Semiconductor device to include a first transistor with a silicon channel formation region and a second transistor with an oxide semiconductor channel formation region

• US 9,024,248 B2
• Filed: 09/26/2013
• Issued: 05/05/2015
• Est. Priority Date: 02/12/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kurokawa, Yoshiyuki
• Primary Examiner(s): Le, Que T
• Assistant Examiner(s): WILLIAMS, DON J
• Application Number:
  US14/037,751
• Publication Number:
  US 20140027768A1
• Time in Patent Office: 586 Days
• Field of Search: 250/208.1, 250/214.1, 250/214.R, 348/54, 348/177, 348/191, 348/602, 348/739, 348/761, 348/766, 257/43, 257/53, 257/72, 257/187, 257/207, 257/208, 257/250, 257/257, 257/258, 257/262, 257/282, 257/327, 257/346, 257/369, 257/387, 257/393, 257/410, 438/129, 438/136, 438/142
• US Class Current: 250/214.R
• CPC Class Codes: G01J 1/44 Electric circuits for command of an exposure part G03B7/02
• CPC Class Codes: G01J 2001/4446 Type of detector
• 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 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14614 having a special gate structure
• CPC Class Codes: H01L 27/14616 characterised by the channel of the transistor, e.g. channel having a doping gradient
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 31/032 including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors

Abstract

A semiconductor device including photosensor capable of imaging with high resolution is disclosed. The semiconductor device includes the photosensor having a photodiode, a first transistor, and a second transistor. The photodiode generates an electric signal in accordance with the intensity of light. The first transistor stores charge in a gate thereof and converts the stored charge into an output signal. The second transistor transfers the electric signal generated by the photodiode to the gate of the first transistor and holds the charge stored in the gate of the first transistor. The first transistor has a back gate and the threshold voltage thereof is changed by changing the potential of the back gate.

Claims

1. A semiconductor device comprising a plurality of photosensors, at least one of the plurality of photosensors comprising:

a photodiode; and

first and second transistors each comprising a gate, a first terminal, and a second terminal,

wherein the first terminal of the second transistor is directly connected to the photodiode,

wherein the second terminal of the second transistor is directly connected to the gate of the first transistor,

wherein the first transistor comprises a channel formation region comprising silicon, and

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

2. The semiconductor device according to claim 1, wherein the first transistor further comprises a gate insulating layer.

3. The semiconductor device according to claim 2,

wherein the first transistor further comprises an insulating film and a back gate.

4. The semiconductor device according to claim 1, further comprising a third transistor,

wherein a first terminal of the third transistor is electrically connected to the first terminal of the first transistor.

5. The semiconductor device according to claim 4,

wherein the third transistor comprises a channel formation region comprising silicon.

6. The semiconductor device according to claim 1, further comprising a fourth transistor,

wherein:

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor, and

a second terminal of the fourth transistor is electrically connected to the second terminal of the first transistor.

7. The semiconductor device according to claim 1, further comprising a third transistor and a fourth transistor,

wherein:

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

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor, and

a second terminal of the fourth transistor is electrically connected to the second terminal of the first transistor.

8. The semiconductor device according to claim 1, further comprising a third transistor and a fourth transistor,

wherein:

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

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor, and

a second terminal of the fourth transistor is electrically connected to a second terminal of the third transistor.

9. The semiconductor device according to claim 1, further comprising a fourth transistor,

wherein:

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor, and

a second terminal of the fourth transistor is electrically connected to the first terminal of the first transistor.

10. The semiconductor device according to claim 1,

wherein the one of the plurality of photosensors comprises a display element.

11. An electronic appliance comprising the semiconductor device according to claim 1.

12. A semiconductor device comprising a plurality of photosensors, at least one of the plurality of photosensors comprising:

first to third signal lines;

a photodiode comprising first and second terminals; and

first and second transistors each comprising a gate, a first terminal, and a second terminal,

wherein the first terminal of the second transistor is directly connected to the photodiode,

wherein the second terminal of the second transistor is directly connected to the gate of the first transistor,

wherein the first transistor comprises a channel formation region comprising silicon,

wherein the second transistor comprises a channel formation region comprising an oxide semiconductor, and

wherein;

the first signal line is electrically connected to the first terminal of the photodiode;

the second terminal of the photodiode is electrically connected to the first terminal of the second transistor;

the second signal line is electrically connected to the gate of the second transistor;

the second terminal of the second transistor is electrically connected to the gate of the first transistor; and

the third signal line is electrically connected to the second terminal of the first transistor.

13. The semiconductor device according to claim 12,

wherein the first transistor further comprises a gate insulating layer.

14. The semiconductor device according to claim 13, further comprising a fourth signal line,

wherein:

the first transistor further comprises an insulating film and a back gate; and

the fourth signal line is electrically connected to the back gate.

15. The semiconductor device according to claim 12, further comprising:

fifth and sixth signal lines; and

a third transistor;

wherein;

the fifth signal line is electrically connected to a second terminal of the third transistor;

the sixth signal line is electrically connected to a gate of the third transistor; and

a first terminal of the third transistor is electrically connected to the first terminal of the first transistor.

16. The semiconductor device according to claim 15,

wherein the third transistor comprises a channel formation region comprising silicon.

17. The semiconductor device according to claim 12, further comprising a fourth transistor,

wherein:

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor; and

a second terminal of the fourth transistor is electrically connected to the third signal line.

18. The semiconductor device according to claim 12, further comprising:

fifth and sixth signal lines; and

third and fourth transistors,

wherein;

the fifth signal line is electrically connected to a second terminal of the third transistor;

the sixth signal line is electrically connected to a gate of the third transistor;

a first terminal of the third transistor is electrically connected to the first terminal of the first transistor;

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor; and

a second terminal of the fourth transistor is electrically connected to the third signal line.

19. The semiconductor device according to claim 12, further comprising:

fifth and sixth signal lines; and

third and fourth transistors,

wherein;

the fifth signal line is electrically connected to the first terminal of the first transistor;

the sixth signal line is electrically connected to a gate of the third transistor;

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

a second terminal of the third transistor is electrically connected to the third signal line;

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor; and

a second terminal of the fourth transistor is electrically connected to the third signal line.

20. The semiconductor device according to claim 12, further comprising:

a fifth signal line; and

a fourth transistor,

wherein;

the fifth signal line is electrically connected to the first terminal of the first transistor and a second terminal of the fourth transistor; and

a first terminal of the fourth transistor is electrically connected to the gate of the first transistor.

21. The semiconductor device according to claim 12,

wherein the one of the plurality of photosensors comprises a display element.

22. An electronic appliance comprising the semiconductor device according to claim 12.