Semiconductor device

• US 8,946,704 B2
• Filed: 04/29/2014
• Issued: 02/03/2015
• 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:
  US14/264,311
• Publication Number:
  US 20140231803A1
• Time in Patent Office: 280 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:

a first oxide semiconductor film;

a second oxide semiconductor film over the first oxide semiconductor film, the second oxide semiconductor film comprising a channel region and a low-resistance region;

a gate insulating film over the second oxide semiconductor film;

a gate electrode over the gate insulating film;

a first insulating film in contact with a side surface of the gate electrode;

a first electrode in contact with a side surface of the second oxide semiconductor film; and

a second electrode in contact with the first electrode, the second oxide semiconductor film, and the first insulating film,

wherein a resistance of the low-resistance region is lower than a resistance of the channel region,

wherein the gate electrode overlaps the channel region, and

wherein the low-resistance region is in contact with the first electrode and the second electrode.

2. The semiconductor device according to claim 1, wherein the second electrode is in contact with a top surface of the second oxide semiconductor film.

3. The semiconductor device according to claim 1, wherein the gate electrode faces a side surface of the channel region.

4. The semiconductor device according to claim 1, wherein the second oxide semiconductor film comprises a c-axis aligned crystal part.

5. The semiconductor device according to claim 1,

wherein each of the first oxide semiconductor film and the second oxide semiconductor film comprises 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, and

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

6. The semiconductor device according to claim 1, wherein an atomic ratio of indium, gallium, and zinc in the first oxide semiconductor film is substantially 1:

1;

1.

7. The semiconductor device according to claim 1, wherein an atomic ratio of indium, gallium, and zinc in the second oxide semiconductor film is substantially 3:

1;

2.

8. The semiconductor device according to claim 4,

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.

9. A semiconductor device comprising:

a first oxide semiconductor film;

a second oxide semiconductor film over the first oxide semiconductor film, the second oxide semiconductor film comprising a channel region and a low-resistance region;

a gate insulating film over the second oxide semiconductor film;

a gate electrode over the gate insulating film;

a first insulating film in contact with a side surface of the gate electrode;

a first electrode in contact with a side surface of the second oxide semiconductor film; and

a second electrode in contact with the first electrode, the second oxide semiconductor film, and the first insulating film,

wherein a resistance of the low-resistance region is lower than a resistance of the channel region,

wherein the gate electrode overlaps the channel region,

wherein the low-resistance region is in contact with the first electrode and the second electrode, and

wherein the side surface of the gate electrode and a boundary between the channel region and the low-resistance region are aligned.

10. The semiconductor device according to claim 9, wherein the second electrode is in contact with a top surface of the second oxide semiconductor film.

11. The semiconductor device according to claim 9, wherein the gate electrode faces a side surface of the channel region.

12. The semiconductor device according to claim 9, wherein the second oxide semiconductor film comprises a c-axis aligned crystal part.

13. The semiconductor device according to claim 9,

wherein each of the first oxide semiconductor film and the second oxide semiconductor film comprises 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, and

wherein a 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 9, wherein an atomic ratio of indium, gallium, and zinc in the first oxide semiconductor film is substantially 1:

1;

1.

15. The semiconductor device according to claim 9, wherein an atomic ratio of indium, gallium, and zinc in the second oxide semiconductor film is substantially 3:

1;

2.

16. The semiconductor device according to claim 12,

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.