Semiconductor device and electronic device including the semiconductor device

Patent metadata

Field	Value
Publication number	US-9685563-B2
Application number	US-201615159873-A
Country	US
Kind code	B2
Filing date	May 20, 2016
Priority date	Jun 13, 2014
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

A semiconductor device includes a first oxide semiconductor film, a second oxide semiconductor film over the first oxide semiconductor film, a source electrode in contact with the second oxide semiconductor film, a drain electrode in contact with the second oxide semiconductor film, a metal oxide film over the second oxide semiconductor film, the source electrode, and the drain electrode, a gate insulating film over the metal oxide film, and a gate electrode over the gate insulating film. The metal oxide film contains M (M represents Ti, Ga, Y, Zr, La, Ce, Nd, or Hf) and Zn. The metal oxide film includes a portion where x/(x+y) is greater than 0.67 and less than or equal to 0.99 when a target has an atomic ratio of M:Zn=x:y.

First claim

The invention claimed is:

1. A semiconductor device comprising:
a first oxide semiconductor film;
a second oxide semiconductor film over the first oxide semiconductor film;
a source electrode over the second oxide semiconductor film;
a drain electrode over the second oxide semiconductor film;
a metal oxide film over the second oxide semiconductor film, the source electrode, and the drain electrode; and
a gate electrode overlapping with the second oxide semiconductor film with a gate insulating film interposed therebetween,
wherein the metal oxide film comprises an element M (M represents Ti, Ga, Y, Zr, La, Ce, Nd, or Hf) and Zn, and
wherein the metal oxide film comprises a portion where x/(x+y) is greater than 0.67 and less than or equal to 0.99 when an atomic ratio of the element M to Zn in a target is represented by M:Zn=x:y.

2. The semiconductor device according to claim 1 ,
wherein the element M is Ga.

3. The semiconductor device according to claim 1 ,
wherein the second oxide semiconductor film comprises a plurality of crystal parts having c-axis alignment, and c-axes of the plurality of crystal parts are aligned in a direction parallel to a normal vector to an upper surface of the second oxide semiconductor film.

4. The semiconductor device according to claim 1 ,
wherein the gate insulating film is in contact with the gate electrode.

5. The semiconductor device according to claim 1 ,
wherein an electron affinity of the second oxide semiconductor film is higher than an electron affinity of the first oxide semiconductor film.

6. An electronic device comprising the semiconductor device according to claim 1 .

7. A semiconductor device comprising:
a first oxide semiconductor film;
a second oxide semiconductor film over the first oxide semiconductor film;
a source electrode over the second oxide semiconductor film;
a drain electrode over the second oxide semiconductor film;
a metal oxide film over the second oxide semiconductor film, the source electrode, and the drain electrode; and
a gate electrode overlapping with the second oxide semiconductor film with a gate insulating film interposed therebetween,
wherein the first oxide semiconductor film comprises a first side surface and a second side surface,
wherein the first side surface is aligned with a side surface of the source electrode,
wherein the second side surface is aligned with a side surface of the drain electrode,
wherein the metal oxide film comprises an element M (M represents Ti, Ga, Y, Zr, La, Ce, Nd, or Hf) and Zn, and
wherein the metal oxide film comprises a portion where x/(x+y) is greater than 0.67 and less than or equal to 0.99 when an atomic ratio of the element M to Zn in a target is represented by M:Zn=x:y.

8. The semiconductor device according to claim 7 ,
wherein the element M is Ga.

9. The semiconductor device according to claim 7 ,
wherein the second oxide semiconductor film comprises a plurality of crystal parts having c-axis alignment, and c-axes of the plurality of crystal parts are aligned in a direction parallel to a normal vector to an upper surface of the second oxide semiconductor film.

10. The semiconductor device according to claim 7 ,
wherein the gate insulating film is in contact with the gate electrode.

11. The semiconductor device according to claim 7 ,
wherein an electron affinity of the second oxide semiconductor film is higher than an electron affinity of the first oxide semiconductor film.

12. An electronic device comprising the semiconductor device according to claim 7 .

13. A semiconductor device comprising:
a first oxide semiconductor film;
a second oxide semiconductor film over the first oxide semiconductor film;
a source electrode over the second oxide semiconductor film;
a drain electrode over the second oxide semiconductor film;
a metal oxide film over the second oxide semiconductor film, the source electrode, and the drain electrode; and
a gate electrode overlapping with the second oxide semiconductor film with a gate insulating film interposed therebetween,
wherein the first oxide semiconductor film comprises a first side surface and a second side surface,
wherein the first side surface is aligned with a side surface of the source electrode,
wherein the second side surface is aligned with a side surface of the drain electrode,
wherein the metal oxide film comprises an element M (M represents Ti, Ga, Y, Zr, La, Ce, Nd, or Hf) and Zn, and
wherein a concentration of an element other than the element M, Zn, and oxygen is less than or equal to 0.1%.

14. The semiconductor device according to claim 13 ,
wherein the element M is Ga.

15. The semiconductor device according to claim 13 ,
wherein the second oxide semiconductor film comprises a plurality of crystal parts having c-axis alignment, and c-axes of the plurality of crystal parts are aligned in a direction parallel to a normal vector to an upper surface of the second oxide semiconductor film.

16. The semiconductor device according to claim 13 ,
wherein the gate insulating film is in contact with the gate electrode.

17. The semiconductor device according to claim 13 ,
wherein an electron affinity of the second oxide semiconductor film is higher than an electron affinity of the first oxide semiconductor film.

18. An electronic device comprising the semiconductor device according to claim 13 .

Assignees

• Semiconductor Energy Lab

Inventors

• Tsubuku Masashi
• Takeuchi Toshihiko
• Yamane Yasumasa
• Oota Masashi

Classifications

• H10P95/90

  Thermal treatments, e.g. annealing or sintering · CPC title

• H10P14/3434

  being oxide semiconductor materials (Group IIB-VIA semiconductor materials H10P14/3424) · CPC title

• H10P14/3426

  Oxides · CPC title

• H10P14/3238

  being insulating materials · CPC title

• H10P14/3234

  being oxide semiconducting materials (Group IIB-VIA semiconductors H10P14/3224) · CPC title