SEMICONDUCTOR DEVICE AND METHOD FOR DRIVING THE SAME

• US 20120026774A1
• Filed: 07/20/2011
• Published: 02/02/2012
• Est. Priority Date: 07/29/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: SHIONOIRI, Yutaka
• Granted Patent: US 8,614,910 B2
• Time in Patent Office: Days
• US Class Current: 365/72
• CPC Class Codes: G11C 11/405 with three charge-transfer gates, e.g. MOS transistors, per cell
• CPC Class Codes: G11C 11/4085 Word line control circuits, e.g. word line drivers, - boosters, - pull-up, - pull-down, - precharge
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO

Abstract

An object is to provide a semiconductor device in which lower power consumption is realized by lowering voltage for data writing without increase in types of power supply potentials. Another object is to provide a semiconductor device in which threshold voltage drop of a selection transistor is suppressed without increase in types of power supply potentials for data writing. A diode-connected transistor is electrically connected in series with a word line electrically connected to a gate of an n-channel selection transistor. A capacitor is provided between the word line and a bit line electrically connected to one of a source and a drain of the selection transistor; alternatively, the capacitance between the bit line and the word line is used. In data writing, the timing of selecting the word line is earlier than the timing of selecting the bit line.

Claims

1. A semiconductor device comprising:

a diode;

a first transistor;

a second transistor; and

a functional circuit,

wherein an output terminal of the diode is electrically connected to a first signal line,

wherein one of a source and a drain of the first transistor is electrically connected to the first signal line,

wherein the other of the source and the drain of the first transistor is electrically connected to a reference potential line,

wherein a gate of the second transistor is electrically connected to the first signal line,

wherein one of a source and a drain one of the second transistor is electrically connected to a second signal line, and

wherein the functional circuit is electrically connected to the other of the source and the drain of the second transistor.

2. The semiconductor device according to claim 1,

wherein the diode is a third transistor,

wherein a gate of the third transistor is connected to one of a source and a drain of the third transistor, and

wherein the other of the source and the drain of the third transistor is electrically connected to the first signal line.

3. The semiconductor device according to claim 1, wherein the second transistor is an n-channel transistor.

4. The semiconductor device according to claim 1, wherein a semiconductor layer of the second transistor comprises an oxide semiconductor.

5. The semiconductor device according to claim 1, wherein a current of the second transistor in an off state per 1 μ

m of channel width is 100 zA or lower with a source-drain voltage of 3.5 V at 25°

C.

6. A semiconductor device comprising:

a diode;

a first transistor; and

a memory cell comprising;

a second transistor; and

a functional circuit,

wherein an output terminal of the diode is electrically connected to a first signal line,

wherein one of a source and a drain of the first transistor is electrically connected to the first signal line,

wherein the other of the source and the drain of the first transistor is electrically connected to a reference potential line,

wherein a gate of the second transistor is electrically connected to the first signal line,

wherein one of a source and a drain one of the second transistor is electrically connected to a second signal line, and

wherein the functional circuit is electrically connected to the other of the source and the drain of the second transistor.

7. The semiconductor device according to claim 6,

wherein the diode is a third transistor,

wherein a gate of the third transistor is connected to one of a source and a drain of the third transistor, and

wherein the other of the source and the drain of the third transistor is electrically connected to the first signal line.

8. The semiconductor device according to claim 6, wherein the second transistor is an n-channel transistor.

9. The semiconductor device according to claim 6, wherein a semiconductor layer of the second transistor comprises an oxide semiconductor.

10. The semiconductor device according to claim 6, wherein a current of the second transistor in an off state per 1 μ

m of channel width is 100 zA or lower with a source-drain voltage of 3.5 V at 25°

C.

11. A semiconductor device comprising:

a diode;

a first transistor; and

a pixel comprising;

a second transistor; and

a functional circuit,

wherein an output terminal of the diode is electrically connected to a first signal line,

wherein one of a source and a drain of the first transistor is electrically connected to the first signal line,

wherein the other of the source and the drain of the first transistor is electrically connected to a reference potential line,

wherein a gate of the second transistor is electrically connected to the first signal line,

wherein one of a source and a drain one of the second transistor is electrically connected to a second signal line, and

wherein the functional circuit is electrically connected to the other of the source and the drain of the second transistor.

12. The semiconductor device according to claim 11,

wherein the diode is a third transistor,

wherein a gate of the third transistor is connected to one of a source and a drain of the third transistor, and

wherein the other of the source and the drain of the third transistor is electrically connected to the first signal line.

13. The semiconductor device according to claim 11, wherein the second transistor is an n-channel transistor.

14. The semiconductor device according to claim 11, wherein a semiconductor layer of the second transistor comprises an oxide semiconductor.

15. The semiconductor device according to claim 11, wherein a current of the second transistor in an off state per 1 μ

m of channel width is 100 zA or lower with a source-drain voltage of 3.5 V at 25°

C.

16. A method for driving a semiconductor device,

the semiconductor device comprising:

a diode, an output terminal of the diode electrically connected to a first signal line;

a first transistor, one of a source and a drain of the first transistor electrically connected to the first signal line, the other of the source and the drain of the first transistor electrically connected to a reference potential line; and

a second transistor, a gate of the second transistor electrically connected to the first signal line and one of a source and a drain of the second transistor electrically connected to a second signal line,

the method comprising;

a first step of applying a first potential to an input terminal of the diode to increase a potential of the first signal line to a second potential;

a second step of applying the first potential to the second signal line and charging a capacitance between the first signal line and the second signal line to increase the potential of the first signal line to a third potential, applying the third potential to the gate of the second transistor, and applying the first potential to the one of the source and the drain of the second transistor;

a third step of applying a fourth potential to the input terminal of the diode; and

a fourth step of applying the first potential to a gate of the first transistor to turn on the first transistor and decreasing the potential of the first signal line to the fourth potential to apply the fourth potential to the gate of the second transistor and turn off the second transistor,

wherein the second step is performed after the first step, and

wherein the first potential is higher than a sum of a threshold voltage of the diode and a threshold voltage of the second transistor.

17. The method for driving a semiconductor device, according to claim 16, further comprising a fifth step of applying the fourth potential to the second signal line,

wherein the fifth step is performed after the fourth step.

18. The method for driving a semiconductor device, according to claim 16,

wherein the diode is a third transistor,

wherein a gate of the third transistor is connected to one of a source and a drain of the third transistor, and

wherein the other of the source and the drain of the third transistor is electrically connected to the first signal line.

19. The method for driving a semiconductor device according to claim 16, wherein the second transistor is an n-channel transistor.

20. The method for driving a semiconductor device according to claim 16, wherein a semiconductor layer of the second transistor comprises an oxide semiconductor.

21. The method for driving a semiconductor device according to claim 16, wherein a current of the second transistor in an off state per 1 μ

m of channel width is 100 zA or lower with a source-drain voltage of 3.5 V at 25°

C.

22. A method for driving a semiconductor device comprising:

the semiconductor device comprising;

a diode, an output terminal of the diode electrically connected to a first signal line;

a first transistor, one of a source and a drain of the first transistor electrically connected to the first signal line, the other of the source and the drain of the first transistor electrically connected to a reference potential line;

a second transistor, a gate of the second transistor electrically connected to the first signal line and one of a source and a drain of the second transistor electrically connected to a second signal line; and

a capacitor between the first signal line and the second signal line, the method comprising;

a first step of applying a first potential to an input terminal of the diode to increase a potential of the first signal line to a second potential;

a second step of applying the first potential to the second signal line and charging the capacitor to increase the potential of the first signal line to a third potential, applying the third potential to the gate of the second transistor, and applying the first potential to the one of the source and the drain of the second transistor;

a third step of applying a fourth potential to the input terminal of the diode; and

a fourth step of applying the first potential to a gate of the first transistor to turn on the first transistor and decreasing the potential of the first signal line to the fourth potential to apply the fourth potential to the gate of the second transistor and turn off the second transistor,

wherein the second step is performed after the first step, and

wherein the first potential is higher than a sum of a threshold voltage of the diode and a threshold voltage of the second transistor.

23. The method for driving a semiconductor device, according to claim 22, further comprising a fifth step of applying the fourth potential to the second signal line, wherein the fifth step is performed after the fourth step.

24. The method for driving a semiconductor device, according to claim 22,

wherein the diode is a third transistor,

wherein a gate of the third transistor is connected to one of a source and a drain of the third transistor, and

wherein the other of the source and the drain of the third transistor is electrically connected to the first signal line.

25. The method for driving a semiconductor device according to claim 22, wherein the second transistor is an n-channel transistor.

26. The method for driving a semiconductor device according to claim 22, wherein a semiconductor layer of the second transistor comprises an oxide semiconductor.

27. The method for driving a semiconductor device according to claim 22, wherein a current of the second transistor in an off state per 1 μ

m of channel width is 100 zA or lower with a source-drain voltage of 3.5 V at 25°

C.