Liquid crystal display device

• US 8,035,781 B2
• Filed: 02/09/2007
• Issued: 10/11/2011
• Est. Priority Date: 03/01/2002
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Tsuji, Yuriko, Eguchi, Shingo
• Primary Examiner(s): Nelms; David
• Assistant Examiner(s): Chung; David
• Application Number:
  US11/672,992
• Publication Number:
  US 20070126959A1
• Time in Patent Office: 1,705 Days
• Field of Search: 349/113, 349/114
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13685 Top gates

Abstract

With an object of providing a transflective type liquid crystal display device having a transparent electrode of an uneven structure formed without particularly increasing steps, in fabricating the transflective type liquid crystal display device, a amorphous transparent conductive film is formed on a substrate, a crystalline portion is formed in the amorphous transparent conductive film to thereby form the transparent conductive film including the crystalline portion, a amorphous portion is removed at a film surface of the transparent conductive film including the crystalline portion to thereby form the transparent conductive film having an uneven shape formed by a remaining crystalline portion at a film surface and a reflecting electrode having the uneven shape is formed by forming a reflective conductive film above the transparent electrode having the uneven shape.

Claims

1. A liquid crystal display device comprising:

a drive circuit over a substrate;

a pixel portion over the substrate and comprising;

a thin film transistor formed over the substrate;

an insulating film formed over the thin film transistor;

a transparent electrode on a surface of the insulating film; and

a reflection electrode formed on the transparent electrode,

wherein the transparent electrode has an uneven surface with respect to the substrate,

wherein an entirety of a bottom surface of the transparent electrode is in contact with the surface of the insulating film,

wherein the uneven surface of the transparent electrode is more uneven than the surface of the insulating film, and

wherein the thin film transistor is electrically connected to the transparent electrode and the reflection electrode.

2. A liquid crystal display device according to claim 1, wherein the transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over the substrate, forming a crystalline portion in the amorphous transparent conductive film, and removing an amorphous portion at a surface of the transparent conductive film including the crystalline portion.

3. A liquid crystal display device according to claim 1, wherein the transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over the substrate, forming a crystalline portion in the amorphous transparent conductive film by sintering, and removing an amorphous portion at a surface of the transparent conductive film including the crystalline portion by etching.

4. A liquid crystal display device according to claim 3, wherein the sintering step is conducted at 150 through 200°

C.

5. A liquid crystal display device according to claim 3, wherein the etching step is conducted by using one or a plural kinds of acidic solution selected from the group constituting of hydrofluoric acid, nitric acid, sulfuric acid, and hydrochloric acid.

6. A liquid crystal display device according to claim 1, wherein the transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over the substrate, forming a crystalline portion in the amorphous transparent conductive film by sintering, polishing the transparent conductive film including the crystalline portion, and etching the transparent conductive film including the crystalline portion.

7. A liquid crystal display device according to claim 6, the polishing step is conducted by CMP.

8. A liquid crystal display device according to claim 1, wherein a rate of an area occupied by the reflection electrode is 50 through 90% of an area occupied by the transparent electrode.

9. A liquid crystal display device according to claim 1, wherein the liquid crystal display device is incorporated into an electronic device selected from the group constituting of a digital still camera, a notebook type personal computer, a mobile computer, a portable image reproducing device having a record medium, a video camera, and a portable telephone.

28. A liquid crystal display device according to claim 1 further comprising:

a liquid crystal over the transparent electrode and the reflection electrode;

a first color filter over the liquid crystal; and

a second color filter over the liquid crystal,

wherein an end portion of the first color filter is overlapped with an end portion of the second color filter.

29. A liquid crystal display device according to claim 1, wherein the drive circuit is a gate signal line drive circuit.

10. A liquid crystal display device comprising:

a drive circuit over a first substrate; and

a pixel portion over the first substrate comprising;

a thin film transistor;

an insulating film formed over the thin film transistor;

a first transparent electrode on a surface of the insulating film;

a reflection electrode formed on the first transparent electrode;

a liquid crystal over the first transparent electrode and the reflection electrode;

a second transparent electrode over the liquid crystal; and

a second substrate over the second transparent electrode,

wherein the first transparent electrode has an uneven surface with respect to the first substrate,

wherein an entirety of a bottom surface of the first transparent electrode is in contact with the surface of the insulating film,

wherein the uneven surface of the first transparent electrode is more uneven than the surface of the insulating film, and

wherein the thin film transistor is electrically connected to the first transparent electrode and the reflection electrode.

11. A liquid crystal display device according to claim 10, wherein the first transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over a substrate, forming a crystalline portion in the amorphous transparent conductive film, and removing an amorphous portion at a surface of the transparent conductive film including the crystalline portion.

12. A liquid crystal display device according to claim 10, wherein the first transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over a substrate, forming a crystalline portion in the amorphous transparent conductive film by sintering, and removing an amorphous portion at a surface of the transparent conductive film including the crystalline portion by etching.

13. A liquid crystal display device according to claim 12, wherein the sintering step is conducted at 150 through 200°

C.

14. A liquid crystal display device according to claim 12, wherein the etching step is conducted by using one or a plural kinds of acidic solution selected from the group constituting of hydrofluoric acid, nitric acid, sulfuric acid, and hydrochloric acid.

15. A liquid crystal display device according to claim 10, wherein the first transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over a substrate, forming a crystalline portion in the amorphous transparent conductive film by sintering, polishing the transparent conductive film including the crystalline portion, and etching the transparent conductive film including the crystalline portion.

16. A liquid crystal display device according to claim 15, the polishing step is conducted by CMP.

17. A liquid crystal display device according to claim 10, wherein a rate of an area occupied by the reflection electrode is 50 through 90% of an area occupied by the first transparent electrode.

18. A liquid crystal display device according to claim 10, wherein the liquid crystal display device is incorporated into an electronic device selected from the group constituting of a digital still camera, a notebook type personal computer, a mobile computer, a portable image reproducing device having a record medium, a video camera, and a portable telephone.

30. A liquid crystal display device according to claim 10, wherein the drive circuit is a gate signal line drive circuit.

19. A liquid crystal display device comprising:

a drive circuit over a first substrate; and

a pixel portion over the first substrate comprising;

a thin film transistor;

an insulating film formed over the thin film transistor;

a first transparent electrode on a surface of the insulating film;

a reflection electrode formed on the first transparent electrode;

a liquid crystal over the first transparent electrode and the reflection electrode;

a second transparent electrode over the liquid crystal;

a first color filter above the second transparent electrode;

a second color filter above the second transparent electrode; and

a second substrate over the first color filter and the second color filter,

wherein the first transparent electrode has an uneven surface with respect to the first substrate,

wherein an entirety of a bottom surface of the first transparent electrode is in contact with the surface of the insulating film,

wherein the uneven surface of the first transparent electrode is more uneven than the surface of the insulating film,

wherein the thin film transistor is electrically connected to the first transparent electrode and the reflection electrode and

wherein an end portion of the first color filter is overlapped with an end portion of the second color filter.

20. A liquid crystal display device according to claim 19, wherein the first transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over a substrate, forming a crystalline portion in the amorphous transparent conductive film, and removing an amorphous portion at a surface of the transparent conductive film including the crystalline portion.

21. A liquid crystal display device according to claim 19, wherein the first transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over a substrate, forming a crystalline portion in the amorphous transparent conductive film by sintering, and removing an amorphous portion at a surface of the transparent conductive film including the crystalline portion by etching.

22. A liquid crystal display device according to claim 21, wherein the sintering step is conducted at 150 through 200°

C.

23. A liquid crystal display device according to claim 21, wherein the etching step is conducted by using one or a plural kinds of acidic solution selected from the group constituting of hydrofluoric acid, nitric acid, sulfuric acid, and hydrochloric acid.

24. A liquid crystal display device according to claim 19, wherein the first transparent electrode having the uneven surface is formed by forming an amorphous transparent conductive film over a substrate, forming a crystalline portion in the amorphous transparent conductive film by sintering, polishing the transparent conductive film including the crystalline portion, and etching the transparent conductive film including the crystalline portion.

25. A liquid crystal display device according to claim 24, the polishing step is conducted by CMP.

26. A liquid crystal display device according to claim 19, wherein a rate of an area occupied by the reflection electrode is 50 through 90% of an area occupied by the first transparent electrode.

27. A liquid crystal display device according to claim 19, wherein the liquid crystal display device is incorporated into an electronic device selected from the group constituting of a digital still camera, a notebook type personal computer, a mobile computer, a portable image reproducing device having a record medium, a video camera, and a portable telephone.