Projection TV

• US 6,617,648 B1
• Filed: 02/23/1999
• Issued: 09/09/2003
• Est. Priority Date: 02/25/1998
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ohtani, Hisashi, Hayakawa, Masahiko, Yamazaki, Shunpei
• Primary Examiner(s): Ngô , Ngân V.
• Application Number:
  US09/255,778
• Time in Patent Office: 1,659 Days
• Field of Search: 257/59, 257/72, 257/350, 257/296
• US Class Current: 257/350
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/66757 Lateral single gate single channel transistors with non-inverted structure, i.e. the channel layer is formed before the gate
• 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 29/78675 with normal-type structure, e.g. with top gate
• CPC Class Codes: H01L 29/78678 with inverted-type structure, e.g. with bottom gate

Abstract

Thin-film transistors constituting a liquid crystal module have a channel forming region that is a crystal structural body in which a plurality of rod-like or flat-rod-like crystals are arranged in a particular direction. In the thin-film transistors, deteriorations in device characteristics due to hot carrier injection or the like can be prevented effectively when the temperature is in a range of 80° C.-250° C. (preferably 100° C.-200° C.). Therefore, a projection TV that is very high in reliability can be realized.

Claims

1. A projection TV having at least an optical system and at least one liquid crystal module, said liquid crystal module having a plurality of thin-film transistors formed over a substrate having an insulating surface,

wherein each of said thin-film transistors has a channel forming region that is a crystal structural body in which a plurality of rod-like or flat-rod-like crystals are arranged approximately parallel with each other in a particular direction, and

wherein said thin-film transistors have an operation temperature of 80°

C.-250°

C.

2. The projection TV according to claim 1, wherein a video signal to be processed in the liquid crystal module is a digital signal.

3. The projection TV according to claim 1, wherein a liquid crystal material that is sealed in the liquid crystal module has a clearing point that is 100°

C. or more.

4. The projection TV according to claim 1, wherein the channel forming region contains one or a plurality of elements selected from the group consisting of Ni, Ge, Co, Fe, Pd, Pt, Cu, and Au at a concentration of 5×

10¹⁷ atoms/cm³ or less.

5. The projection TV according to claim 1, wherein the channel forming region is fully depleted in an on-state.

6. The projection TV according to claim 1, wherein the channel forming region is heated by self-heating in an on-state.

7. The projection TV according to claim 6, wherein the channel forming region has a channel width that is 100 μ

m or more.

8. The projection TV according to claim 6, wherein a channel length L and a channel width W of the channel forming region satisfy a relationship L/W≦

0.01.

9. The projection TV according to claim 1, wherein an image displayed on the liquid crystal module is projected, from inside, onto a screen that is provided inside a main body.

10. A projection TV having at least an optical system and at least one liquid crystal module, said liquid crystal module having a plurality of thin-film transistors formed over a substrate having an insulating surface,

wherein each of said thin-film transistors has a channel forming region that is a crystal structural body in which a plurality of rod-like or flat-rod-like crystals are arranged approximately parallel with each other in a particular direction and crystal lattices are continuous at most of grain boundaries, and

wherein said thin-film transistors have an operation temperature of 80°

C.-250°

C.

11. The projection TV according to claim 10, wherein a video signal to be processed in the liquid crystal module is a digital signal.

12. The projection TV according to claim 10, wherein a liquid crystal material that is sealed in the liquid crystal module has a clearing point that is 100°

C. or more.

13. The projection TV according to claim 10, wherein the channel forming region contains one or a plurality of elements selected from the group consisting of Ni, Ge, Co, Fe, Pd, Pt, Cu, and Au at a concentration of 5 ×

10¹⁷ atoms/cm³ or less.

14. The projection TV according to claim 10, wherein the channel forming region is fully depleted in an on-state.

15. The projection TV according to claim 10, wherein the channel forming region is heated by self-heating in an on-state.

16. The projection TV according to claim 15, wherein the channel forming region has a channel width that is 100 μ

m or more.

17. The projection TV according to claim 15, wherein a channel length L and a channel width W of the channel forming region satisfy a relationship L/W≦

0.01.

18. The projection TV according to claim 10, wherein an image displayed on the liquid crystal module is projected, from inside, onto a screen that is provided inside a main body.

19. A projection-type display device having at least an optical system and at least one liquid crystal module having a pixel matrix circuit, at least one driver circuit, and a logic circuit over a substrate, said pixel matrix circuit comprising:

at least one active layer comprising crystalline semiconductor film over an insulating surface of said substrate, said active layer having at least channel, source, and drain regions of a thin-film transistor;

a gate electrode adjacent to said active layer with an gate insulating film therebetween; and

an auxiliary capacitor composed of a part of said drain region, a capacitor electrode, a layer disposed between said part of the drain region and said capacitor electrode,

wherein said capacitor electrode comprises the same material as the gate electrode and said layer comprises the same material as the gate insulating film.

20. The device according to claim 19, wherein said liquid crystal module is a reflection-type display device.

21. The device according to claim 19, wherein said liquid crystal module further comprising a pixel electrode over said auxiliary capacitor.

22. The device according to claim 19, wherein said projection-type type display is a projection TV.

23. A projection-type display device having at least an optical system and at least one liquid crystal module having a pixel matrix circuit, at least one driver circuit, and a logic circuit over a substrate, said pixel matrix circuit comprising:

at least one active layer of a thin-film transistor comprising crystalline semiconductor film over an insulating surface of said substrate, said active layer having at least channel, source, and drain regions of said thin-film transistor;

a gate electrode adjacent to said active layer with an gate insulating film therebetween;

a drain electrode connected with said drain region disposed over the thin-film transistor; and

a black mask disposed between said thin-film transistor and a, pixel electrode after;

wherein an auxiliary capacitor of the pixel matrix circuit is composed of said drain electrode, said black mask, and a layer disposed between said drain electrode and said black mask.

24. The device according to claim 23, wherein said liquid crystal module is a transmission-type display device.

25. The device according to claim 23, wherein said pixel electrode is a transparent conductive film.

26. The device according to claim 23, wherein said layer comprises silicon nitride.

27. The device according to claim 23, wherein said projection-type display device is a projection TV.