Display device and electronic device

1. A display device comprising: a thin film transistor; and a wiring layer in contact with a substrate; wherein said thin film transistor includes a semiconductor layer, a gate electrode disposed so as to be opposed to said semiconductor layer, the gate electrode being different in thickness from said wiring layer, and a gate insulating film between said semiconductor layer and said gate electrode, wherein the gate insulating film is not in contact with the wiring layer, wherein the wiring layer is formed as a separate component from a source and a drain, and wherein the source and the drain are connected to the semiconductor layer, wherein said wiring layer has a multilayer structure comprising an upper layer that is furthest from the substrate, and wherein the upper layer has a film thickness that is the same as a gate film thickness of said gate electrode.

2. The display device according to claim 1 , wherein thickness of said gate electrode is smaller than thickness of said wiring layer.

3. The display device according to claim 1 , wherein said wiring layer has a multilayer structure, and film thickness and constituent material of at least one layer are same as film thickness and constituent material of said gate electrode.

4. The display device according to claim 1 , wherein at least a part of constituent material is different between said wiring layer and said gate electrode.

5. The display device according to claim 1 , wherein at least a part of said wiring layer is formed of a material having lower electric resistance than constituent material of said gate electrode.

6. The display device according to claim 1 , wherein said semiconductor layer is formed by an oxide semiconductor film.

7. The display device according to claim 1 , wherein said semiconductor layer is formed by a crystalline oxide semiconductor.

8. The display device according to claim 1 , wherein said gate electrode and said semiconductor layer are formed by a sputtering method.

9. The display device according to claim 1 , wherein said thin film transistor has a structure formed by laminating said gate electrode, said gate insulating film, said semiconductor layer, and a source electrode and a drain electrode electrically connected to said semiconductor layer in this order from a side of a substrate.

10. The display device according to claim 1 , wherein said thin film transistor has a structure formed by laminating a source electrode and a drain electrode electrically connected to said semiconductor layer, said semiconductor layer, said gate insulating film, and said gate electrode in this order from a side of a substrate.

11. A display device comprising: a thin film transistor; and a wiring layer in contact with a substrate; wherein said thin film transistor includes a semiconductor layer, a gate electrode disposed so as to be opposed to said semiconductor layer, at least a part of constituent material being different between the gate electrode and said wiring layer, and a gate insulating film between said semiconductor layer and said gate electrode, wherein the gate insulating film is not in contact with the wiring layer, wherein said wiring layer has a multilayer structure comprising an upper layer that is furthest from the substrate, and wherein the upper layer has a film thickness that is the same as a gate film thickness of said gate electrode.

12. The display device according to claim 11 , wherein said wiring layer has a multilayer structure, and includes at least one layer formed of a same constituent material with a same film thickness as said gate electrode and one layer formed of a material having lower electric resistance than constituent material of said gate electrode, and wherein the wiring layer is formed as a separate component from a source and a drain, and wherein the source and the drain are connected to the semiconductor layer.

13. An electronic device comprising: a display device; wherein said display device includes a thin film transistor, and a wiring layer in contact with a substrate, and said thin film transistor includes a semiconductor layer, a gate electrode disposed so as to be opposed to said semiconductor layer, the gate electrode being different in thickness from said wiring layer, and a gate insulating film between said semiconductor layer and said gate electrode, wherein the gate insulating film is not in contact with the wiring layer, wherein the wiring layer is formed as a separate component from a source and a drain, and wherein the source and the drain are connected to the semiconductor layer, wherein said wiring layer has a multilayer structure comprising an upper layer that is furthest from the substrate, and wherein the upper layer has a film thickness that is the same as a gate film thickness of said gate electrode.

14. An electronic device comprising: a display device; wherein said display device includes a thin film transistor, and a wiring layer in contact with a substrate, and said thin film transistor includes a semiconductor layer, a gate electrode disposed so as to be opposed to said semiconductor layer, at least a part of constituent material being different between the gate electrode and said wiring layer, and a gate insulating film between said semiconductor layer and said gate electrode, wherein the gate insulating film is not in contact with the wiring layer, wherein said wiring layer has a multilayer structure comprising an upper layer that is furthest from the substrate, and wherein the upper layer has a film thickness that is the same as a gate film thickness of said gate electrode.

15. The device of claim 1 , wherein the wiring layer is laminated to the substrate.

16. The device of claim 1 , wherein the wiring layer is formed by sputtering or chemical vapor deposition.