It is an object to provide a memory device where an area occupied by a memory cell is small, and moreover, a memory device where an area occupied by a memory cell is small and a data holding period is long. A memory device includes a bit line, a capacitor, a first insulating layer provided over the bit line and including a groove portion, a semiconductor layer, a second insulating layer in contact with the semiconductor layer, and a word line in contact with the second insulating layer. Part of the semiconductor layer is electrically connected to the bit line in a bottom portion of the groove portion, and another part of the semiconductor layer is electrically connected to one electrode of the capacitor in a top surface of the first insulating layer.
1. A semiconductor device comprising:
an insulator;
an oxide semiconductor film on a side surface of the insulator;
a gate insulating film adjacent to the side surface of the insulator;
a gate electrode adjacent to the oxide semiconductor film;
a first electrode in contact with the oxide semiconductor film at a first level; and
a second electrode in contact with the oxide semiconductor film at a second level that is higher than the first level,
wherein the oxide semiconductor film is provided between the insulator and the gate insulating film,
wherein the gate insulating film is provided between the gate electrode and the oxide semiconductor film,
wherein a top surface of the gate electrode is higher than a bottom surface of the second electrode,
wherein the first electrode and the second electrode are not overlapped with each other, and
wherein the oxide semiconductor film comprises indium, tin, and zinc.
2. The semiconductor device according to claim 1 ,
wherein the insulator comprises an opening,
wherein the oxide semiconductor film, the gate insulating film, and the gate electrode are provided in the opening, and
wherein the second electrode is provided over the insulator.
3. The semiconductor device according to claim 1 , comprising a third electrode between the oxide semiconductor film and an upper surface of the insulator.
4. The semiconductor device according to claim 1 , wherein the gate insulating film is provided over the first electrode.
5. The semiconductor device according to claim 1 , wherein the gate insulating film is provided over the oxide semiconductor film.
6. The semiconductor device according to claim 1 , wherein the gate electrode is provided over the gate insulating film.
7. The semiconductor device according to claim 1 , comprising a capacitor over and electrically connected to the second electrode.
8. The semiconductor device according to claim 1 , comprising a driver circuit portion on a semiconductor substrate, wherein the driver circuit portion is electrically connected to the first electrode.
9. A semiconductor device comprising a transistor, the transistor comprising:
a first electrode;
an oxide semiconductor film over and in contact with the first electrode;
a second electrode over and in contact with the oxide semiconductor film;
a gate electrode adjacent to the oxide semiconductor film; and
a gate insulating film between the oxide semiconductor film and a side surface of the gate electrode,
wherein a top surface of the gate electrode is higher than a bottom surface of the second electrode,
wherein the first electrode and the second electrode are not overlapped with each other, and
wherein the oxide semiconductor film comprises indium, tin, and zinc.
10. The semiconductor device according to claim 9 , comprising an insulator that comprises an opening,
wherein the oxide semiconductor film, the gate insulating film, and the gate electrode are provided in the opening, and
wherein the second electrode is provided over the insulator.
11. The semiconductor device according to claim 10 , comprising a third electrode between the oxide semiconductor film and an upper surface of the insulator.
12. The semiconductor device according to claim 9 , wherein the gate insulating film is provided over the first electrode.
13. The semiconductor device according to claim 9 , wherein the gate insulating film is provided over the oxide semiconductor film.
14. The semiconductor device according to claim 9 , wherein the gate electrode is provided over the gate insulating film.
15. The semiconductor device according to claim 9 , comprising a capacitor over and electrically connected to the second electrode.
16. The semiconductor device according to claim 9 , comprising a driver circuit portion on a semiconductor substrate, wherein the driver circuit portion is electrically connected to the first electrode.