SEMICONDUCTOR DEVICE

• US 20110240993A1
• Filed: 03/29/2011
• Published: 10/06/2011
• 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
• Granted Patent: US 9,196,739 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• 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 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.

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

6. 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.

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

10. The semiconductor device, according to claim 1, wherein the metal oxide film includes gallium oxide.

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

2. A semiconductor device comprising:

a gate electrode;

a gate insulating film in contact with the gate electrode;

a source electrode and a drain electrode provided over the gate insulating film;

an oxide semiconductor film provided over the gate insulating film, the source electrode, and the drain electrode;

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

an insulating film in contact with the metal oxide film.

3. The semiconductor device, according to claim 2, wherein side edges of the oxide semiconductor film in a channel length direction align with side edges of the metal oxide film in a channel length direction.

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

7. The semiconductor device, according to claim 2, wherein an energy gap of the metal oxide film is larger than an energy gap of the oxide semiconductor film.

9. The semiconductor device, according to claim 2, wherein energy at a bottom of a conduction band of the metal oxide film is higher than energy at a bottom of a conduction band of the oxide semiconductor film.

11. The semiconductor device, according to claim 2, wherein the metal oxide film includes gallium oxide.

13. The semiconductor device, according to claim 2, wherein a conductive film is formed over the insulating film.