Semiconductor device including oxide semiconductor film and metal oxide film

• US 9,196,739 B2
• Filed: 03/29/2011
• Issued: 11/24/2015
• Est. Priority Date: 04/02/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): PARENDO, KEVIN A
• Application Number:
  US13/074,635
• Publication Number:
  US 20110240993A1
• Time in Patent Office: 1,701 Days
• Field of Search: 257/43, 257/364, 257/410, 257/E29.273, 257/E29.275
• US Class Current: 1/1
• 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

Abstract

A transistor is provided in which the top surface portion of an oxide semiconductor film is provided with a metal oxide film containing a constituent similar to that of the oxide semiconductor film, and an insulating film containing a different constituent from the metal oxide film and the oxide semiconductor film is formed in contact with a surface of the metal oxide film, which is opposite to the surface in contact with the oxide semiconductor film. In addition, the oxide semiconductor film used for the active layer of the transistor is an oxide semiconductor film highly purified to be electrically i-type (intrinsic) through heat treatment in which impurities such as hydrogen, moisture, hydroxyl, and hydride are removed from the oxide semiconductor and oxygen which is one of main component materials of the oxide semiconductor is supplied and is also reduced in a step of removing the impurities.

Claims

1. A semiconductor device comprising:

a gate electrode;

a gate insulating film in contact with the gate electrode;

an oxide semiconductor film provided over the gate insulating film and in a region overlapping with the gate electrode;

a source electrode and a drain electrode in electrical contact with the oxide semiconductor film;

a metal oxide film in contact with the oxide semiconductor film; and

an insulating film in contact with the metal oxide film,

wherein the metal oxide film includes at least one of yttrium and hafnium with a concentration of greater than 0 atomic % and less than or equal to 20 atomic %.

2. The semiconductor device, according to claim 1, wherein the metal oxide film includes an oxide of one or a plurality of metal elements selected from constituent elements of the oxide semiconductor film.

3. The semiconductor device, according to claim 1, wherein an energy gap of the metal oxide film is larger than an energy gap of the oxide semiconductor film.

4. The semiconductor device, according to claim 1, wherein an energy at a bottom of a conduction band of the metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.

5. The semiconductor device, according to claim 1,

wherein the metal oxide film includes GaOx, and

wherein a value of the x is larger than or equal to 1.4 and smaller than or equal to 2.0.

6. The semiconductor device, according to claim 1, wherein a conductive film is formed over the insulating film.

7. The semiconductor device, according to claim 1, wherein the semiconductor device is one selected from the group consisting of a laptop personal computer, a portable information terminal, an e-book reader, a mobile phone, a digital video camera, and a television set.

8. The semiconductor device, according to claim 1, wherein the insulating film is in contact with an entire top surface of the metal oxide film.

9. A semiconductor device comprising:

a gate electrode;

a gate insulating film in contact with the gate electrode;

an oxide semiconductor film provided over the gate insulating film and in a region overlapping with the gate electrode;

a source electrode and a drain electrode in electrical contact with the oxide semiconductor film;

a metal oxide film in contact with the oxide semiconductor film; and

an insulating film in contact with the metal oxide film,

wherein the metal oxide film is thicker than the oxide semiconductor film, and

wherein the metal oxide film includes at least one of yttrium and hafnium with a concentration of greater than 0 atomic % and less than or equal to 20 atomic %.

10. The semiconductor device, according to claim 9, wherein the metal oxide film includes an oxide of one or a plurality of metal elements selected from constituent elements of the oxide semiconductor film.

11. The semiconductor device, according to claim 9, wherein an energy gap of the metal oxide film is larger than an energy gap of the oxide semiconductor film.

12. The semiconductor device, according to claim 9, wherein an energy at a bottom of a conduction band of the metal oxide film is higher than an energy at a bottom of a conduction band of the oxide semiconductor film.

13. The semiconductor device, according to claim 9, wherein the metal oxide film includes GaOx, and

wherein a value of the x is larger than or equal to 1.4 and smaller than or equal to 2.0.

14. The semiconductor device, according to claim 9, wherein a conductive film is formed over the insulating film.

15. The semiconductor device, according to claim 9, wherein the semiconductor device is one selected from the group consisting of a laptop personal computer, a portable information terminal, an e-book reader, a mobile phone, a digital video camera, and a television set.

16. The semiconductor device, according to claim 9, wherein the insulating film is in contact with an entire top surface of the metal oxide film.