Semiconductor device

• US 8,723,176 B2
• Filed: 01/28/2013
• Issued: 05/13/2014
• Est. Priority Date: 02/02/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): LE, DUNG ANH
• Application Number:
  US13/751,721
• Publication Number:
  US 20130200365A1
• Time in Patent Office: 470 Days
• Field of Search: 257/40, 257/43, 257/57, 257/59, 257/72, 257/79, 257/347, 257/192, 257/E29.273
• US Class Current: 257/43
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/24 including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• 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

A semiconductor device in which release of oxygen from side surfaces of an oxide semiconductor film including c-axis aligned crystal parts can be prevented is provided. The semiconductor device includes a first oxide semiconductor film, a second oxide semiconductor film including c-axis aligned crystal parts, and an oxide film including c-axis aligned crystal parts. In the semiconductor device, the first oxide semiconductor film, the second oxide semiconductor film, and the oxide film are each formed using a IGZO film, where the second oxide semiconductor film has a higher indium content than the first oxide semiconductor film, the first oxide semiconductor film has a higher indium content than the oxide film, the oxide film has a higher gallium content than the first oxide semiconductor film, and the first oxide semiconductor film has a higher gallium content than the second oxide semiconductor film.

Claims

1. A semiconductor device comprising:

an island-like semiconductor film comprising;

a first oxide semiconductor film; and

a second oxide semiconductor film including a c-axis aligned crystal part;

an oxide film adjacent to the second oxide semiconductor film interposed between the first oxide semiconductor film and the oxide film, wherein the oxide film comprises a c-axis aligned crystal part;

a gate electrode adjacent to the oxide film interposed between the island-like semiconductor film and the gate electrode; and

a source electrode and a drain electrode electrically connected to the island-like semiconductor film,

wherein the first oxide semiconductor film, the second oxide semiconductor film, and the oxide film each include an oxide containing indium, gallium, and zinc,

wherein an indium content in the second oxide semiconductor film is higher than an indium content in the first oxide semiconductor film,

wherein the indium content in the first oxide semiconductor film is higher than an indium content in the oxide film,

wherein a gallium content in the oxide film is higher than a gallium content in the first oxide semiconductor film, and

wherein the gallium content in the first oxide semiconductor film is higher than a gallium content in the second oxide semiconductor film.

2. The semiconductor device according to claim 1, wherein the oxide film has an insulating property.

3. The semiconductor device according to claim 1,

wherein the gate electrode is over the island-like semiconductor film, and

wherein the source electrode and the drain electrode are over the island-like semiconductor film.

4. The semiconductor device according to claim 1,

wherein the oxide film covers at least side surfaces of the island-like semiconductor film in a channel length direction.

5. The semiconductor device according to claim 1, further comprising an oxidation film,

wherein the island-like semiconductor film is over the oxidation film.

6. The semiconductor device according to claim 1,

wherein an oxygen-transmitting property of the oxide film in a perpendicular direction to a surface of the island-like semiconductor film is lower than an oxygen-transmitting property of the oxide film in a horizontal direction to the surface of the island-like semiconductor film.

7. The semiconductor device according to claim 1, wherein an atomic ratio of In, Ga, and Zn in the first oxide semiconductor film is substantially 1:

1;

1.

8. The semiconductor device according to claim 1, wherein an atomic ratio of In, Ga, and Zn in the second oxide semiconductor film is substantially 3:

1;

2.

9. The semiconductor device according to claim 1, wherein an atomic ratio of In, Ga, and Zn in the oxide film is substantially 1:

3;

2.

10. The semiconductor device according to claim 1, wherein the oxide film has a structure in which an insulating film is stacked over a film including an oxide containing In, Ga, and Zn.

11. The semiconductor device according to claim 1, wherein an insulating film is provided over the gate electrode, the source electrode, and the drain electrode.

12. The semiconductor device according to claim 1,

wherein in the c-axis aligned crystal part of the second oxide semiconductor film, a plurality of metal atoms and oxygen atoms are arranged in a layered manner along a c-axis direction parallel to a normal vector of a surface where the second oxide semiconductor film is formed, and

wherein in the c-axis aligned crystal part of the oxide film, a plurality of metal atoms and oxygen atoms are arranged in a layered manner along a c-axis direction parallel to a normal vector of a surface where the oxide film is formed.

13. A semiconductor device comprising:

an island-like semiconductor film comprising;

a first oxide semiconductor film; and

a second oxide semiconductor film including a c-axis aligned crystal part over the first oxide semiconductor film;

an oxide film over the island-like semiconductor film, the oxide film comprising a c-axis aligned crystal part;

a gate electrode over the oxide film; and

a source electrode and a drain electrode over and electrically connected to the island-like semiconductor film,

wherein the first oxide semiconductor film, the second oxide semiconductor film, and the oxide film each include an oxide containing indium, gallium, and zinc,

wherein an indium content in the second oxide semiconductor film is higher than an indium content in the first oxide semiconductor film,

wherein the indium content in the first oxide semiconductor film is higher than an indium content in the oxide film,

wherein a gallium content in the oxide film is higher than a gallium content in the first oxide semiconductor film, and

wherein the gallium content in the first oxide semiconductor film is higher than a gallium content in the second oxide semiconductor film.

14. The semiconductor device according to claim 13,

wherein the oxide film covers at least side surfaces of the island-like semiconductor film in a channel length direction.

15. The semiconductor device according to claim 13, wherein the oxide film has an insulating property.

16. The semiconductor device according to claim 13, further comprising a sidewall in contact with side surfaces of the gate electrode.

17. A semiconductor device comprising:

an island-like semiconductor film comprising;

a first oxide semiconductor film; and

a second oxide semiconductor film including a c-axis aligned crystal part over the first oxide semiconductor film;

an oxide film over the island-like semiconductor film, the oxide film comprising a c-axis aligned crystal part;

a gate electrode over the oxide film;

a first source electrode and a first drain electrode in contact with at least side surfaces of the island-like semiconductor film; and

a second source electrode and a second drain electrode over the island-like semiconductor film, wherein the second source electrode and the second drain electrode are electrically connected to the first source electrode and the first drain electrode, respectively,

wherein the first oxide semiconductor film, the second oxide semiconductor film, and the oxide film each include an oxide containing indium, gallium, and zinc,

wherein an indium content in the second oxide semiconductor film is higher than an indium content in the first oxide semiconductor film,

wherein the indium content in the first oxide semiconductor film is higher than an indium content in the oxide film,

wherein a gallium content in the oxide film is higher than a gallium content in the first oxide semiconductor film, and

wherein the gallium content in the first oxide semiconductor film is higher than a gallium content in the second oxide semiconductor film.

18. The semiconductor device according to claim 17, wherein the oxide film has an insulating property.

19. The semiconductor device according to claim 17,

wherein the oxide film covers at least side surfaces of the island-like semiconductor film in a channel length direction.

20. The semiconductor device according to claim 17, further comprising a sidewall in contact with side surfaces of the gate electrode.