Logic circuit and semiconductor device
A logic circuit includes a thin film transistor having a channel formation region formed using an oxide semiconductor, and a capacitor having terminals one of which is brought into a floating state by turning off the thin film transistor. The oxide semiconductor has a hydrogen concentration of 5×10 19 (atoms/cm 3 ) or less and thus substantially serves as an insulator in a state where an electric field is not generated. Therefore, off-state current of a thin film transistor can be reduced, leading to suppressing the leakage of electric charge stored in a capacitor, through the thin film transistor. Accordingly, a malfunction of the logic circuit can be prevented. Further, the excessive amount of current which flows in the logic circuit can be reduced through the reduction of off-state current of the thin film transistor, resulting in low power consumption of the logic circuit.
1. A semiconductor device comprising:
a transistor comprising a first terminal, a second terminal and a gate terminal;
a logic circuit comprising a first output terminal, the first output terminal being electrically connected to the first terminal; and
a capacitor,
wherein the gate terminal is electrically connected to a line,
wherein one terminal of the capacitor is electrically connected to the second terminal and a second output terminal,
wherein each of a source region, a drain region and a channel formation region of the transistor comprises an oxide semiconductor,
wherein the oxide semiconductor includes a plurality of crystals,
wherein the oxide semiconductor comprises indium, gallium and a metal other than indium and gallium,
wherein a hydrogen concentration of the channel formation region is 5×10 19 atoms/cm 3 or less,
wherein the channel formation region is in an oxygen excess state, and
wherein a carrier density of the source region is higher than a carrier density of the channel formation region.
2. The semiconductor device according to claim 1 ,
wherein the logic circuit comprises a second transistor, and
wherein the channel formation region of the second transistor comprises an oxide semiconductor.
3. The semiconductor device according to claim 1 , wherein the other terminal of the capacitor is electrically connected to a low power supply potential line.
4. The semiconductor device according to claim 1 , wherein the oxide semiconductor comprises an In—Ga—Zn—O-based oxide semiconductor.
5. An electronic device comprising the semiconductor device according to claim 1 .
6. The semiconductor device according to claim 1 , wherein the metal is zinc.
7. A semiconductor device comprising:
a transistor comprising a first terminal, a second terminal and a gate terminal;
a register comprising a first output terminal, the first output terminal being electrically connected to the first terminal; and
a capacitor,
wherein the gate terminal is electrically connected to a line,
wherein one terminal of the capacitor is electrically connected to the second terminal and a second output terminal,
wherein each of a source region, a drain region and a channel formation region of the transistor comprises an oxide semiconductor,
wherein the oxide semiconductor includes a plurality of crystals,
wherein the oxide semiconductor comprises indium, gallium and a metal other than indium and gallium,
wherein a hydrogen concentration of the channel formation region is 5×10 19 atoms/cm 3 or less,
wherein the channel formation region is in an oxygen excess state, and
wherein a carrier density of the source region is higher than a carrier density of the channel formation region.
8. The semiconductor device according to claim 7 ,
wherein the register comprises a second transistor, and
wherein the channel formation region of the second transistor comprises an oxide semiconductor.
9. The semiconductor device according to claim 7 , wherein the other terminal of the capacitor is electrically connected to a low power supply potential line.
10. The semiconductor device according to claim 7 , wherein the oxide semiconductor comprises an In—Ga—Zn—O-based oxide semiconductor.
11. The semiconductor device according to claim 7 , wherein the metal is zinc.
12. The semiconductor device according to claim 7 , wherein a carrier density of an oxide semiconductor layer including the source region, the drain region and the channel formation region is 1.45×10 10 /cm 3 or less.
13. An electronic device comprising the semiconductor device according to claim 7 .
14. A semiconductor device comprising:
a transistor comprising a first terminal, a second terminal and a gate terminal;
a logic circuit comprising a first output terminal, the first output terminal being electrically connected to the first terminal; and
a capacitor,
wherein the gate terminal is electrically connected to a line,
wherein one terminal of the capacitor is electrically connected to the second terminal and a second output terminal,
wherein each of a source region, a drain region and a channel formation region of the transistor comprises an oxide semiconductor,
wherein the oxide semiconductor includes a plurality of crystals,
wherein the oxide semiconductor comprises indium, gallium and a metal other than indium and gallium,
wherein a hydrogen concentration of the channel formation region is 5×10 19 atoms/cm 3 or less,
wherein the channel formation region is in an oxygen excess state,
wherein a carrier density of the source region is higher than a carrier density of the channel formation region, and
wherein a carrier density of an oxide semiconductor layer including the source region, the drain region and the channel formation region is 1.45×10 10 /cm 3 or less.
15. The semiconductor device according to claim 14 ,
wherein the logic circuit comprises a second transistor, and
wherein the channel formation region of the second transistor comprises an oxide semiconductor.
16. The semiconductor device according to claim 14 , wherein the other terminal of the capacitor is electrically connected to a low power supply potential line.
17. The semiconductor device according to claim 14 , wherein the oxide semiconductor comprises an In—Ga—Zn—O-based oxide semiconductor.
18. The semiconductor device according to claim 14 , wherein an off-state current of the transistor is 1×10 −13 [A] or less when a voltage between source and drain of the transistor is 10V.
19. The semiconductor device according to claim 14 , wherein the metal is zinc.
20. An electronic device comprising the semiconductor device according to claim 14 .
21. A semiconductor device comprising:
a transistor comprising a first terminal, a second terminal and a gate terminal;
a logic circuit comprising a first output terminal, the first output terminal being electrically connected to the first terminal; and
a capacitor,
wherein the gate terminal is electrically connected to a line,
wherein one terminal of the capacitor is electrically connected to the second terminal and a second output terminal,
wherein each of a source region, a drain region and a channel formation region of the transistor comprises an oxide semiconductor,
wherein the oxide semiconductor includes a plurality of crystals,
wherein the oxide semiconductor comprises indium, gallium and a metal other than indium and gallium,
wherein a hydrogen concentration of the channel formation region is 5×10 19 atoms/cm 3 or less.
22. The semiconductor device according to claim 21 ,
wherein the logic circuit comprises a second transistor, and
wherein the channel formation region of the second transistor comprises an oxide semiconductor.
23. The semiconductor device according to claim 21 , wherein the other terminal of the capacitor is electrically connected to a low power supply potential line.
24. The semiconductor device according to claim 21 , wherein the oxide semiconductor comprises an In—Ga—Zn—O-based oxide semiconductor.
25. The semiconductor device according to claim 21 , wherein the metal is zinc.
26. An electronic device comprising the semiconductor device according to claim 21 .