiconductor device, according to claim 1 , wherein a proportion of oxygen in the second atmosphere is smaller than 10 volume %.

6. The method for manufacturing a semiconductor device, according to claim 1 , wherein the first oxide semiconductor layer and the second oxide semiconductor layer are formed in the same deposition chamber.

7. A method for manufacturing a semiconductor device, the method comprising the steps of:
forming a first oxide semiconductor layer;
forming a second oxide semiconductor layer so that the number of oxygen vacancies in the second oxide semiconductor layer is larger than the number of oxygen vacancies in the first oxide semiconductor layer; and
forming a third oxide semiconductor layer so that the number of oxygen vacancies in the third oxide semiconductor layer is smaller than the number of oxygen vacancies in the second oxide semiconductor layer,
wherein the second oxide semiconductor layer is formed over and in contact with the first oxide semiconductor layer,
wherein the third oxide semiconductor layer is formed over and in contact with the second oxide semiconductor layer,
wherein the first oxide semiconductor layer is formed by a sputtering method under a first atmosphere containing oxygen,
wherein the third oxide semiconductor layer is formed by a sputtering method under a second atmosphere containing oxygen, and
wherein the second oxide semiconductor layer is formed by a sputtering method under a third atmosphere having a lower concentration in oxygen than the first atmosphere and the second atmosphere.

8. The method for manufacturing a semiconductor device, according to claim 7 , wherein the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer are formed using the same target.

9. The method for manufacturing a semiconductor device, according to claim 8 , wherein an atomic ratio of an element in the first oxide semiconductor layer is different from an atomic ratio of the element in the second oxide semiconductor layer.

10. The method for manufacturing a semiconductor device, according to claim 7 , further comprising the steps of:
forming a gate insulating film in contact with the third oxide semiconductor layer; and
forming a gate electrode in contact with the gate insulating film.

11. The method for manufacturing a semiconductor device, according to claim 7 , wherein a proportion of oxygen in the third atmosphere is smaller than 10 volume %.

12. The method for manufacturing a semiconductor device, according to claim 7 , wherein the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer are formed in the same deposition chamber.

Assignees

• Semiconductor Energy Lab

Inventors

• Tokunaga Hajime
• Handa Takuya
• Okazaki Kenichi

Classifications

• H10D30/0312

  characterised by the gate electrodes · CPC title

• H01L29/66742

  Electricity · mapped topic

• H01L29/7869 Primary

  Electricity · mapped topic

• H01L29/66969

  Electricity · mapped topic

• H10D30/6757

  characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715) · CPC title