Semiconductor device

• US 8,426,853 B2
• Filed: 12/03/2010
• Issued: 04/23/2013
• Est. Priority Date: 12/04/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Saito, Toshihiko, Uemura, Yuta
• Primary Examiner(s): Thai, Luan C
• Application Number:
  US12/960,013
• Publication Number:
  US 20110133182A1
• Time in Patent Office: 872 Days
• Field of Search: 257/43, 257/E29.296, 257/E21.411
• US Class Current: 257/43
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1218 with a particular composition or structure of the substrate
• 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 27/1266 the substrate on which the devices are formed not being the final device substrate, e.g. using a temporary substrate
• 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: H01L 31/1136 the device being a metal-insulator-semiconductor field-effect transistor

Abstract

An object is to provide a UV sensor with high accuracy, which can be manufactured at low cost and formed over a flexible substrate. A semiconductor device includes a transistor having an oxide semiconductor film, and a voltage source electrically connected to a gate of the transistor, in which a threshold voltage of the transistor is changed by irradiating the oxide semiconductor film with UV rays; a change in the threshold voltage of the transistor is dependent on a wavelength of the UV rays with which the oxide semiconductor film is irradiated, and the voltage source adjusts a voltage output to the gate of the transistor.

Claims

1. A semiconductor device comprising:

a transistor including an oxide semiconductor film; and

a voltage source electrically connected to a gate of the transistor,

wherein a threshold voltage of the transistor is configured to be changed by irradiating the oxide semiconductor film with a UV ray,

wherein a change in the threshold voltage of the transistor is dependent on a wavelength of the UV ray with which the oxide semiconductor film is irradiated, and

wherein the voltage source is configured to adjust a voltage output to the gate of the transistor.

2. The semiconductor device according to claim 1, further comprising an amplifier circuit electrically connected to one of a source and a drain of the transistor.

3. The semiconductor device according to claim 1, wherein a carrier density of the oxide semiconductor film is 5.0×

10¹⁴/cm³ or lower.

4. The semiconductor device according to claim 1, wherein a carrier density of the oxide semiconductor film is 6.0×

10¹⁰/cm³ or lower.

5. The semiconductor device according to claim 1, wherein a wavelength region included in the UV ray is detected by comparing a relationship between the voltage and the threshold voltage of the transistor.

6. A semiconductor device comprising:

a transistor including an oxide semiconductor film; and

a voltage source electrically connected to a gate of the transistor,

wherein off-current of the transistor is configured to be changed by irradiating the oxide semiconductor film with a UV ray,

wherein a change in the off-current of the transistor is dependent on a wavelength of the UV ray with which the oxide semiconductor film is irradiated, and

wherein the voltage source is configured to adjust a voltage output to the gate of the transistor.

7. The semiconductor device according to claim 6, further comprising an amplifier circuit electrically connected to one of a source and a drain of the transistor.

8. The semiconductor device according to claim 6, wherein a carrier density of the oxide semiconductor film is 5.0×

10¹⁴/cm³ or lower.

9. The semiconductor device according to claim 6, wherein a carrier density of the oxide semiconductor film is 6.0×

10¹⁰/cm³ or lower.

10. The semiconductor device according to claim 6, wherein a wavelength region included in the UV ray is detected by comparing a relationship between the voltage and the off-current of the transistor.

11. A semiconductor device comprising:

a pixel portion comprising a first transistor including a first oxide semiconductor film;

a sensor portion comprising;

a second transistor including a second oxide semiconductor film; and

a wiring electrically connected to a gate of the second transistor; and

a voltage source electrically connected to the wiring,

wherein a threshold voltage of the second transistor is configured to be changed by irradiating the second oxide semiconductor film with a UV ray,

wherein a change in the threshold voltage of the second transistor is dependent on a wavelength of the UV ray with which the second oxide semiconductor film is irradiated, and

wherein the voltage source is configured to adjust a voltage output to the gate of the second transistor.

12. The semiconductor device according to claim 11, further comprising an amplifier circuit electrically connected to one of a source and a drain of the second transistor.

13. The semiconductor device according to claim 11,

wherein the sensor portion further comprises a third transistor, and

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

14. The semiconductor device according to claim 11,

wherein the first oxide semiconductor film and the second oxide semiconductor film are formed from the same material.

15. The semiconductor device according to claim 11, wherein a carrier density of the first oxide semiconductor film is 5.0×

10¹⁴/cm³ or lower.

16. The semiconductor device according to claim 11, wherein a carrier density of the first oxide semiconductor film is 6.0×

10¹⁰/cm³ or lower.

17. The semiconductor device according to claim 11, wherein a wavelength region included in the UV ray is detected by comparing a relationship between the voltage and the threshold voltage of the second transistor.

18. A semiconductor device comprising:

a pixel portion comprising a first transistor including a first oxide semiconductor film;

a sensor portion comprising;

a second transistor including a second oxide semiconductor film; and

a wiring electrically connected to a gate of the second transistor; and

a voltage source electrically connected to the wiring,

wherein off-current of the second transistor is configured to be changed by irradiating the second oxide semiconductor film with a UV ray,

wherein a change in the off-current of the second transistor is dependent on a wavelength of the UV ray with which the second oxide semiconductor film is irradiated, and

wherein the voltage source is configured to adjust a voltage output to the gate of the second transistor.

19. The semiconductor device according to claim 18, further comprising an amplifier circuit electrically connected to one of a source and a drain of the second transistor.

20. The semiconductor device according to claim 18,

wherein the sensor portion further comprises a third transistor, and

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

21. The semiconductor device according to claim 18,

wherein the first oxide semiconductor film and the second oxide semiconductor film are formed from the same material.

22. The semiconductor device according to claim 18, wherein a carrier density of the first oxide semiconductor film is 5.0×

10¹⁴/cm³ or lower.

23. The semiconductor device according to claim 18, wherein a carrier density of the first oxide semiconductor film is 6.0×

10¹⁰/cm³ or lower.

24. The semiconductor device according to claim 18, wherein a wavelength region included in the UV ray is detected by comparing a relationship between the voltage and the off-current of the second transistor.