Semiconductor device
A semiconductor device is described, which includes a first transistor, a second transistor, and a capacitor. The second transistor and the capacitor are provided over the first transistor so as to overlap with a gate of the first transistor. A semiconductor layer of the second transistor and a dielectric layer of the capacitor are directly connected to the gate of the first transistor. The second transistor is a vertical transistor, where its channel direction is perpendicular to an upper surface of a semiconductor layer of the first transistor.
1. A semiconductor device comprising:
a first transistor comprising:
a first semiconductor layer; and
a first electrode layer over the first semiconductor layer;
a second transistor comprising:
a second semiconductor layer over the first electrode layer; and
a second electrode layer wherein the second semiconductor layer and the second electrode layer overlap each other in a lateral direction; and
a capacitor comprising:
the first electrode layer; and
a third electrode layer over the first electrode layer with a dielectric layer interposed therebetween,
wherein the second electrode layer includes an opening portion having a circular shape, and
wherein the a surface of the opening portion and the second semiconductor layer overlap each other in the lateral direction with an insulating layer interposed therebetween.
2. The semiconductor device according to claim 1 ,
wherein the second electrode layer is a gate electrode, and
wherein the gate electrode includes a plurality of opening portions having a circular shape.
3. The semiconductor device according to claim 1 ,
wherein the first transistor and the second transistor overlap each other in a vertical direction.
4. The semiconductor device according to claim 1 ,
wherein a channel length direction between source and drain regions of the second transistor is perpendicular to an upper surface of the first semiconductor layer.
5. The semiconductor device according to claim 1 ,
wherein the first transistor and the second transistor overlap each other in a vertical direction, and
wherein a channel length direction between source and drain regions of the second transistor is perpendicular to an upper surface of the first semiconductor layer.
6. The semiconductor device according to claim 1 ,
wherein the second semiconductor layer comprises an oxide semiconductor, and
wherein the first semiconductor layer comprises a material selected from single crystalline silicon, amorphous silicon, and polycrystalline silicon.
7. The semiconductor device according to claim 1 ,
wherein the second transistor and the capacitor overlap each other in a vertical direction.
8. The semiconductor device according to claim 1 ,
wherein a channel region of the first transistor and a channel region of the second transistor overlap each other in a vertical direction.
9. The semiconductor device according to claim 1 ,
wherein the first transistor is located over an insulating surface.
10. An electronic device comprising the semiconductor device according to claim 1 .
11. A semiconductor device comprising:
a gate electrode including an opening portion having a circular shape;
an insulating layer wherein a side surface of the opening portion and the insulating layer overlap each other in a lateral direction;
a semiconductor layer wherein the side surface of the opening portion and the semiconductor layer overlap each other in the lateral direction with the insulating layer interposed therebetween;
a single crystal semiconductor substrate under the gate electrode, the insulating layer and the semiconductor layer; and
an electrode in direct contact with the single crystal semiconductor substrate,
wherein a part of the electrode is over the gate electrode.
12. The semiconductor device according to claim 11 ,
wherein the gate electrode includes a plurality of opening portions having a circular shape.
13. The semiconductor device according to claim 11 ,
wherein the semiconductor layer comprises an oxide semiconductor.
14. The semiconductor device according to claim 11 , further comprising a capacitor over the single crystal semiconductor substrate,
wherein the single crystal semiconductor substrate and the capacitor overlap each other in a vertical direction.
15. An electronic device comprising the semiconductor device according to claim 11 .
16. A semiconductor device comprising:
a gate electrode including an opening portion having a circular shape;
a first insulating layer wherein a side surface of the opening portion and the first insulating layer overlap each other in a lateral direction;
a semiconductor layer wherein the side surface of the opening portion and the semiconductor layer overlap each other in the lateral direction with the first insulating layer interposed therebetween;
a single crystal semiconductor substrate under the gate electrode, the first insulating layer and the semiconductor layer;
a second insulating layer over the gate electrode, the first insulating layer and the semiconductor layer; and
an electrode provided in a contact hole in the second insulating layer, the electrode in direct contact with the single crystal semiconductor substrate.
17. The semiconductor device according to claim 16 ,
wherein the gate electrode includes a plurality of opening portions having a circular shape.
18. The semiconductor device according to claim 16 ,
wherein the semiconductor layer comprises an oxide semiconductor.
19. The semiconductor device according to claim 16 , further comprising a capacitor over the single crystal semiconductor substrate,
wherein the single crystal semiconductor substrate and the capacitor overlap each other in a vertical direction.
20. An electronic device comprising the semiconductor device according to claim 16 .