Semiconductor device

• US 9,324,875 B2
• Filed: 10/15/2013
• Issued: 04/26/2016
• Est. Priority Date: 10/17/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Ingham, John C
• Application Number:
  US14/054,180
• Publication Number:
  US 20140103346A1
• Time in Patent Office: 924 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 29/41733 for thin film transistors with insulated gate
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• 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 29/7869 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 includes a transistor which includes a gate electrode, a gate insulating film in contact with the gate electrode, and a stacked-layer oxide film facing the gate electrode with the gate insulating film provided therebetween. In the semiconductor device, the stacked-layer oxide film includes at least a plurality of oxide films, at least one of the plurality of oxide films includes a channel formation region, a channel length of the transistor is greater than or equal to 5 nm and less than 60 nm, and a thickness of the gate insulating film is larger than a thickness of the oxide film including the channel formation region.

Claims

1. A semiconductor device comprising a transistor, the transistor comprising:

a gate electrode;

a stacked-layer oxide film comprising a first oxide semiconductor film, a second oxide semiconductor film, and a third oxide semiconductor film;

a gate insulating film between the gate electrode and the stacked-layer oxide film; and

a source electrode and a drain electrode which are in contact with the stacked-layer oxide film,

wherein at least one of the first-third oxide semiconductor films includes a channel formation region,

wherein a channel length of the transistor is greater than or equal to 5 nm and less than 60 nm,

wherein a thickness of the gate insulating film is larger than a thickness of the one of the first-third oxide semiconductor films including the channel formation region,

wherein each of the source electrode and the drain electrode comprises a first conductive layer and a second conductive layer over the first conductive layer,

wherein the third oxide semiconductor film is between the source electrode of the first conductive layer and the second conductive layer over the first conductive layer, and is between the drain electrode of the first conductive layer and the second conductive layer,

wherein a side surface of the second conductive layer extends beyond a side surface of the first conductive layer in a channel length direction, and

wherein the side surface of the second conductive layer is over the channel formation region.

2. The semiconductor device according to claim 1, wherein the channel length of the transistor is greater than or equal to 10 nm and less than or equal to 40 nm.

3. The semiconductor device according to claim 1, wherein a thickness of the gate insulating film which is obtained by conversion into a thickness of a silicon oxide film is greater than or equal to 20 nm and less than or equal to 30 nm.

4. The semiconductor device according to claim 1, wherein an off-state leakage current of the transistor at 85°

C. is less than 1 zA/μ

m.

5. The semiconductor device according to claim 1, wherein an off-state leakage current of the transistor at 85°

C. is less than 1 yA/μ

m.

6. The semiconductor device according to claim 1,

wherein the second oxide semiconductor film is over the first oxide semiconductor film, and the third oxide semiconductor film is over the first oxide semiconductor film with the second oxide semiconductor film provided therebetween, and

wherein the second oxide semiconductor film includes the channel formation region.

7. The semiconductor device according to claim 1,

wherein the second oxide semiconductor film is over the first oxide semiconductor film, and the third oxide semiconductor film is over the first oxide semiconductor film with the second oxide semiconductor film provided therebetween,

wherein the second oxide semiconductor film is a c-axis aligned crystalline oxide semiconductor film including crystal parts, and

wherein the third oxide semiconductor film is a c-axis aligned crystalline oxide semiconductor film or an amorphous oxide film.

8. The semiconductor device according to claim 1, further comprising:

an oxide film over the first conductive layer and the second conductive layer, the oxide film being in contact with the stacked-layer oxide film; and

a third conductive layer overlapping with the first conductive layer with the oxide film provided therebetween and a fourth conductive layer overlapping with the second conductive layer with the oxide film provided therebetween.

9. A semiconductor device comprising a transistor, the transistor comprising:

a gate electrode over an insulating surface;

a stacked-layer oxide film including oxide films;

a gate insulating film between the gate electrode and the stacked-layer oxide film; and

a source electrode and a drain electrode which are in contact with the stacked-layer oxide film,

wherein at least one of the oxide films includes a channel formation region,

wherein a channel length of the transistor is greater than or equal to 5 nm and less than 60 nm,

wherein a thickness of the gate insulating film is larger than a thickness of the one of the oxide films including the channel formation region,

wherein each of the source electrode and the drain electrode comprises a first conductive layer and a second conductive layer over the first conductive layer, and

wherein a bottom surface of the second conductive layer is in contact with a top surface of the stacked-layer oxide film and the insulating surface.

10. The semiconductor device according to claim 9,

wherein the stacked-layer oxide film includes a region where the gate electrode overlaps with the source electrode or the drain electrode in a channel length direction, and

wherein a length of the region is greater than or equal to 5% and less than 10% of the channel length.

11. The semiconductor device according to claim 9, wherein a material of the first conductive layer is the same as a material of the second conductive layer.

12. The semiconductor device according to claim 9, wherein a material of the first conductive layer is different from a material of the second conductive layer.

13. The semiconductor device according to claim 9, wherein the channel length of the transistor is greater than or equal to 10 nm and less than or equal to 40 nm.

14. The semiconductor device according to claim 9, wherein a thickness of the gate insulating film which is obtained by conversion into a thickness of a silicon oxide film is greater than or equal to 20 nm and less than or equal to 30 nm.

15. The semiconductor device according to claim 9, wherein an off-state leakage current of the transistor at 85°

C. is less than 1 zA/μ

m.

16. The semiconductor device according to claim 9, wherein an off-state leakage current of the transistor at 85°

C. is less than 1 yA/μ

m.

17. The semiconductor device according to claim 9, wherein the stacked-layer oxide film is a stacked film of oxide semiconductor films.

18. The semiconductor device according to claim 9,

wherein the oxide films include a first oxide film, a second oxide film over the first oxide film, and a third oxide film over the first oxide film with the second oxide film provided therebetween, and

wherein the second oxide film includes the channel formation region.

19. The semiconductor device according to claim 9,

wherein the oxide films include a first oxide film, a second oxide film over the first oxide film, and a third oxide film over the first oxide film with the second oxide film provided therebetween,

wherein the second oxide film is a c-axis aligned crystalline oxide semiconductor film including crystal parts, and

wherein the third oxide film is a c-axis aligned crystalline oxide semiconductor film or an amorphous oxide film.