Thin-film semiconductor device and method for manufacturing the same

1. A thin-film semiconductor device comprising:

a gate electrode above a substrate;

a gate insulating film which covers the gate electrode;

a semiconductor layer above the gate insulating film, the semiconductor layer having a channel region;

a protective layer above the semiconductor layer, the protective layer containing an organic material which includes silicon, oxygen, and carbon;

an interfacial layer in contact with the protective layer between the semiconductor layer and the protective layer, the interfacial layer including carbon as a major component, the carbon originating from the organic material; and

a source electrode and a drain electrode which are electrically connected to the semiconductor layer,

wherein the interfacial layer includes sulfur.

2. The thin-film semiconductor device according to claim 1 ,

wherein a concentration of sulfur included in the interfacial layer is greater than or equal to 5×1019 [atoms/cm3].

3. The thin-film semiconductor device according to claim 1 ,

wherein resistivity of the interfacial layer is greater than or equal to 2×106 [Ω·cm].

4. The thin-film semiconductor device according to claim 1 ,

wherein a thickness of the interfacial layer is from 1 nm to 5 nm.

5. The thin-film semiconductor device according to claim 1 ,

wherein a concentration of sulfur included in the interfacial layer is 100 times or more higher than a concentration of sulfur as impurity included in the semiconductor layer.

6. The thin-film semiconductor device according to claim 1 ,

wherein the interfacial layer has a higher density than the protective layer.

7. The thin-film semiconductor device according to claim 1

wherein a concentration of carbon included in the interfacial layer is 50 times or more higher than a concentration of carbon as impurity included in the semiconductor layer.

8. The thin-film semiconductor device according to claim 1

wherein the semiconductor layer is one of an oxide semiconductor and a crystalline silicon thin film.

9. A method for manufacturing a thin-film semiconductor device, the method comprising:

preparing a substrate;

forming a gate electrode above the substrate;

forming a gate insulating film to cover the gate electrode;

forming a semiconductor layer above the gate insulating film, the semiconductor layer having a channel region;

forming a protective layer above the semiconductor layer by applying an organic material including silicon, oxygen, and carbon;

forming, by baking the protective layer, an interfacial layer, in contact with the protective layer, between the semiconductor layer and the protective layer, the interfacial layer including carbon as a major component, the carbon originating from the organic material; and

forming a source electrode and a drain electrode which are electrically connected to the semiconductor layer,

wherein the interface layer includes sulfur.

10. The method for manufacturing a thin-film semiconductor device according to claim 9 ,

wherein a concentration of sulfur included in the interfacial layer is greater than or equal to 5×1019 [atoms/cm3].

11. The method for manufacturing a thin-film semiconductor device according to claim 9 ,

wherein resistivity of the interfacial layer is greater than or equal to 2×106 [Ω·cm].

12. The method for manufacturing a thin-film semiconductor device according to claim 9 ,

wherein a thickness of the interfacial layer is from 1 nm to 5 nm.

13. The method for manufacturing thin-film semiconductor device according to claim 9 ,

wherein a concentration of sulfur included in the interfacial layer is 100 times or more higher than a concentration of sulfur as impurity included in the semiconductor layer.

14. The method for manufacturing a thin-film semiconductor device according to claim 9 ,

wherein the interfacial layer has a higher density than the protective layer.

15. The method for manufacturing a thin-film semiconductor device according to claim 9 ,

wherein a concentration of carbon included in the interfacial layer is 50 times or more higher than a concentration of carbon as impurity included in the semiconductor layer.

16. The method for manufacturing a thin-film semiconductor device according to claim 9 ,

wherein the semiconductor layer is one of an oxide semiconductor and a crystalline silicon thin film.

17. The method for manufacturing a thin-film semiconductor device according to claim 9 ,

wherein the semiconductor layer is a crystalline silicon thin film,

an organic material included in the protective layer is removed with hydrogen plasma treatment, and

the method further comprises, before the protective layer and the interfacial layer are formed, performing of a hydrogenation process with the hydrogen plasma treatment on the channel region included in the crystalline silicon thin film.

18. A method for manufacturing a thin-film semiconductor device, the method comprising:

preparing a substrate;

forming a gate electrode above the substrate;

forming a gate insulating film to cover the gate electrode;

forming a crystalline silicon thin film above the gate insulating film, the crystalline silicon thin film having a channel region;

foaming a protective layer above the channel region by applying an organic material including carbon; and

forming a source electrode and a drain electrode above the crystalline silicon thin film,

wherein an organic material contained in the protective layer is removed with hydrogen plasma treatment, and

the method further comprises, between the forming of a crystalline silicon thin film and the forming of a protective layer, performing of a hydrogenation process on the crystalline silicon thin film with hydrogen plasma.