Semiconductor device

• US 10,608,116 B2
• Filed: 12/18/2017
• Issued: 03/31/2020
• Est. Priority Date: 04/02/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Pham, Thanhha S
• Application Number:
  US15/844,676
• Publication Number:
  US 20180122951A1
• Time in Patent Office: 834 Days
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• 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
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous

Abstract

An object is to stabilize electric characteristics of a semiconductor device including an oxide semiconductor to increase reliability. The semiconductor device includes an insulating film; a first metal oxide film on and in contact with the insulating film; an oxide semiconductor film partly in contact with the first metal oxide film; source and drain electrodes electrically connected to the oxide semiconductor film; a second metal oxide film partly in contact with the oxide semiconductor film; a gate insulating film on and in contact with the second metal oxide film; and a gate electrode over the gate insulating film.

Claims

1. A semiconductor device comprising:

a first metal oxide film over a substrate, the first metal oxide film comprising gallium;

an oxide semiconductor film in contact with the first metal oxide film;

source and drain electrodes in contact with the oxide semiconductor film;

a second metal oxide film in contact with the oxide semiconductor film, the second metal oxide film comprising gallium; and

a gate electrode over the second metal oxide film,

wherein an energy at a bottom of a conduction band of each of the first metal oxide film and the second metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film, and

wherein the second metal oxide film is in contact with a top surface of each of the source and drain electrodes.

2. The semiconductor device according to claim 1, wherein each of the first metal oxide film and the second metal oxide film comprises a constituent element of the oxide semiconductor film.

3. The semiconductor device according to claim 1, wherein a proportion of a constituent element of the first metal oxide film is equal to a proportion of a constituent element of the second metal oxide film.

4. The semiconductor device according to claim 1, wherein an energy gap of each of the first metal oxide film and the second metal oxide film is larger than an energy gap of the oxide semiconductor film.

5. The semiconductor device according to claim 1, wherein a side surface of the oxide semiconductor film is in contact with the second metal oxide film in a channel width direction.

6. The semiconductor device according to claim 1, wherein the first metal oxide film is in contact with the second metal oxide film in a channel width direction.

7. A semiconductor device comprising:

a first metal oxide film over a substrate, the first metal oxide film comprising gallium;

an oxide semiconductor film in contact with the first metal oxide film;

source and drain electrodes in contact with the oxide semiconductor film;

a second metal oxide film in contact with the oxide semiconductor film, the second metal oxide film comprising gallium;

a gate insulating film over the second metal oxide film; and

a gate electrode over the gate insulating film,

wherein an energy at a bottom of a conduction band of each of the first metal oxide film and the second metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film, and

wherein the second metal oxide film is in contact with a top surface of each of the source and drain electrodes.

8. The semiconductor device according to claim 7, wherein each of the first metal oxide film and the second metal oxide film comprises a constituent element of the oxide semiconductor film.

9. The semiconductor device according to claim 7, wherein a proportion of a constituent element of the first metal oxide film is equal to a proportion of a constituent element of the second metal oxide film.

10. The semiconductor device according to claim 7, wherein an energy gap of each of the first metal oxide film and the second metal oxide film is larger than an energy gap of the oxide semiconductor film.

11. The semiconductor device according to claim 7, wherein a side surface of the oxide semiconductor film is in contact with the second metal oxide film in a channel width direction.

12. The semiconductor device according to claim 7, wherein the first metal oxide film is in contact with the second metal oxide film in a channel width direction.