Projector including a light source and liquid crystal display device

• US 7,282,737 B2
• Filed: 12/30/2005
• Issued: 10/16/2007
• Est. Priority Date: 09/27/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Isobe, Atsuo, Shibata, Hiroshi
• Primary Examiner(s): NGUYEN, THANH T
• Application Number:
  US11/321,642
• Publication Number:
  US 20060194375A1
• Time in Patent Office: 655 Days
• Field of Search: 257/59, 257/72, 257/296, 257/350
• US Class Current: 257/59
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 2201/40 Arrangements for improving the aperture ratio
• 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 27/1248 with a particular composition or shape of the interlayer dielectric specially adapted to the circuit arrangement
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors

Abstract

To provide a liquid crystal display device having high quality display with a high aperture ratio while securing a sufficient storage capacitor (Cs), and at the same time, by dispersing a load (a pixel writing-in electric current) of a capacitor wiring in a timely manner to effectively reduce the load. A scanning line is formed on a layer that is different from a gate electrode so that the capacitor wiring is arranged in parallel with a signal line. Each pixel is connected to the individually independent capacitor wiring via a dielectric. Therefore, variations in the electric potential of the capacitor wiring caused by a writing-in electric current of adjacent pixels can be avoided, thereby obtaining satisfactory display images.

Claims

1. A projector comprising:

a light source; and

a liquid crystal display device, said liquid crystal display device comprising;

a semiconductor film formed on an insulating surface;

a first insulating film formed on the semiconductor film;

a gate electrode and a first wiring formed on the first insulating film;

a second insulating film formed on the gate electrode and the first wiring;

a second wiring connected to the gate electrode, formed on the second insulating film;

a third insulating film formed on the second wiring; and

a third wiring electrically connected to the semiconductor film on the third insulating film,

wherein the first wiring and the second wiring overlap with the second insulating film interposed therebetween.

2. The projector according to claim 1 wherein a storage capacitor is formed in an overlapping portion between the first wiring and the second wiring with the second insulating film interposed as a dielectric layer of the capacitor.

3. The projector according to claim 1 wherein said first wiring extends in an orthogonal direction to said second wiring.

4. The projector according to claim 1 wherein said third wiring is in contact with source or drain region of said semiconductor film.

5. The projector according to claim 1 further comprising a pixel electrode electrically connected to said semiconductor film over the third insulating film.

6. The projector according to claim 1 wherein said first wiring extends in a direction parallel with said third wiring.

7. A projector comprising:

a light source; and

a liquid crystal display device, said liquid crystal display device comprising;

a semiconductor film formed on an insulating surface;

a first insulating film formed on the semiconductor film;

a gate electrode and a first wiring formed on the first insulating film;

a second insulating film formed on the gate electrode and the first wiring;

a second wiring connected to the gate electrode, formed on the second insulating film;

a third insulating film formed on the second wiring; and

a third wiring electrically connected to the semiconductor film on the third insulating film,

wherein the first wiring and the semiconductor film overlap with the first insulating film interposed therebetween.

8. The projector according to claim 7 wherein said first wiring extends in an orthogonal direction to said second wiring.

9. The projector according to claim 7 wherein a portion of the semiconductor film overlapped with said first wiring is doped with an impurity for giving a p-type or n-type conductivity type thereto.

10. The projector according to claim 7 wherein a storage capacitor is formed in an overlapping portion of the first wiring and the semiconductor film with the first insulating film interposed therebetween as a dielectric film of the capacitor.

11. The projector according to claim 7 wherein said first wiring extends in an orthogonal direction to said second wiring.

12. The projector according to claim 7 wherein said first wiring extends in a direction parallel with said third wiring.

13. The projector according to claim 7 wherein said first wiring is a capacitor wiring.

14. The projector according to claim 7 wherein said second wiring is a scanning line.

15. The projector according to claim 7 wherein said third wiring is a signal line.

16. The projector according to claim 7 wherein said first insulating film is a gate insulating film.

17. The projector according to claim 7 wherein said third wiring is in contact with source or drain region of said semiconductor film.

18. The projector according to claim 7 further comprising a pixel electrode electrically connected to said semiconductor film over the third insulating film.

19. A projector comprising:

a light source; and

a liquid crystal display device, said liquid crystal display device comprising;

a semiconductor film over a substrate;

a first insulating film on the semiconductor film;

a gate electrode and a capacitor wiring;

a second insulating film covering the gate electrode and the capacitor wiring, the second insulating film having a first contact hole;

a scanning line formed on the second insulating film and connected to the gate electrode thought the first contact hole;

a third insulating film on the scanning line, the third insulating film having a second contact hole; and

a signal line electrically connected to the semiconductor film and formed on the third insulating film.

20. The projector according to claim 19 wherein, after forming the first insulating film on the semiconductor film, the second insulating film which is overlapped with the scanning line is partly thinned.

21. The projector according to claim 19 wherein said first insulating film is a gate insulating film.

22. A projector comprising:

a light source; and

a liquid crystal display device, said liquid crystal display device comprising;

a plurality of scanning lines formed over a substrate;

a plurality of signal lines formed over said substrate, extending in an orthogonal relation to said plurality of scanning lines;

a plurality of thin film transistors disposed at intersections of said scanning lines and said signal lines, each of said plurality of thin film transistors comprising a semiconductor layer having a channel forming region and a gate electrode formed over the channel forming region with a gate insulating film interposed therebetween;

a plurality of capacitor lines formed over said semiconductor layer with said gate insulating film interposed therebetween;

a first interlayer insulating film formed over said plurality of thin film transistors and said plurality of capacitor lines wherein said plurality of scanning lines are formed on said first interlayer insulating film and electrically connected to said plurality of thin film transistors through contact holes of said first interlayer insulating film;

a second interlayer insulating film wherein the second interlayer insulating film is formed over said plurality of signal lines; and

a plurality of pixel electrodes formed over said second interlayer insulating film,

wherein said plurality of scanning lines overlap said plurality of capacitor lines with said first interlayer insulating film interposed therebetween to form a plurality of storage capacitors therebetween.

23. A projector comprising:

a light source; and

a liquid crystal display device, said liquid crystal display device comprising;

a plurality of scanning lines formed over a substrate;

a plurality of signal lines formed over said substrate, extending in an orthogonal relation to said plurality of scanning lines;

a plurality of thin film transistors disposed at intersections of said plurality of scanning lines and said plurality of signal lines, each of said plurality of thin film transistors comprising a semiconductor layer having a channel forming region and a gate electrode formed over the channel forming region with a gate insulating film interposed therebetween;

a plurality of capacitor lines formed over said semiconductor layer with said gate insulating film interposed therebetween; and

a plurality of pixel electrodes formed over said substrate and operationally connected to said plurality of thin film transistors,

wherein said plurality of capacitor lines extend in a direction parallel with said plurality of signal lines.