Light-emitting device

• US 20090008645A1
• Filed: 06/24/2008
• Published: 01/08/2009
• Est. Priority Date: 07/06/2007
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kuwabara, Hideaki, Suzuki, Yukie, Yamazaki, Shunpei
• Granted Patent: US 8,334,537 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• 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 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask
• CPC Class Codes: H01L 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after the gate
• CPC Class Codes: H01L 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• CPC Class Codes: H01L 29/78678 with inverted-type structure, e.g. with bottom gate

Abstract

A method of manufacturing, with high mass productivity, light-emitting devices having highly reliable thin film transistors with excellent electric characteristics is provided. In a light-emitting device having an inverted staggered thin film transistor, the inverted staggered thin film transistor is formed as follows: a gate insulating film is formed over a gate electrode; a microcrystalline semiconductor film which functions as a channel formation region is formed over the gate insulating film; a buffer layer is formed over the microcrystalline semiconductor film; a pair of source and drain regions are formed over the buffer layer; and a pair of source and drain electrodes are formed in contact with the source and drain regions so as to expose a part of the source and drain regions.

Claims

1. A display device comprising:

a gate electrode;

a gate insulating film formed over the gate electrode;

a microcrystalline semiconductor film formed over the gate insulating film;

a buffer layer which is formed over the microcrystalline semiconductor film and has a concave portion;

source and drain regions formed over the buffer layer; and

source and drain electrodes in contact with the source and drain regions, wherein;

a part of the source and drain regions is in contact with the source and drain electrodes;

the other part of the source and drain regions is not in contact with the source and drain electrodes;

the buffer layer is exposed outside the source and drain electrodes; and

end portions of the source and drain regions which are overlapped with the gate electrode are aligned with side faces of the concave portion of the buffer layer.

2. The display device according to claim 1, wherein the buffer layer is formed of an amorphous semiconductor film.

3. The display device according to claim 1, wherein the buffer layer is formed of an amorphous semiconductor film containing nitrogen.

4. The display device according to claim 1, wherein the buffer layer is formed of an amorphous semiconductor film containing hydrogen.

5. The display device according to claim 1, wherein the buffer layer is formed of an amorphous semiconductor film containing fluorine, chlorine, bromine, or iodine.

6. The display device according to claim 1, wherein the display device is a light emitting device.

7. A display device comprising:

a gate electrode;

a gate insulating film formed over the gate electrode;

a microcrystalline semiconductor film formed over the gate insulating film;

a buffer layer which is formed over the microcrystalline semiconductor film and has a concave portion;

source and drain regions formed over the buffer layer; and

source and drain electrodes in contact with the source and drain regions, wherein;

a part of the source and drain regions and a part of the buffer layer are exposed outside the source and drain electrodes; and

end portions of the source and drain regions which are overlapped with the gate electrode are aligned with side faces of the concave portion of the buffer layer.

8. The display device according to claim 7, wherein the buffer layer is formed of an amorphous semiconductor film.

9. The display device according to claim 7, wherein the buffer layer is formed of an amorphous semiconductor film containing nitrogen.

10. The display device according to claim 7, wherein the buffer layer is formed of an amorphous semiconductor film containing hydrogen.

11. The display device according to claim 7, wherein the buffer layer is formed of an amorphous semiconductor film containing fluorine, chlorine, bromine, or iodine.

12. The display device according to claim 7, wherein the display device is a light emitting device.

13. A display device comprising:

a gate electrode;

a gate insulating film formed over the gate electrode;

a microcrystalline semiconductor film formed over the gate insulating film;

a buffer layer which is formed over the microcrystalline semiconductor film and has a concave portion;

source and drain regions formed over the buffer layer;

source and drain electrodes in contact with the source and drain regions;

an insulating film in contact with the source and drain electrodes, a part of the source and drain regions, and a part of the buffer layer; and

a pixel electrode formed over the insulating film and connected to one of the source and drain electrodes through a contact hole formed in the insulating film, wherein;

a part of the source and drain regions is in contact with the source and drain electrodes;

the other part of the source and drain regions is not in contact with the source and drain electrodes;

the buffer layer is exposed outside the source and drain electrodes; and

end portions of the source and drain regions which are overlapped with the gate electrode are aligned with side faces of the concave portion of the buffer layer

14. The display device according to claim 13, wherein the buffer layer is formed of an amorphous semiconductor film.

15. The display device according to claim 13, wherein the buffer layer is formed of an amorphous semiconductor film containing nitrogen.

16. The display device according to claim 13, wherein the buffer layer is formed of an amorphous semiconductor film containing hydrogen.

17. The display device according to claim 13, wherein the buffer layer is formed of an amorphous semiconductor film containing fluorine, chlorine, bromine, or iodine.

18. The display device according to claim 13, wherein the display device is a light emitting device.

19. A display device comprising:

a gate electrode;

a gate insulating film formed over the gate electrode;

a microcrystalline semiconductor film formed over the gate insulating film;

a buffer layer which is formed over the microcrystalline semiconductor film and has a concave portion;

source and drain regions formed over the buffer layer;

source and drain electrodes in contact with the source and drain regions;

an insulating film in contact with the source and drain electrodes, a part of the source and drain regions, and a part of the buffer layer; and

a pixel electrode formed over the insulating film and connected to one of the source and drain electrodes through a contact hole formed in the insulating film, wherein;

a part of the source and drain regions and a part of the buffer layer are exposed outside the source and drain electrodes; and

end portions of the source and drain regions which are overlapped with the gate electrode are aligned with side faces of the concave portion of the buffer layer.

20. The display device according to claim 19, wherein the buffer layer is formed of an amorphous semiconductor film.

21. The display device according to claim 19, wherein the buffer layer is formed of an amorphous semiconductor film containing nitrogen.

22. The display device according to claim 19, wherein the buffer layer is formed of an amorphous semiconductor film containing hydrogen.

23. The display device according to claim 19, wherein the buffer layer is formed of an amorphous semiconductor film containing fluorine, chlorine, bromine, or iodine.

24. The display device according to claim 19, wherein the display device is a light emitting device.

25. A display device comprising:

a gate electrode;

a gate insulating film formed over the gate electrode;

a microcrystalline semiconductor film formed over the gate insulating film;

a buffer layer formed over the microcrystalline semiconductor film;

source and drain regions formed over the buffer layer; and

source and drain electrodes formed on the source and drain regions, wherein;

the source and drain regions extend beyond outer side edges of the source and drain electrodes;

a portion of the buffer layer between the source and drain regions is thinned; and

the buffer layer extends beyond outer side edges of the source and drain regions.

26. The display device according to claim 25, wherein the portion of the buffer layer has side edges aligned with inner side edges of the source and drain regions.

27. The display device according to claim 25, wherein the buffer layer is formed of an amorphous semiconductor film.

28. The display device according to claim 25, wherein the buffer layer is formed of an amorphous semiconductor film containing nitrogen.

29. The display device according to claim 25, wherein the buffer layer is formed of an amorphous semiconductor film containing hydrogen.

30. The display device according to claim 25, wherein the buffer layer is formed of an amorphous semiconductor film containing fluorine, chlorine, bromine, or iodine.

31. The display device according to claim 25, wherein the display device is a light emitting device.