Semiconductor device

• US 9,728,556 B2
• Filed: 10/18/2016
• Issued: 08/08/2017
• Est. Priority Date: 05/16/2013
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Miyake, Hiroyuki, Okazaki, Kenichi, Hayakawa, Masahiko, Matsuda, Shinpei
• Primary Examiner(s): Kim, Dennis Y
• Application Number:
  US15/296,395
• Publication Number:
  US 20170040348A1
• Time in Patent Office: 294 Days
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• 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 27/1237 with a different composition, shape, layout or thickness of the gate insulator in different devices
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 29/78648 arranged on opposing sides of the channel
• 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 29/78696 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 which includes an oxide semiconductor and in which formation of a parasitic channel due to a gate BT stress is suppressed is provided. Further, a semiconductor device including a transistor having excellent electrical characteristics is provided. The semiconductor device includes a transistor having a dual-gate structure in which an oxide semiconductor film is provided between a first gate electrode and a second gate electrode; gate insulating films are provided between the oxide semiconductor film and the first gate electrode and between the oxide semiconductor film and the second gate electrode; and in the channel width direction of the transistor, the first or second gate electrode faces a side surface of the oxide semiconductor film with the gate insulating film between the oxide semiconductor film and the first or second gate electrode.

Claims

1. A semiconductor device comprising:

a transistor comprising;

a first gate electrode;

a first gate insulating film over the first gate electrode;

a first oxide semiconductor film over a first region of the first gate insulating film;

a source electrode and a drain electrode over the first oxide semiconductor film;

a second gate insulating film over the first oxide semiconductor film, the source electrode, and the drain electrode; and

a second gate electrode over the second gate insulating film,

wherein the second gate electrode is in direct contact with a second region of the first gate insulating film,

wherein the first oxide semiconductor film is located between the first gate electrode and the second gate electrode,

wherein the first oxide semiconductor film comprises indium and zinc, and

wherein a thickness of the first region of the first gate insulating film is larger than a thickness of the second region of the first gate insulating film.

2. The semiconductor device according to claim 1, wherein a side surface of the first oxide semiconductor film faces the second gate electrode in a channel width direction of the transistor.

3. The semiconductor device according to claim 1, wherein the second gate insulating film is in contact with the first gate insulating film.

4. The semiconductor device according to claim 1, wherein the second gate electrode is electrically connected to the first gate electrode through a contact hole provided in the first gate insulating film.

5. The semiconductor device according to claim 1,

wherein the second gate electrode is electrically connected to the first gate electrode through a first contact hole and a second contact hole each provided in the first gate insulating film, and

wherein the first oxide semiconductor film is located between the first contact hole and the second contact hole.

6. The semiconductor device according to claim 1, wherein an outline of the first oxide semiconductor film is located inside an outline of the first gate electrode.

7. The semiconductor device according to claim 1, wherein the second gate insulating film comprises:

a first oxide insulating film;

a second oxide insulating film over the first oxide insulating film; and

a nitride insulating film over the second oxide insulating film.

8. The semiconductor device according to claim 1,

wherein the transistor comprises:

a second oxide semiconductor film over the first gate insulating film; and

a third oxide semiconductor film over the first oxide semiconductor film,

wherein the first oxide semiconductor film is located between the second oxide semiconductor film and the third oxide semiconductor film,

wherein the source electrode and the drain electrode are located over the third oxide semiconductor film, and

wherein each of the first oxide semiconductor film, the second oxide semiconductor film, and the third oxide semiconductor film comprises indium, gallium, and zinc.

9. The semiconductor device according to claim 1, wherein the transistor is provided over a substrate.

10. A display device comprising:

a pixel portion comprising;

a transistor comprising;

a first gate electrode;

a first gate insulating film over the first gate electrode;

a first oxide semiconductor film over a first region of the first gate insulating film;

a first electrode and a second electrode over the first oxide semiconductor film;

a second gate insulating film over the first oxide semiconductor film, the first electrode, and the second electrode;

a second gate electrode over the second gate insulating film; and

a third electrode in direct contact with the first gate insulating film and the first electrode,

wherein the second gate electrode is in direct contact with a second region of the first gate insulating film,

wherein the first oxide semiconductor film is located between the first gate electrode and the second gate electrode,

wherein the first oxide semiconductor film comprises indium and zinc, and

wherein a thickness of the first region of the first gate insulating film is larger than a thickness of the second region of the first gate insulating film.

11. The display device according to claim 10, wherein a side surface of the first oxide semiconductor film faces the second gate electrode in a channel width direction of the transistor.

12. The display device according to claim 10, wherein the second gate insulating film is in contact with the first gate insulating film.

13. The display device according to claim 10, wherein the second gate electrode is electrically connected to the first gate electrode through a contact hole provided in the first gate insulating film.

14. The display device according to claim 10,

wherein the second gate electrode is electrically connected to the first gate electrode through a first contact hole and a second contact hole each provided in the first gate insulating film, and

wherein the first oxide semiconductor film is located between the first contact hole and the second contact hole.

15. The display device according to claim 10, wherein an outline of the first oxide semiconductor film is located inside an outline of the first gate electrode.

16. The display device according to claim 10, wherein the second gate insulating film comprises:

a first oxide insulating film;

a second oxide insulating film over the first oxide insulating film; and

a nitride insulating film over the second oxide insulating film.

17. The display device according to claim 10,

wherein the transistor comprises:

a second oxide semiconductor film over the first gate insulating film; and

a third oxide semiconductor film over the first oxide semiconductor film,

wherein the first oxide semiconductor film is located between the second oxide semiconductor film and the third oxide semiconductor film,

wherein the first electrode and the second electrode are located over the third oxide semiconductor film, and

wherein each of the first oxide semiconductor film, the second oxide semiconductor film, and the third oxide semiconductor film comprises indium, gallium, and zinc.

18. The display device according to claim 10, wherein the transistor is provided over a substrate.

19. The display device according to claim 10, comprising a liquid crystal layer over the third electrode.