DISPLAY DEVICE

• US 20100084654A1
• Filed: 10/01/2009
• Published: 04/08/2010
• Est. Priority Date: 10/08/2008
• Status: Active Grant

• Current Assignee: Thomson Reuters Global Resources Unlimited Company (The Woodbridge Co. Ltd.)
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: AKIMOTO, Kengo, YAMAZAKI, Shunpei, UOCHI, Hideki, KOMORI, Shigeki, FUTAMURA, Tomoya, KASAHARA, Takahiro
• Granted Patent: US 8,389,988 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: G02F 1/136204 Arrangements to prevent high voltage or static electricity failures
• CPC Class Codes: H01L 27/0248 for electrical or thermal protection, e.g. electrostatic discharge [ESD] protection
• 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 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/0041 characterised by field-effect operation

Abstract

In order to take advantage of the properties of a display device including an oxide semiconductor, a protective circuit and the like having appropriate structures and a small occupied area are necessary. The protective circuit is formed using a non-linear element which includes a gate insulating film covering a gate electrode; a first oxide semiconductor layer over the gate insulating film; a channel protective layer covering a region which overlaps with a channel formation region of the first oxide semiconductor layer; and a first wiring layer and a second wiring layer each of which is formed by stacking a conductive layer and a second oxide semiconductor layer and over the first oxide semiconductor layer. The gate electrode is connected to a scan line or a signal line, the first wiring layer or the second wiring layer is directly connected to the gate electrode.

Claims

1. A display device comprising:

a substrate;

a scan line;

a signal line intersecting with the scan line over the substrate;

a pixel portion in which pixel electrodes are arranged in matrix; and

a first non-linear element provided over the substrate in a region outside the pixel portion,

wherein the pixel portion comprises a thin film transistor in which a channel formation region is formed in a first oxide semiconductor layer,

wherein the thin film transistor comprises;

a gate electrode which is connected to the scan line;

a first wiring layer which is connected to the signal line and the first oxide semiconductor layer; and

a second wiring layer which is connected to the pixel electrode and the first oxide semiconductor layer,

wherein the first non-linear element comprises;

a gate electrode;

a first oxide semiconductor layer formed over the gate electrode of the first non-linear element;

a channel protective layer covering a region which overlaps with a channel formation region of the first oxide semiconductor layer; and

a first wiring layer and a second wiring layer formed over the channel protective layer and the gate electrode of the first non-linear element,

wherein the gate electrode of the first non-linear element is connected to the scan line, and

wherein one of the first wiring layer and the second wiring layer of the first non-linear element is directly connected to a wiring formed with the same layer as the gate electrode of the first non-linear element.

2. The display device according to claim 1 further comprising:

a second non-linear element comprising;

a gate electrode;

a first oxide semiconductor layer formed over the gate electrode of the second non-linear element;

a channel protective layer covering a region which overlaps with a channel formation region of the first oxide semiconductor layer; and

a first wiring layer and a second wiring layer formed over the channel protective layer and the gate electrode of the second non-linear element,

wherein the gate electrode of the second non-linear element is connected to the signal line.

3. The display device according to claim 1, wherein the first non-linear element comprise a combination of oxide semiconductors with different oxygen contents.

4. The display device according to claim 1,

wherein the first wiring layer and the second wiring layer of the first non-linear element is formed by stacking a conductive layer and a second oxide semiconductor layer, and

wherein the conductive layer is in contact with the first oxide semiconductor layer of the first non-linear element with the second oxide semiconductor layer interposed therebetween.

5. The display device according to claim 4,

wherein the first oxide semiconductor layer of the first non-linear element has lower electrical conductivity than the second oxide semiconductor layer.

6. The display device according to claim 4,

wherein the first oxide semiconductor layer and the second oxide semiconductor layer of the first non-linear element contain indium, gallium, and zinc.

7. The display device according to claim 1, wherein the display device is incorporated in one selected from the group consisting of a poster, an advertisement, an electronic book reader, a television device, a digital photo frame, a portable game console, a slot machine and a cellular phone.

8. A display device comprising:

a substrate;

a scan line;

a signal line intersecting with the scan line over the substrate;

a pixel portion in which pixel electrodes are arranged in matrix,

wherein the pixel portion comprises a thin film transistor in which a channel formation region is formed in a first oxide semiconductor layer; and

a first non-linear element provided over the substrate in a region outside the pixel portion,

wherein the thin film transistor comprises;

a gate electrode which is connected to the scan line;

a first wiring layer which is connected to the signal line and the first oxide semiconductor layer, and

a second wiring layer which is connected to the pixel electrode and the first oxide semiconductor layer,

wherein the first non-linear element comprises;

a gate electrode;

a first oxide semiconductor layer formed over the gate electrode of the first non-linear element;

a channel protective layer covering a region which overlaps with a channel formation region of the first oxide semiconductor layer; and

a first wiring layer and a second wiring layer formed over the channel protective layer and the gate electrode of the first non-linear element,

wherein the gate electrode of the first non-linear element is connected to the signal line, and

wherein one of the first wiring layer and the second wiring layer of the first non-linear element is directly connected to a wiring formed with the same layer as the gate electrode of the first non-linear element.

9. The display device according to claim 8, wherein the first non-linear element comprise a combination of oxide semiconductors with different oxygen contents.

10. The display device according to claim 8,

wherein the first wiring layer and the second wiring layer of the first non-linear element is formed by stacking a conductive layer and a second oxide semiconductor layer, and

wherein the conductive layer is in contact with the first oxide semiconductor layer of the first non-linear element with the second oxide semiconductor layer interposed therebetween.

11. The display device according to claim 10,

wherein the first oxide semiconductor layer of the first non-linear element has lower electrical conductivity than the second oxide semiconductor layer.

12. The display device according to claim 10,

wherein the first oxide semiconductor layer and the second oxide semiconductor layer of the first non-linear element contain indium, gallium, and zinc.

13. The display device according to claim 8, wherein the display device is incorporated in one selected from the group consisting of a poster, an advertisement, an electronic book reader, a television device, a digital photo frame, a portable game console, a slot machine and a cellular phone.

14. A display device comprising:

a substrate;

a scan line;

a signal line intersecting with the scan line over the substrate;

a pixel portion in which pixel electrodes are arranged in matrix; and

a protective circuit comprising a first non-linear element formed over the substrate and in a region outside the pixel portion,

wherein the pixel portion comprises a thin film transistor in which a channel formation region is formed in a first oxide semiconductor layer, and

wherein the protective circuit connects the scan line and a common wiring or the signal line and a common wiring to each other,

wherein the thin film transistor comprises;

a gate electrode which is connected to the scan line;

a first wiring layer which is connected to the signal line and the first oxide semiconductor layer; and

a second wiring layer which is connected to the pixel electrode and the first oxide semiconductor layer;

wherein the first non-linear element comprises;

a gate electrode;

a first oxide semiconductor layer;

a channel protective layer covering a region which overlaps with a channel formation region of the first oxide semiconductor layer; and

a first wiring layer and a second wiring layer formed over the channel protective layer and the gate electrode of the first non-linear element,

wherein the gate electrode of the first non-linear element is connected to the scan line, and

wherein one of the first wiring layer and the second wiring layer of the first non-linear element is directly connected to a wiring formed with the same layer as the gate electrode of the first non-linear element.

15. The display device according to claim 14 further comprising:

a second non-linear element comprising;

a gate electrode;

a first oxide semiconductor layer formed over the gate electrode of the second non-linear element;

a channel protective layer covering a region which overlaps with a channel formation region of the first oxide semiconductor layer; and

a first wiring layer and a second wiring layer formed over the channel protective layer and the gate electrode of the second non-linear element,

wherein the gate electrode of the second non-linear element is connected to the signal line.

16. The display device according to claim 14, wherein the first non-linear element comprise a combination of oxide semiconductors with different oxygen contents.

17. The display device according to claim 14,

wherein the first wiring layer and the second wiring layer of the first non-linear element is formed by stacking a conductive layer and a second oxide semiconductor layer, and

wherein the conductive layer is in contact with the first oxide semiconductor layer of the first non-linear element with the second oxide semiconductor layer interposed therebetween.

18. The display device according to claim 17,

wherein the first oxide semiconductor layer of the first non-linear element has lower electrical conductivity than the second oxide semiconductor layer.

19. The display device according to claim 17,

wherein the first oxide semiconductor layer and the second oxide semiconductor layer of the first non-linear element contain indium, gallium, and zinc.

20. The display device according to claim 14, wherein the display device is incorporated in one selected from the group consisting of a poster, an advertisement, an electronic book reader, a television device, a digital photo frame, a portable game console, a slot machine and a cellular phone.

21. A display device comprising:

a substrate;

a scan line;

a signal line intersecting with the scan line over the substrate;

a pixel portion in which pixel electrodes are arranged in matrix;

wherein the pixel portion comprises a thin film transistor in which a channel formation region is formed in a first oxide semiconductor layer; and

a protective circuit comprising a first non-linear element formed over the substrate and in a region outside the pixel portion,

wherein the protective circuit connects the scan line and a common wiring or the signal line and a common wiring to each other,

wherein the thin film transistor comprises;

a gate electrode which is connected to the scan line;

a first wiring layer which is connected to the signal line and the first oxide semiconductor layer; and

a second wiring layer which is connected to the pixel electrode and the first oxide semiconductor layer,

wherein the first non-linear element comprises;

a gate electrode;

a first oxide semiconductor layer;

a channel protective layer covering a region which overlaps with a channel formation region of the first oxide semiconductor layer; and

a first wiring layer and a second wiring layer formed over the channel protective layer and the gate electrode of the first non-linear element;

wherein the gate electrode of the first non-linear element is connected to the signal line, and

wherein one of the first wiring layer and the second wiring layer of the first non-linear element is directly connected to a wiring formed with the same layer as the gate electrode of the first non-linear element.

22. The display device according to claim 21, wherein the first non-linear element comprise a combination of oxide semiconductors with different oxygen contents.

23. The display device according to claim 21,

wherein the first wiring layer and the second wiring layer of the first non-linear element is formed by stacking a conductive layer and a second oxide semiconductor layer, and

wherein the conductive layer is in contact with the first oxide semiconductor layer of the first non-linear element with the second oxide semiconductor layer interposed therebetween.

24. The display device according to claim 23,

wherein the first oxide semiconductor layer of the first non-linear element has lower electrical conductivity than the second oxide semiconductor layer.

25. The display device according to claim 23,

wherein the first oxide semiconductor layer and the second oxide semiconductor layer of the first non-linear element contain indium, gallium, and zinc.

26. The display device according to claim 21, wherein the display device is incorporated in one selected from the group consisting of a poster, an advertisement, an electronic book reader, a television device, a digital photo frame, a portable game console, a slot machine and a cellular phone.