Metal oxide semiconductor device

• US 9,941,414 B2
• Filed: 08/19/2016
• Issued: 04/10/2018
• Est. Priority Date: 03/26/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): YUSHIN, NIKOLAY K
• Application Number:
  US15/241,113
• Publication Number:
  US 20160359049A1
• Time in Patent Office: 599 Days
• 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 29/42356 Disposition, e.g. buried gate electrode H01L29/42324 and H01L29/4234 take precedence
• 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 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• 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

Abstract

In a transistor including an oxide semiconductor film, a metal oxide film which has a function of preventing electrification and covers a source electrode and a drain electrode is formed in contact with the oxide semiconductor film, and then, heat treatment is performed. Through the heat treatment, impurities such as hydrogen, moisture, a hydroxyl group, or hydride are intentionally removed from the oxide semiconductor film, whereby the oxide semiconductor film is highly purified. By providing the metal oxide film, generation of a parasitic channel on the back channel side of the oxide semiconductor film in the transistor is prevented.

Claims

1. A semiconductor device comprising:

a gate electrode;

a gate insulating film;

an oxide semiconductor film overlapping the gate electrode with the gate insulating film therebetween;

a source electrode and a drain electrode electrically connected to the oxide semiconductor film; and

a metal oxide film over the source electrode and the drain electrode and in contact with a top surface of the oxide semiconductor film,

wherein the oxide semiconductor film contains indium, gallium, and zinc, and

wherein the metal oxide film contains gallium and indium.

2. The semiconductor device according to claim 1, wherein a thickness of the metal oxide film is larger than a thickness of the oxide semiconductor film.

3. The semiconductor device according to claim 1, wherein the oxide semiconductor film is over the gate electrode.

4. The semiconductor device according to claim 1, wherein a difference between a band gap of the metal oxide film and a band gap of the oxide semiconductor film is less than 3.0 eV.

5. The semiconductor device according to claim 1, wherein a hydrogen concentration of the metal oxide film is lower than or equal to a hydrogen concentration of the oxide semiconductor film.

6. The semiconductor device according to claim 1, wherein the metal oxide film is in contact with the gate insulating film.

7. A semiconductor device comprising:

a gate electrode;

a gate insulating film;

an oxide semiconductor film overlapping the gate electrode with the gate insulating film therebetween;

a source electrode and a drain electrode electrically connected to the oxide semiconductor film; and

a metal oxide film over the source electrode and the drain electrode and in contact with a top surface of the oxide semiconductor film,

wherein the oxide semiconductor film contains indium, gallium and zinc, and

wherein the metal oxide film contains gallium and zinc.

8. The semiconductor device according to claim 7, wherein a thickness of the metal oxide film is larger than a thickness of the oxide semiconductor film.

9. The semiconductor device according to claim 7, wherein the oxide semiconductor film is over the gate electrode.

10. The semiconductor device according to claim 7, wherein a difference between a band gap of the metal oxide film and a band gap of the oxide semiconductor film is less than 3.0 eV.

11. The semiconductor device according to claim 7, wherein a hydrogen concentration of the metal oxide film is lower than or equal to a hydrogen concentration of the oxide semiconductor film.

12. The semiconductor device according to claim 7, wherein the metal oxide film is in contact with the gate insulating film.

13. A semiconductor device comprising:

a gate electrode;

a gate insulating film;

an oxide semiconductor film overlapping the gate electrode with the gate insulating film therebetween;

a source electrode and a drain electrode electrically connected to the oxide semiconductor film;

a metal oxide film over the source electrode and the drain electrode and in contact with a top surface of the oxide semiconductor film; and

a pixel electrode electrically connected to the source electrode or the drain electrode through a contact hole in the metal oxide film,

wherein the oxide semiconductor film contains indium, gallium and zinc,

wherein the metal oxide film contains gallium and at least one of indium and zinc, and

wherein a difference between a band gap of the metal oxide film and a band gap of the oxide semiconductor film is less than 3.0 eV.

14. The semiconductor device according to claim 13, wherein a thickness of the metal oxide film is larger than a thickness of the oxide semiconductor film.

15. The semiconductor device according to claim 13, wherein a hydrogen concentration of part of the metal oxide film is lower than or equal to a hydrogen concentration of the oxide semiconductor film.

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