Semiconductor device including oxide semiconductor
A more convenient and highly reliable semiconductor device which has a transistor including an oxide semiconductor with higher impact resistance used for a variety of applications is provided. A semiconductor device has a bottom-gate transistor including a gate electrode layer, a gate insulating layer, and an oxide semiconductor layer over a substrate, an insulating layer over the transistor, and a conductive layer over the insulating layer. The insulating layer covers the oxide semiconductor layer and is in contact with the gate insulating layer. In a channel width direction of the oxide semiconductor layer, end portions of the gate insulating layer and the insulating layer are aligned with each other over the gate electrode layer, and the conductive layer covers a channel formation region of the oxide semiconductor layer and the end portions of the gate insulating layer and the insulating layer and is in contact with the gate electrode layer.
1. A semiconductor device comprising a transistor, the transistor comprising:
a gate electrode;
a first insulating layer over the gate electrode;
an oxide semiconductor layer over the gate electrode with the first insulating layer therebetween;
a second insulating layer over the oxide semiconductor layer; and
a conductive layer over the oxide semiconductor layer with the second insulating layer therebetween, wherein the conductive layer is overlapped with the gate electrode,
wherein each of the gate electrode and the conductive layer extends beyond both side edges of the oxide semiconductor layer in a channel width direction of the transistor so that the oxide semiconductor layer is surrounded by the gate electrode, the first insulating layer, the second insulating layer and the conductive layer,
wherein the first insulating layer is in contact with a bottom surface of the oxide semiconductor layer,
wherein the second insulating layer is in contact with a top surface of the oxide semiconductor layer,
wherein the first insulating layer comprises silicon oxide,
wherein the second insulating layer comprises silicon oxide,
wherein the oxide semiconductor layer comprises a portion overlapping with the conductive layer, and
wherein a length of the portion in the channel width direction of the transistor is larger than a length of the portion in a channel length direction of the transistor.
2. The semiconductor device according to claim 1 , wherein the oxide semiconductor layer comprises indium, zinc, oxygen, and a metal element.
3. The semiconductor device according to claim 1 , wherein the semiconductor device is a display device.
4. The semiconductor device according to claim 1 , wherein the transistor is included in a driver circuit.
5. The semiconductor device according to claim 1 , wherein a carrier concentration of a channel formation region of the transistor is lower than 1×10 11 /cm 3 .
6. The semiconductor device according to claim 1 , further comprising:
a source electrode over and electrically connected with the oxide semiconductor layer; and
a drain electrode over and electrically connected with the oxide semiconductor layer.
7. A semiconductor device comprising a transistor, the transistor comprising:
a gate electrode;
a first insulating layer over the gate electrode;
a first oxide semiconductor layer over the gate electrode with the first insulating layer therebetween;
a second oxide semiconductor layer over the gate electrode with the first insulating layer therebetween;
a second insulating layer over the first oxide semiconductor layer and the second oxide semiconductor layer; and
a conductive layer over the first oxide semiconductor layer with the second insulating layer between the first oxide semiconductor layer and the conductive layer, and over the second oxide semiconductor layer with the second insulating layer between the second oxide semiconductor layer and the conductive layer, wherein the conductive layer is overlapped with the gate electrode,
wherein the conductive layer contacts with the gate electrode in a region between the first oxide semiconductor layer and the second oxide semiconductor layer.
8. The semiconductor device according to claim 7 , wherein each of the gate electrode and the conductive layer extends beyond both side edges of the first oxide semiconductor layer and both side edges of the second oxide semiconductor layer in a channel width direction of the transistor so that the first oxide semiconductor layer is surrounded by the gate electrode, the first insulating layer, the second insulating layer and the conductive layer and the second oxide semiconductor layer is surrounded by the gate electrode, the first insulating layer, the second insulating layer and the conductive layer.
9. The semiconductor device according to claim 7 , wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer comprises indium, zinc, oxygen, and a metal element.
10. The semiconductor device according to claim 7 , wherein the semiconductor device is a display device.
11. The semiconductor device according to claim 7 , wherein the transistor is included in a driver circuit.
12. The semiconductor device according to claim 7 , wherein a carrier concentration of a channel formation region of the transistor is lower than 1×10 11 /cm 3 .
13. The semiconductor device according to claim 7 , further comprising:
a source electrode over and electrically connected with the first oxide semiconductor layer and the second oxide semiconductor layer; and
a drain electrode over and electrically connected with the first oxide semiconductor layer and the second oxide semiconductor layer.
14. A semiconductor device comprising a transistor, the transistor comprising:
a gate electrode;
a first insulating layer over the gate electrode;
an oxide semiconductor layer over the gate electrode with the first insulating layer therebetween;
a second insulating layer over the oxide semiconductor layer; and
a conductive layer over the oxide semiconductor layer with the second insulating layer therebetween, wherein the conductive layer is overlapped with the gate electrode,
wherein each of the gate electrode and the conductive layer extends beyond both side edges of the oxide semiconductor layer in a channel width direction of the transistor so that the oxide semiconductor layer is surrounded by the gate electrode, the first insulating layer, the second insulating layer and the conductive layer, and
wherein the conductive layer faces both side surfaces of the oxide semiconductor layer with the second insulating layer therebetween.
15. The semiconductor device according to claim 14 , wherein the oxide semiconductor layer comprises indium, zinc, oxygen, and a metal element.
16. The semiconductor device according to claim 14 , wherein the semiconductor device is a display device.
17. The semiconductor device according to claim 14 , wherein the transistor is included in a driver circuit.
18. The semiconductor device according to claim 14 , wherein a carrier concentration of a channel formation region of the transistor is lower than 1×10 11 /cm 3 .
19. The semiconductor device according to claim 14 , further comprising:
a source electrode over and electrically connected with the oxide semiconductor layer; and
a drain electrode over and electrically connected with the oxide semiconductor layer.
20. A semiconductor device comprising a transistor, the transistor comprising:
a gate electrode;
a first insulating layer over the gate electrode;
a first oxide semiconductor layer over the gate electrode with the first insulating layer therebetween;
a second oxide semiconductor layer over the gate electrode with the first insulating layer therebetween;
a second insulating layer over the first oxide semiconductor layer and the second oxide semiconductor layer; and
a conductive layer over the first oxide semiconductor layer with the second insulating layer between the first oxide semiconductor layer and the conductive layer, and over the second oxide semiconductor layer with the second insulating layer between the second oxide semiconductor layer and the conductive layer, wherein the conductive layer is overlapped with the gate electrode,
wherein the conductive layer contacts with the gate electrode in a region between the first oxide semiconductor layer and the second oxide semiconductor layer,
wherein the conductive layer faces both side surfaces of the first oxide semiconductor layer with the second insulating layer therebetween, and
wherein the conductive layer faces both side surfaces of the second oxide semiconductor layer with the second insulating layer therebetween.
21. The semiconductor device according to claim 20 , wherein each of the gate electrode and the conductive layer extends beyond both side edges of the first oxide semiconductor layer and both side edges of the second oxide semiconductor layer in a channel width direction of the transistor so that the first oxide semiconductor layer is surrounded by the gate electrode, the first insulating layer, the second insulating layer and the conductive layer and the second oxide semiconductor layer is surrounded by the gate electrode, the first insulating layer, the second insulating layer and the conductive layer.
22. The semiconductor device according to claim 20 , wherein each of the first oxide semiconductor layer and the second oxide semiconductor layer comprises indium, zinc, oxygen, and a metal element.
23. The semiconductor device according to claim 20 , wherein the semiconductor device is a display device.
24. The semiconductor device according to claim 20 , wherein the transistor is included in a driver circuit.
25. The semiconductor device according to claim 20 , wherein a carrier concentration of a channel formation region of the transistor is lower than 1×10 11 /cm 3 .
26. The semiconductor device according to claim 20 , further comprising:
a source electrode over and electrically connected with the first oxide semiconductor layer and the second oxide semiconductor layer; and
a drain electrode over and electrically connected with the first oxide semiconductor layer and the second oxide semiconductor layer.