Liquid crystal display device and electronic appliance

• US 8,537,318 B2
• Filed: 10/21/2010
• Issued: 09/17/2013
• Est. Priority Date: 06/02/2006
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime
• Primary Examiner(s): Ullah, Akm Enayet
• Application Number:
  US12/909,237
• Publication Number:
  US 20110037917A1
• Time in Patent Office: 1,062 Days
• Field of Search: 349/43, 349 49- 53, 349141-143
• US Class Current: 349/141
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133502 Antiglare, refractive index matching layers
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G02F 1/1343 Electrodes reflective electrodes G02F1/133553
• CPC Class Codes: G02F 1/134318 having a patterned common electrode
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• 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 1/136231 for reducing the number of lithographic steps
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/124 interdigital
• CPC Class Codes: G02F 2201/50 : Protective arrangements
• CPC Class Codes: G09G 2310/024 : Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2320/0252 : Improving the response speed
• CPC Class Codes: G09G 2340/16 : Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/342 : using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3648 : using an active matrix G09G3/367 - G09G3/3696 take precedence
• 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 27/1225 : with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO

Abstract

A pixel electrode or a common electrode is a light-transmissive conductive film; therefore, it is formed of ITO conventionally. Accordingly, the number of manufacturing steps and masks, and manufacturing cost have been increased. An object of the present invention is to provide a semiconductor device, a liquid crystal display device, and an electronic appliance each having a wide viewing angle, less numbers of manufacturing steps and masks, and low manufacturing cost compared with a conventional device. A semiconductor layer of a transistor, a pixel electrode, and a common electrode of a liquid crystal element are formed in the same step.

Claims

1. A liquid crystal display device comprising:

a first substrate;

a semiconductor film comprising a channel formation region over the first substrate;

a gate electrode adjacent to the channel formation region with a gate insulating film interposed between the semiconductor film and the gate electrode;

a pixel electrode over the first substrate;

a conductive film over the pixel electrode;

a first insulating film over the pixel electrode;

a second insulating film over the first insulating film;

a common electrode over the second insulating film;

a liquid crystal over the common electrode; and

a second substrate over the liquid crystal,

wherein the conductive film is electrically connected to the pixel electrode and the conductive film is electrically connected to the semiconductor film.

2. The liquid crystal display device according to claim 1, wherein the conductive film comprises molybdenum.

3. The liquid crystal display device according to claim 1, wherein the first insulating film comprises silicon nitride.

4. The liquid crystal display device according to claim 1, wherein the common electrode comprises silicon.

5. The liquid crystal display device according to claim 1, wherein the channel formation region of the semiconductor film does not overlap the common electrode.

6. The liquid crystal display device according to claim 1, wherein the pixel electrode and the common electrode overlap each other at least partially.

7. The liquid crystal display device according to claim 1,

wherein the common electrode comprises a first slit and a second slit, and

wherein a long side of the first slit and a long side of the second slit are aligned along different directions.

8. The liquid crystal display device according to claim 1,

wherein the common electrode has a herring-bone structure, and

wherein the common electrode includes a plurality of slits in multiple directions.

9. The liquid crystal display device according to claim 1, wherein the pixel electrode does not comprise a slit.

10. The liquid crystal display device according to claim 1, wherein the pixel electrode and the common electrode have transparent characteristic.

11. The liquid crystal display device according to claim 1,

wherein the liquid crystal display device is configured so that orientation of the liquid crystal is controlled by an electric field generated by a voltage applied between the pixel electrode and the common electrode.

12. The liquid crystal display device according to claim 1, wherein the pixel electrode is in contact with the first substrate.

13. The liquid crystal display device according to claim 1, wherein the gate electrode is located under the gate insulating film.

14. An electronic device comprising the liquid crystal display device according to claim 1.

15. An electronic device comprising an antenna, a battery, and the liquid crystal display device according to claim 1,

wherein the liquid crystal display device is electrically connected to the antenna and the battery.

16. A portable information terminal comprising an operating key and the liquid crystal display device according to claim 1.

17. A liquid crystal display device comprising:

a first substrate;

a semiconductor film comprising a channel formation region over the first substrate;

a gate electrode adjacent to the channel formation region with a gate insulating film interposed between the semiconductor film and the gate electrode;

a pixel electrode over the first substrate

a conductive film over the semiconductor film;

a first insulating film over the pixel electrode;

a second insulating film over the first insulating film;

a common electrode over the second insulating film;

a liquid crystal over the common electrode; and

a second substrate over the liquid crystal,

wherein the conductive film is electrically connected to the pixel electrode,

wherein the channel formation region of the semiconductor film does not overlap the pixel electrode.

18. The liquid crystal display device according to claim 17, wherein the conductive film comprises molybdenum.

19. The liquid crystal display device according to claim 17, wherein the first insulating film comprises silicon nitride.

20. The liquid crystal display device according to claim 17, wherein the common electrode comprises silicon.

21. The liquid crystal display device according to claim 17, wherein the channel formation region of the semiconductor film does not overlap the common electrode.

22. The liquid crystal display device according to claim 17, wherein the pixel electrode and the common electrode overlap each other at least partially.

23. The liquid crystal display device according to claim 17,

wherein the common electrode comprises a first slit and a second slit, and

wherein a long side of the first slit and a long side of the second slit are aligned along different directions.

24. The liquid crystal display device according to claim 17,

wherein the common electrode has a herring-bone structure, and

wherein the common electrode includes a plurality of slits in multiple directions.

25. The liquid crystal display device according to claim 17, wherein the pixel electrode does not comprise a slit.

26. The liquid crystal display device according to claim 17, wherein the pixel electrode and the common electrode have transparent characteristic.

27. The liquid crystal display device according to claim 17,

wherein the liquid crystal display device is configured so that orientation of the liquid crystal is controlled by an electric field generated by a voltage applied between the pixel electrode and the common electrode.

28. The liquid crystal display device according to claim 17, wherein the pixel electrode is in contact with the first substrate.

29. The liquid crystal display device according to claim 17, wherein the gate electrode is located under the gate insulating film.

30. An electronic device comprising the liquid crystal display device according to claim 17.

31. An electronic device comprising an antenna, a battery, and the liquid crystal display device according to claim 17,

wherein the liquid crystal display device is electrically connected to the antenna and the battery.

32. A portable information terminal comprising an operating key and the liquid crystal display device according to claim 17.