METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

• US 20110233542A1
• Filed: 03/25/2011
• Published: 09/29/2011
• Est. Priority Date: 03/26/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Godo, Hiromichi, Yamazaki, Shunpei
• Granted Patent: US 8,704,219 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• 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

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 can be prevented.

Claims

1. A semiconductor device comprising:

a gate electrode;

a gate insulating film which covers the gate electrode;

a semiconductor film comprising an oxide semiconductor, wherein a region of the semiconductor film overlaps with the gate electrode;

a source electrode and a drain electrode which are in contact with the semiconductor film;

a metal oxide film which is in contact with the semiconductor film and covers the source electrode and the drain electrode; and

an insulating film which covers the metal oxide film.

2. The semiconductor device according to claim 1, wherein the metal oxide film comprises gallium oxide.

3. The semiconductor device according to claim 1, wherein the metal oxide film comprises one of indium and zinc at 0.01 at. % to 5 at. %.

4. The semiconductor device according to claim 1, wherein the oxide semiconductor comprises indium and gallium.

5. The semiconductor device according to claim 1,

wherein the source electrode and the drain electrode comprise a conductive material whose work function is 3.9 eV or more.

6. The semiconductor device according to claim 1,

wherein the source electrode and the drain electrode comprise one of tungsten nitride and titanium nitride.

7. A semiconductor device comprising:

a gate electrode;

a gate insulating film over the gate electrode;

a semiconductor film comprising an oxide semiconductor, wherein a region of the semiconductor film overlaps with the gate electrode;

a source electrode and a drain electrode which are in contact with the semiconductor film;

a metal oxide film which is in contact with the semiconductor film and overlaps with the source electrode and the drain electrode; and

an insulating film over and in contact with the metal oxide film.

8. The semiconductor device according to claim 7, wherein the metal oxide film comprises gallium oxide.

9. The semiconductor device according to claim 7, wherein the metal oxide film comprises one of indium and zinc at 0.01 at. % to 5 at. %.

10. The semiconductor device according to claim 7, wherein the oxide semiconductor comprises indium and gallium.

11. The semiconductor device according to claim 7,

wherein the source electrode and the drain electrode comprise a conductive material whose work function is 3.9 eV or more.

12. The semiconductor device according to claim 7,

wherein the source electrode and the drain electrode comprise one of tungsten nitride and titanium nitride.

13. A method for manufacturing a semiconductor device, comprising the steps of:

forming a gate electrode over a substrate;

forming a gate insulating film which covers the gate electrode;

forming a semiconductor film comprising an oxide semiconductor over the gate electrode with the gate insulating film interposed therebetween, wherein a region of the semiconductor film overlaps with the gate electrode;

forming a source electrode and a drain electrode over the semiconductor film;

forming a metal oxide film which covers the semiconductor film, the source electrode, and the drain electrode;

forming an insulating film which covers the metal oxide film; and

performing heat treatment on the semiconductor film.

14. The method for manufacturing a semiconductor device, according to claim 13, wherein the metal oxide film comprises gallium oxide.

15. The method for manufacturing a semiconductor device, according to claim 13, wherein the oxide semiconductor comprises indium and gallium.

16. The method for manufacturing a semiconductor device, according to claim 13, wherein the metal oxide film comprises one of indium and zinc at 0.01 at. % to 5 at. %.

17. The method for manufacturing a semiconductor device, according to claim 13, wherein the heat treatment is performed at 450°

C. to 600°

C. inclusive.