Semiconductor device including semiconductor layer
Disclosed is a semiconductor device comprising a thin film transistor and wirings connected to the thin film transistor, in which the thin film transistor has a channel formation region in an oxide semiconductor layer, and a copper metal is used for at least one of a gate electrode, a source electrode, a drain electrode, a gate wiring, a source wiring, and a drain wiring. The extremely low off current of the transistor with the oxide semiconductor layer contributes to reduction in power consumption of the semiconductor device. Additionally, the use of the copper metal allows the combination of the semiconductor device with a display element to provide a display device with high display quality and negligible defects, which results from the low electrical resistance of the wirings and electrodes formed with the copper metal.
1. A semiconductor device comprising:
a gate electrode;
a first insulating layer over the gate electrode;
a semiconductor layer over the first insulating layer and comprising a region overlapping with the gate electrode;
a first electrode and a second electrode each over and electrically connected to the semiconductor layer; and
a second insulating layer over the first electrode and the second electrode,
wherein:
each of the first electrode and the second electrode comprises:
a first conductive barrier layer; and
a conductive layer comprising copper and comprising a region in contact with an upper surface of the first conductive barrier layer;
the semiconductor layer comprises:
a first region not overlapping with any of the first electrode and the second electrode;
a second region overlapping with the first electrode; and
a third region overlapping with the second electrode;
the first region of the semiconductor layer is positioned between the second region of the semiconductor layer and the third region of the semiconductor layer;
the first region of the semiconductor layer comprises a region in contact with the second insulating layer;
the first region of the semiconductor layer is thinner than the second region of the semiconductor layer and the third region of the semiconductor layer;
a lower end portion of the first conductive barrier layer of the first electrode and a lower end portion of the first conductive barrier layer of the second electrode face each other;
a lower end portion of the conductive layer of the first electrode and a lower end portion of the conductive layer of the second electrode face each other;
a distance between the lower end portion of the first conductive barrier layer of the first electrode and the lower end portion of the first conductive barrier layer of the second electrode is shorter than a distance between the lower end portion of the conductive layer of the first electrode and the lower end portion of the conductive layer of the second electrode;
the second electrode comprises:
a first region overlapping with the gate electrode; and
a second region not overlapping with the gate electrode;
the lower end portion of the first conductive barrier layer of the first electrode is in contact with an upper end portion of the second region of the semiconductor layer; and
the lower end portion of the first conductive barrier layer of the second electrode is in contact with an upper end portion of the third region of the semiconductor layer.
2. The semiconductor device claim 1 , wherein each of the first electrode and the second electrode comprises a region in contact with an upper surface of the semiconductor layer.
3. The semiconductor device claim 1 , wherein the first conductive barrier layer is capable of suppressing diffusion of copper.
4. The semiconductor device claim 1 , wherein the first conductive barrier layer comprises titanium.
5. The semiconductor device claim 1 , wherein the first conductive barrier layer comprises a metal nitride.
6. The semiconductor device claim 1 , wherein each of the first electrode and the second electrode comprises a second conductive barrier layer comprising a region in contact with an upper surface of the conductive layer.
7. The semiconductor device claim 1 , wherein each of the first electrode and the second electrode comprises a region in contact with an end portion of the semiconductor layer.
8. The semiconductor device claim 1 , wherein the semiconductor layer is an oxide semiconductor layer.
9. The semiconductor device claim 1 , wherein the first insulating layer comprises:
a first layer comprising a silicon nitride; and
a second layer over the first layer and comprising a silicon oxide.
10. The semiconductor device claim 1 , wherein the second insulating layer comprises:
a first layer comprising a silicon oxide; and
a second layer over the first layer and comprising a silicon nitride.
11. A semiconductor device comprising:
a gate electrode;
a first insulating layer over the gate electrode;
a semiconductor layer over the first insulating layer and comprising a region overlapping with the gate electrode;
a first electrode and a second electrode each over and electrically connected to the semiconductor layer;
a second insulating layer over the first electrode and the second electrode;
an organic resin layer over the second insulating layer; and
a pixel electrode over the organic resin layer and electrically connected to the second electrode,
wherein:
each of the first electrode and the second electrode comprises:
a first conductive barrier layer; and
a conductive layer comprising copper and comprising a region in contact with an upper surface of the first conductive barrier layer;
the semiconductor layer comprises:
a first region not overlapping with any of the first electrode and the second electrode;
a second region overlapping with the first electrode; and
a third region overlapping with the second electrode;
the first region of the semiconductor layer is positioned between the second region of the semiconductor layer and the third region of the semiconductor layer;
the first region of the semiconductor layer comprises a region in contact with the second insulating layer;
the first region of the semiconductor layer is thinner than the second region of the semiconductor layer and the third region of the semiconductor layer;
a lower end portion of the first conductive barrier layer of the first electrode and a lower end portion of the first conductive barrier layer of the second electrode face each other;
a lower end portion of the conductive layer of the first electrode and a lower end portion of the conductive layer of the second electrode face each other;
a distance between the lower end portion of the first conductive barrier layer of the first electrode and the lower end portion of the first conductive barrier layer of the second electrode is shorter than a distance between the lower end portion of the conductive layer of the first electrode and the lower end portion of the conductive layer of the second electrode; and
the second electrode comprises:
a first region overlapping with the gate electrode;
a second region overlapping with the pixel electrode; and
a third region not overlapping with any of the gate electrode and the pixel electrode.
12. The semiconductor device claim 11 , wherein each of the first electrode and the second electrode comprises a region in contact with an upper surface of the semiconductor layer.
13. The semiconductor device claim 11 , wherein the first conductive barrier layer is capable of suppressing diffusion of copper.
14. The semiconductor device claim 11 , wherein the first conductive barrier layer comprises titanium.
15. The semiconductor device claim 11 , wherein the first conductive barrier layer comprises a metal nitride.
16. The semiconductor device claim 11 , wherein each of the first electrode and the second electrode comprises a second conductive barrier layer comprising a region in contact with an upper surface of the conductive layer.
17. The semiconductor device claim 11 , wherein each of the first electrode and the second electrode comprises a region in contact with an end portion of the semiconductor layer.
18. The semiconductor device claim 11 , wherein the semiconductor layer is an oxide semiconductor layer.
19. The semiconductor device claim 11 , wherein the first insulating layer comprises:
a first layer comprising a silicon nitride; and
a second layer over the first layer and comprising a silicon oxide.
20. The semiconductor device claim 11 , wherein the second insulating layer comprises:
a first layer comprising a silicon oxide; and
a second layer over the first layer and comprising a silicon nitride.
21. A semiconductor device comprising:
a gate electrode;
a first insulating layer over the gate electrode;
a semiconductor layer over the first insulating layer and comprising a region overlapping with the gate electrode;
a first electrode and a second electrode each over and electrically connected to the semiconductor layer;
a second insulating layer over the first electrode and the second electrode;
an organic resin layer over the second insulating layer; and
a pixel electrode over the organic resin layer and electrically connected to the second electrode,
wherein:
each of the first electrode and the second electrode comprises:
a first conductive barrier layer; and
a conductive layer comprising copper and comprising a region in contact with an upper surface of the first conductive barrier layer;
the semiconductor layer comprises:
a first region not overlapping with any of the first electrode and the second electrode;
a second region overlapping with the first electrode; and
a third region overlapping with the second electrode;
the first region of the semiconductor layer is positioned between the second region of the semiconductor layer and the third region of the semiconductor layer;
the first region of the semiconductor layer comprises a region in contact with the second insulating layer;
the first region of the semiconductor layer is thinner than the second region of the semiconductor layer and the third region of the semiconductor layer;
a lower end portion of the first conductive barrier layer of the first electrode and a lower end portion of the first conductive barrier layer of the second electrode face each other;
a lower end portion of the conductive layer of the first electrode and a lower end portion of the conductive layer of the second electrode face each other;
a distance between the lower end portion of the first conductive barrier layer of the first electrode and the lower end portion of the first conductive barrier layer of the second electrode is shorter than a distance between the lower end portion of the conductive layer of the first electrode and the lower end portion of the conductive layer of the second electrode;
the second electrode comprises:
a first region overlapping with the gate electrode;
a second region overlapping with the pixel electrode; and
a third region not overlapping with any of the gate electrode and the pixel electrode;
the first electrode comprises a first region and a second region each overlapping with the semiconductor layer; and
at least part of the second electrode is positioned between the first region of the first electrode and the second region of the first electrode.
22. The semiconductor device claim 21 , wherein each of the first electrode and the second electrode comprises a region in contact with an upper surface of the semiconductor layer.
23. The semiconductor device claim 21 , wherein the first conductive barrier layer is capable of suppressing diffusion of copper.
24. The semiconductor device claim 21 , wherein the first conductive barrier layer comprises titanium.
25. The semiconductor device claim 21 , wherein the first conductive barrier layer comprises a metal nitride.
26. The semiconductor device claim 21 , wherein each of the first electrode and the second electrode comprises a second conductive barrier layer comprising a region in contact with an upper surface of the conductive layer.
27. The semiconductor device claim 21 , wherein each of the first electrode and the second electrode comprises a region in contact with an end portion of the semiconductor layer.
28. The semiconductor device claim 21 , wherein the semiconductor layer is an oxide semiconductor layer.
29. The semiconductor device claim 21 , wherein the first insulating layer comprises:
a first layer comprising a silicon nitride; and
a second layer over the first layer and comprising a silicon oxide.
30. The semiconductor device claim 21 , wherein the second insulating layer comprises:
a first layer comprising a silicon oxide; and
a second layer over the first layer and comprising a silicon nitride.