Semiconductor device and method for manufacturing the same
View Patent ↗A semiconductor device having high electric characteristics and in which a capacitor is efficiently formed even if the semiconductor device has a miniaturized structure. In a top-gate (also referred to as staggered) transistor using an oxide semiconductor film as its active layer, a source electrode and a drain electrode has a two-layer structure (a first electrode film and a second electrode film). Then, a capacitor is formed using a film formed using a material and a step similar to those of the first electrode film, a gate insulating film, and a gate electrode. Accordingly, the transistor and the capacitor can be formed through the same process efficiently. Further, the second electrode is connected onto the oxide semiconductor film between a first electrode and a channel formation region of the transistor. Accordingly, resistance between source and drain electrodes can be reduced; therefore, electric characteristics of the semiconductor device can be improved.
1. A semiconductor device comprising a transistor and a capacitor, the transistor comprising:
an oxide semiconductor film over an insulating surface;
a gate insulating film over the oxide semiconductor film;
a gate electrode over the gate insulating film;
a first electrode film covering an end portion of the oxide semiconductor film, and in direct contact with the end portion of the oxide semiconductor film; and
a second electrode film over and in direct contact with the first electrode film, wherein a portion of the second electrode film is in direct contact with a top surface of the oxide semiconductor film,
the capacitor comprising:
a lower electrode film;
an insulating film over the lower electrode film; and
an upper electrode film over the insulating film.
2. The semiconductor device according to claim 1 , further comprising a second transistor under the transistor,
wherein an active layer of the second transistor comprises silicon, germanium, or a compound semiconductor material, and
wherein the second transistor is electrically connected to at least the transistor or the capacitor.
3. The semiconductor device according to claim 2 , wherein the active layer of the second transistor comprises a film obtained using separation of part of a single crystal semiconductor substrate or a compound semiconductor substrate.
4. The semiconductor device according to claim 2 , wherein the second transistor is positioned over a flexible substrate, and wherein the transistor is positioned over the second transistor.
5. The semiconductor device according to claim 1 , wherein the oxide semiconductor film includes indium, gallium and zinc.
6. The semiconductor device according to claim 1 , wherein the first electrode film and the lower electrode film are over and in direct contact with the insulating surface.
7. The semiconductor device according to claim 1 , wherein the insulating film is same as the gate insulating film, and the upper electrode film is same as the gate electrode.
8. The semiconductor device according to claim 1 , wherein the semiconductor device is one selected from the group consisting of a portable personal computer, an e-book reader, a smartphone, a digital video camera and a television set.
9. A semiconductor device comprising a transistor, the transistor comprising:
an oxide semiconductor film over an insulating surface;
a gate insulating film over the oxide semiconductor film;
a gate electrode over the gate insulating film;
a first electrode film covering an end portion of the oxide semiconductor film and in direct contact with the end portion of the oxide semiconductor film; and
a second electrode film over and in direct contact with the first electrode film, wherein a portion of the second electrode film is in direct contact with a top surface of the oxide semiconductor film.
10. The semiconductor device according to claim 9 , further comprising a second transistor under the transistor,
wherein an active layer of the second transistor comprises silicon, germanium, or a compound semiconductor material, and
wherein the second transistor is electrically connected to the transistor.
11. The semiconductor device according to claim 10 , wherein the active layer of the second transistor comprises a film obtained using separation of part of a single crystal semiconductor substrate or a compound semiconductor substrate.
12. The semiconductor device according to claim 10 , wherein the second transistor is positioned over a flexible substrate, and wherein the transistor is positioned over the second transistor.
13. The semiconductor device according to claim 9 , wherein the oxide semiconductor film includes indium, gallium and zinc.
14. The semiconductor device according to claim 9 , wherein the semiconductor device is one selected from the group consisting of a portable personal computer, an e-book reader, a smartphone, a digital video camera and a television set.