PROTECTION CIRCUIT, SEMICONDUCTOR DEVICE, PHOTOELECTRIC CONVERSION DEVICE, AND ELECTRONIC DEVICE

• US 20100202090A1
• Filed: 01/26/2010
• Published: 08/12/2010
• Est. Priority Date: 02/09/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: SHISHIDO, Hideaki, FUKUOKA, Osamu
• Granted Patent: US 8,749,930 B2
• Time in Patent Office: Days
• US Class Current: 361/54
• CPC Class Codes: H01L 27/0255 using diodes as protective elements
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO

Abstract

It is an object to provide a protection circuit and a semiconductor device to which a countermeasure against ESD is applied. The protection circuit includes a signal line electrically connected to an integrated circuit; a first diode provided between the signal line and a first power supply line; a second diode provided in parallel to the first diode; and a third diode provided between the first power supply line and a second power supply line. The first diode is a diode formed by diode-connecting a transistor, and the second diode is a diode having a PIN junction or a PN junction. The protection circuit is particularly effective when applied to a semiconductor device manufactured using a thin film transistor.

Claims

1. A protection circuit comprising:

a signal line electrically connected to an integrated circuit;

a first diode provided between the signal line and a first power supply line;

a second diode provided in parallel to the first diode; and

a third diode provided between the first power supply line and a second power supply line,

wherein the first diode is formed by diode-connecting a transistor, and

wherein the second diode is having a PIN junction or a PN junction.

2. The protection circuit according to claim 1,

wherein the transistor forming the first diode is formed at the same time as at least one of transistors included in the integrated circuit.

3. The protection circuit according to claim 1,

wherein the second diode is a lateral junction diode having the PIN junction or the PN junction which is formed by adding an impurity imparting p-type conductivity and an impurity imparting n-type conductivity to a semiconductor layer, and

wherein the semiconductor layer is formed at the same time as a semiconductor layer of the transistor.

4. The protection circuit according to claim 3,

wherein the semiconductor layer and the semiconductor layer of the transistor are oxide semiconductor layers.

5. The protection circuit according to claim 1,

wherein the signal line includes a resistor that is provided in series in any path which is electrically connected to the integrated circuit.

6. A semiconductor device comprising the protection circuit according to claim 1, wherein the protection circuit is provided for at least one signal line.

7. A photoelectric conversion device comprising the semiconductor device according to claim 6.

8. An electronic device comprising the semiconductor device according to claim 6.

9. An electronic device comprising the photoelectric conversion device according to claim 7.

10. A protection circuit comprising:

a signal line electrically connected to an integrated circuit;

a thin film transistor provided between the signal line and a first power supply line;

a first diode provided in parallel to the thin film transistor; and

a second diode provided between the first power supply line and a second power supply line,

wherein one of source and drain regions of the thin film transistor is connected to the signal line, the other one of the source and drain regions is connected to the first power supply line, and a gate of the thin film transistor is connected to one of the source and drain regions, and

wherein the first diode is having a PIN junction or a PN junction.

11. The protection circuit according to claim 10,

wherein the thin film transistor is formed at the same times as at least one of transistors included in the integrated circuit.

12. The protection circuit according to claim 10,

wherein the first diode is a lateral junction diode having the PIN junction or the PN junction which is formed by adding an impurity imparting p-type conductivity and an impurity imparting n-type conductivity to a semiconductor layer, and

wherein the semiconductor layer is formed at the same times as a semiconductor layer of the thin film transistor.

13. The protection circuit according to claim 12,

wherein the semiconductor layer and the semiconductor layer of the thin film transistor are oxide semiconductor layers.

14. The protection circuit according to claim 10,

wherein the signal line includes a resistor that is provided in series in any path which is electrically connected to the integrated circuit.

15. A semiconductor device comprising the protection circuit according to claim 10, wherein the protection circuit is provided for at least one signal line.

16. A photoelectric conversion device comprising the semiconductor device according to claim 15.

17. An electronic device comprising the semiconductor device according to claim 15.

18. An electronic device comprising the photoelectric conversion device according to claim 16.