Semiconductor device and display device including the semiconductor device

• US 10,032,929 B2
• Filed: 08/23/2017
• Issued: 07/24/2018
• Est. Priority Date: 05/22/2015
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koezuka, Junichi, Jintyou, Masami, Shima, Yukinori
• Primary Examiner(s): WOLDEGEORGIS, ERMIAS T
• Application Number:
  US15/683,845
• Publication Number:
  US 20170373196A1
• Time in Patent Office: 335 Days
• Field of Search: None
• 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 29/045 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 29/66742 Thin film unipolar transistors
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• 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 29/78648 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 29/78693 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

The reliability of a transistor including an oxide semiconductor is improved. The transistor in a semiconductor device includes a first oxide semiconductor film over a first insulating film, a gate insulating film over the first oxide semiconductor film, a second oxide semiconductor film over the gate insulating film, and a second insulating film over the first oxide semiconductor film and the second oxide semiconductor film. The first oxide semiconductor film includes a channel region overlapping with the second oxide semiconductor film, a source region and a drain region each in contact with the second insulating film. The channel region includes a first layer and a second layer in contact with a top surface of the first layer and covering a side surface of the first layer in the channel width direction. The second oxide semiconductor film has a higher carrier density than the first oxide semiconductor film.

Claims

1. A semiconductor device comprising a transistor,

wherein the transistor comprises:

a first oxide semiconductor film over a first insulating film;

a gate insulating film over the first oxide semiconductor film;

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

a second insulating film over the first oxide semiconductor film and the second oxide semiconductor film,

wherein the first oxide semiconductor film comprises;

a channel region overlapping with the second oxide semiconductor film;

a source region in contact with the second insulating film; and

a drain region in contact with the second insulating film,

wherein the channel region comprises;

a first layer; and

a second layer which is in contact with a top surface of the first layer and covers a side surface of the first layer in a channel width direction, and

wherein the second oxide semiconductor film has a higher carrier density than the first oxide semiconductor film, and

wherein the second oxide semiconductor film comprises a plurality of crystals.

2. The semiconductor device according to claim 1, further comprising a region in which an upper end portion of the gate insulating film is aligned with or positioned further outward than a lower end portion of the second oxide semiconductor film.

3. The semiconductor device according to claim 1, wherein the second insulating film comprises at least one of nitrogen and hydrogen.

4. The semiconductor device according to claim 1, wherein the transistor further comprises:

a third insulating film over the second insulating film;

a source electrode connected to the source region through an opening in the second insulating film and the third insulating film; and

a drain electrode connected to the drain region through an opening in the second insulating film and the third insulating film.

5. The semiconductor device according to claim 1, wherein the source region and the drain region each comprise a region having the same hydrogen concentration as the second oxide semiconductor film.

6. The semiconductor device according to claim 1, wherein the source region and the drain region each comprise at least one of hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, and a rare gas.

7. The semiconductor device according to claim 1, wherein at least one of the first oxide semiconductor film and the second oxide semiconductor film comprises oxygen, In, Zn, and M (M is Al, Ga, Y, or Sn).

8. The semiconductor device according to claim 1,

wherein each of c-axes of the plurality of the crystals in the second oxide semiconductor film is substantially perpendicular to an upper surface of the second oxide semiconductor film.

9. A semiconductor device comprising a transistor,

wherein the transistor comprises:

a first oxide semiconductor film over a first insulating film;

a gate insulating film over the first oxide semiconductor film;

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

a second insulating film over the first oxide semiconductor film and the second oxide semiconductor film,

wherein the first oxide semiconductor film comprises;

a channel region overlapping with the second oxide semiconductor film;

a source region in contact with the second insulating film; and

a drain region in contact with the second insulating film,

wherein the channel region comprises;

a first layer;

a second layer which is in contact with a top surface of the first layer and covers a side surface of the first layer in a channel width direction; and

a third layer in contact with a bottom surface of the first layer, and

wherein the second oxide semiconductor film has a higher carrier density than the first oxide semiconductor film, and

wherein the second oxide semiconductor film comprises a plurality of crystals.

10. The semiconductor device according to claim 9, further comprising a region in which an upper end portion of the gate insulating film is aligned with or positioned further outward than a lower end portion of the second oxide semiconductor film.

11. The semiconductor device according to claim 9, wherein the second insulating film comprises at least one of nitrogen and hydrogen.

12. The semiconductor device according to claim 9, wherein the transistor further comprises:

a third insulating film over the second insulating film;

a source electrode connected to the source region through an opening in the second insulating film and the third insulating film; and

a drain electrode connected to the drain region through an opening in the second insulating film and the third insulating film.

13. The semiconductor device according to claim 9, wherein the source region and the drain region each comprise a region having the same hydrogen concentration as the second oxide semiconductor film.

14. The semiconductor device according to claim 9, wherein the source region and the drain region each comprise at least one of hydrogen, boron, carbon, nitrogen, fluorine, phosphorus, sulfur, and a rare gas.

15. The semiconductor device according to claim 9, wherein at least one of the first oxide semiconductor film and the second oxide semiconductor film comprises oxygen, In, Zn, and M (M is Al, Ga, Y, or Sn).

16. The semiconductor device according to claim 9,

wherein each of c-axes of the plurality of the crystals in the second oxide semiconductor film is substantially perpendicular to an upper surface of the second oxide semiconductor film.