Semiconductor device

• US 8,674,972 B2
• Filed: 09/02/2011
• Issued: 03/18/2014
• Est. Priority Date: 09/08/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kurokawa, Yoshiyuki, Ikeda, Takayuki
• Primary Examiner(s): Nguyen, Kevin M
• Assistant Examiner(s): Lee, Jr., Kenneth B
• Application Number:
  US13/224,569
• Publication Number:
  US 20120056861A1
• Time in Patent Office: 928 Days
• Field of Search: 345/207, 345/87, 257/43, 257/57, 250/200
• US Class Current: 345/207
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/1251 comprising TFTs having a different architecture, e.g. top- and bottom gate TFTs
• CPC Class Codes: H01L 27/146 Imager structures
• CPC Class Codes: H01L 27/14612 involving a transistor

Abstract

The semiconductor device includes a plurality of photosensors arranged in matrix. The photosensors each include a photoelectric conversion element and an amplifier circuit. A backlight is turned on, an object to be detected is irradiated with light, and the photosensor in a p-th row performs the reset operation and the storage operation. After that, the backlight is turned off, and the photosensor in a (p+1)th row performs the reset operation and the storage operation. Then, the photosensors in all the rows sequentially perform the selection operation. A difference between output signals obtained from the photosensors in adjacent rows is obtained. Using the difference, a captured image of the object is generated and a region where the object exists is detected. The amplifier circuit includes a transistor for holding stored electric charge, in which a channel is formed in an oxide semiconductor layer.

Claims

1. A semiconductor device comprising:

a first photosensor;

a second photosensor;

a first wiring;

a second wiring;

a third wiring;

a fourth wiring;

a fifth wiring;

a sixth wiring; and

a seventh wiring,

wherein each of the first photosensor and the second photosensor comprises a photoelectric conversion element, a first transistor, a second transistor, and a third transistor,

wherein the first wiring is electrically connected to a first electrode of the photoelectric conversion element of the first photosensor,

wherein the second wiring is electrically connected to a first electrode of the photoelectric conversion element of the second photosensor,

wherein the third wiring is electrically connected to a gate of the first transistor of the first photosensor,

wherein the fourth wiring is electrically connected to a gate of the first transistor of the second photosensor,

wherein the fifth wiring is electrically connected to a gate of the second transistor of the first photosensor,

wherein the sixth wiring is electrically connected to a gate of the second transistor of the second photosensor,

wherein a second electrode of the photoelectric conversion element is electrically connected to a first terminal of the first transistor,

wherein a second terminal of the first transistor is electrically connected to a gate of the third transistor,

wherein a first terminal of the second transistor and a first terminal of the third transistor are electrically connected to each other,

wherein the seventh wiring is electrically connected to a second terminal of the second transistor of the first photosensor and a second terminal of the second transistor of the second photosensor,

wherein the first photosensor is configured to perform a first reset operation by supplying a first potential to the first wiring and a second potential to the third wiring and a first storage operation by supplying a third potential to the first wiring and the second potential to the third wiring when a backlight is turned on,

wherein the second photosensor is configured to perform a second reset operation by supplying the first potential to the second wiring and the second potential to the fourth wiring and a second storage operation by supplying the third potential to the second wiring and the second potential to the fourth wiring when the backlight is turned off,

wherein the first photosensor is configured to perform a first selection operation to output a first output signal to the seventh wiring,

wherein the second photosensor is configured to perform a second selection operation to output a second output signal to the seventh wiring, and

wherein the first selection operation and the second selection operation are sequentially performed by sequentially supplying a fourth potential to the fifth wiring and the sixth wiring after the first storage operation and the second storage operation.

2. The semiconductor device according to claim 1, further comprising a display element,

wherein the display element is a liquid crystal element or a light-emitting element.

3. The semiconductor device according to claim 1, further comprising a first display element, a second display element, a third display element, and a fourth display element,

wherein the first photosensor is provided between the first display element and the second display element, and

wherein the first photosensor is provided between the third display element and the fourth display element.

4. A semiconductor device comprising:

a first photosensor;

a second photosensor;

a first wiring;

a second wiring;

a third wiring;

a fourth wiring; and

a fifth wiring,

wherein each of the first photosensor and the second photosensor comprises a photoelectric conversion element, a first transistor, a second transistor, and a third transistor,

wherein the first wiring is electrically connected to a first electrode of the photoelectric conversion element of the first photosensor,

wherein the second wiring is electrically connected to a first electrode of the photoelectric conversion element of the second photosensor,

wherein the third wiring is electrically connected to a gate of the first transistor of the first photosensor,

wherein the fourth wiring is electrically connected to a gate of the first transistor of the second photosensor,

wherein the fifth wiring is electrically connected to a gate of the second transistor of the first photosensor and a gate of the second transistor of the second photosensor,

wherein a second electrode of the photoelectric conversion element is electrically connected to a first terminal of the first transistor,

wherein a second terminal of the first transistor is electrically connected to a gate of the third transistor,

wherein a first terminal of the second transistor and a first terminal of the third transistor are electrically connected to each other,

wherein the first photosensor is configured to perform a first reset operation by supplying a first potential to the first wiring and a second potential to the third wiring and a first storage operation by supplying a third potential to the first wiring and the second potential to the third wiring when a backlight is turned on,

wherein the second photosensor is configured to perform a second reset operation by supplying the first potential to the second wiring and the second potential to the fourth wiring and a second storage operation by supplying the third potential to the second wiring and the second potential to the fourth wiring when the backlight is turned off,

wherein the first photosensor is configured to perform a first selection operation to output a first output signal,

wherein the second photosensor is configured to perform a second selection operation to output a second output signal, and

wherein the first selection operation and the second selection operation are concurrently performed by supplying a fourth potential to the fifth wiring after the first storage operation and the second storage operation.

5. The semiconductor device according to claim 4, further comprising a display element,

wherein the display element is a liquid crystal element or a light-emitting element.

6. The semiconductor device according to claim 4, further comprising a first display element, a second display element, a third display element, and a fourth display element,

wherein the first photosensor is provided between the first display element and the second display element, and

wherein the first photosensor is provided between the third display element and the fourth display element.

7. A semiconductor device comprising:

a first photosensor;

a second photosensor;

a first wiring;

a second wiring;

a third wiring;

a fourth wiring;

a fifth wiring;

a sixth wiring; and

a seventh wiring,

wherein each of the first photosensor and the second photosensor comprises a photoelectric conversion element, a first transistor, a second transistor, and a third transistor,

wherein the first wiring is electrically connected to a first electrode of the photoelectric conversion element of the first photosensor,

wherein the second wiring is electrically connected to a first electrode of the photoelectric conversion element of the second photosensor,

wherein the third wiring is electrically connected to a gate of the first transistor of the first photosensor,

wherein the fourth wiring is electrically connected to a gate of the first transistor of the second photosensor,

wherein the fifth wiring is electrically connected to a gate of the second transistor of the first photosensor,

wherein the sixth wiring is electrically connected to a gate of the second transistor of the second photosensor,

wherein a second electrode of the photoelectric conversion element is electrically connected to a first terminal of the first transistor,

wherein a second terminal of the first transistor is electrically connected to a gate of the third transistor,

wherein a first terminal of the second transistor and a first terminal of the third transistor are electrically connected to each other,

wherein the seventh wiring is electrically connected to a second terminal of the second transistor of the first photosensor and a second terminal of the second transistor of the second photosensor,

wherein the first photosensor is configured to perform a first reset operation by supplying a first potential to the first wiring and a second potential to the third wiring and a first storage operation by supplying a third potential to the first wiring and the second potential to the third wiring when a backlight is turned on,

wherein the second photosensor is configured to perform a second reset operation by supplying the first potential to the second wiring and the second potential to the fourth wiring and a second storage operation by supplying the third potential to the second wiring and the second potential to the fourth wiring when the backlight is turned off,

wherein the first photosensor is configured to perform a first selection operation to output a first output signal to the seventh wiring,

wherein the second photosensor is configured to perform a second selection operation to output a second output signal to the seventh wiring,

wherein the first selection operation and the second selection operation are sequentially performed by sequentially supplying a fourth potential to the fifth wiring and the sixth wiring after the first storage operation and the second storage operation, and

wherein the first transistor comprises a channel formation region comprising an oxide semiconductor layer.

8. The semiconductor device according to claim 7, wherein the oxide semiconductor layer comprises any one of an In—

Sn—

Ga—

Zn—

O-based oxide semiconductor, an In—

Ga—

Zn—

O-based oxide semiconductor, an In—

Sn—

Zn—

O-based oxide semiconductor, an In—

Al—

Zn—

O-based oxide semiconductor, a Sn—

Ga—

Zn—

O-based oxide semiconductor, an Al—

Ga—

Zn—

O-based oxide semiconductor, a Sn—

Al—

Zn—

O-based oxide semiconductor, an In—

Zn—

O-based oxide semiconductor, a Sn—

Zn—

O-based oxide semiconductor, an Al—

Zn—

O-based oxide semiconductor, a Zn—

Mg—

O-based oxide semiconductor, a Sn—

Mg—

O-based oxide semiconductor, an In—

Mg—

O-based oxide semiconductor, an In—

Ga—

O-based oxide semiconductor, an In—

O-based oxide semiconductor, a Sn—

O-based oxide semiconductor, and a Zn—

O-based oxide semiconductor.

9. The semiconductor device according to claim 7, wherein a hydrogen concentration in the oxide semiconductor layer measured by secondary ion mass spectrometry is less than or equal to 5×

10¹⁹ atoms/cm³.

10. The semiconductor device according to claim 7, wherein a sodium concentration in the oxide semiconductor layer measured by secondary ion mass spectrometry is less than or equal to 5×

10¹⁶ atoms/cm³.

11. The semiconductor device according to claim 7, wherein the photoelectric conversion element is a photodiode or a phototransistor.

12. The semiconductor device according to claim 7, further comprising a display element,

wherein the display element is a liquid crystal element or a light-emitting element.

13. The semiconductor device according to claim 7, wherein the backlight comprises at least one of a light source emitting visible light and a light source emitting infrared light.

14. A semiconductor device comprising:

a first photosensor;

a second photosensor;

a first wiring;

a second wiring;

a third wiring;

a fourth wiring; and

a fifth wiring,

wherein each of the first photosensor and the second photosensor comprises a photoelectric conversion element, a first transistor, a second transistor, and a third transistor,

wherein the first wiring is electrically connected to a first electrode of the photoelectric conversion element of the first photosensor,

wherein the second wiring is electrically connected to a first electrode of the photoelectric conversion element of the second photosensor,

wherein the third wiring is electrically connected to a gate of the first transistor of the first photosensor,

wherein the fourth wiring is electrically connected to a gate of the first transistor of the second photosensor,

wherein the fifth wiring is electrically connected to a gate of the second transistor of the first photosensor and a gate of the second transistor of the second photosensor,

wherein a second electrode of the photoelectric conversion element is electrically connected to a first terminal of the first transistor,

wherein a second terminal of the first transistor is electrically connected to a gate of the third transistor,

wherein a first terminal of the second transistor and a first terminal of the third transistor are electrically connected to each other,

wherein the first photosensor is configured to perform a first reset operation by supplying a first potential to the first wiring and a second potential to the third wiring and a first storage operation by supplying a third potential to the first wiring and the second potential to the third wiring when a backlight is turned on,

wherein the second photosensor is configured to perform a second reset operation by supplying the first potential to the second wiring and the second potential to the fourth wiring and a second storage operation by supplying the third potential to the second wiring and the second potential to the fourth wiring when the backlight is turned off,

wherein the first photosensor is configured to perform a first selection operation to output a first output signal,

wherein the second photosensor is configured to perform a second selection operation to output a second output signal,

wherein the first selection operation and the second selection operation are concurrently performed by supplying a fourth potential to the fifth wiring after the first storage operation and the second storage operation, and

wherein the first transistor comprises a channel formation region comprising an oxide semiconductor layer.

15. The semiconductor device according to claim 14, wherein the oxide semiconductor layer comprises any one of an In—

Sn—

Ga—

Zn—

O-based oxide semiconductor, an In—

Ga—

Zn—

O-based oxide semiconductor, an In—

Sn—

Zn—

O-based oxide semiconductor, an In—

Al—

Zn—

O-based oxide semiconductor, a Sn—

Ga—

Zn—

O-based oxide semiconductor, an Al—

Ga—

Zn—

O-based oxide semiconductor, a Sn—

Al—

Zn—

O-based oxide semiconductor, an In—

Zn—

O-based oxide semiconductor, a Sn—

Zn—

O-based oxide semiconductor, an Al—

Zn—

O-based oxide semiconductor, a Zn—

Mg—

O-based oxide semiconductor, a Sn—

Mg—

O-based oxide semiconductor, an In—

Mg—

O-based oxide semiconductor, an In—

Ga—

O-based oxide semiconductor, an In—

O-based oxide semiconductor, a Sn—

O-based oxide semiconductor, and a Zn—

O-based oxide semiconductor.

16. The semiconductor device according to claim 14, wherein a hydrogen concentration in the oxide semiconductor layer measured by secondary ion mass spectrometry is less than or equal to 5×

10¹⁹ atoms/cm³.

17. The semiconductor device according to claim 14, wherein a sodium concentration in the oxide semiconductor layer measured by secondary ion mass spectrometry is less than or equal to 5×

10¹⁶ atoms/cm³.

18. The semiconductor device according to claim 14, wherein the photoelectric conversion element is a photodiode or a phototransistor.

19. The semiconductor device according to claim 14, further comprising a display element,

wherein the display element is a liquid crystal element or a light-emitting element.

20. The semiconductor device according to claim 14, wherein the backlight comprises at least one of a light source emitting visible light and a light source emitting infrared light.