Liquid crystal display device and method of manufacturing the same

• US 7,656,491 B2
• Filed: 08/29/2006
• Issued: 02/02/2010
• Est. Priority Date: 03/16/2000
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu, Yamazaki, Shunpei
• Primary Examiner(s): RUDE, TIMOTHY L
• Application Number:
  US11/511,440
• Publication Number:
  US 20070058121A1
• Time in Patent Office: 1,253 Days
• Field of Search: 349/141
• US Class Current: 349/141
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• 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 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/13452 Conductors connecting driver circuitry and terminals of panels
• CPC Class Codes: G02F 1/13458 Terminal pads
• CPC Class Codes: G02F 1/136204 Arrangements to prevent high voltage or static electricity failures
• CPC Class Codes: G02F 1/136231 for reducing the number of lithographic steps
• CPC Class Codes: G02F 1/136277 formed on a semiconductor substrate, e.g. of silicon
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/13629 Multilayer wirings
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 1/1396 the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell G02F1/141 takes precedence
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• 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 27/1222 with a particular composition, shape or crystalline structure of the active layer
• 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 29/78669 with inverted-type structure, e.g. with bottom gate

Abstract

In a liquid crystal display device of an IPS system, to realize reduction of manufacturing cost and improvement of yield by decreasing the number of steps for manufacturing a TFT. A channel etch type bottom gate TFT structure, where patterning of a source region and a drain region and patterning of a source wiring and a pixel electrode are carried out by the same photomask.

Claims

1. A method of manufacturing a liquid crystal display device comprising:

forming a gate wiring and a common electrode over an insulating surface by using a first mask;

forming an insulating film over the gate wiring and the common electrode;

forming a first amorphous semiconductor film over the insulating film;

forming a second amorphous semiconductor film containing an impurity element which imparts n-type conductivity, over the first amorphous semiconductor film;

forming a conductive film over the second amorphous semiconductor film;

patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film together so that outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by using a second mask;

removing a portion of the first amorphous semiconductor film, a portion of the second amorphous semiconductor film and a portion of the conductive film to form a source region and a drain region after patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film; and

forming a pixel electrode electrically connected to the conductive film,

wherein the portion of the second amorphous semiconductor film is between the source region and the drain region, and

wherein the pixel electrode and the common electrode are disposed so that liquid crystal molecules are controlled by an electric field produced between the pixel electrode and the common electrode.

2. The method of manufacturing the liquid crystal display device according to claim 1, wherein the insulating film, the first amorphous semiconductor film, and the second amorphous semiconductor film are formed in succession without exposure to an atmosphere.

3. The method of manufacturing the liquid crystal display device according to claim 1, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by sputtering.

4. The method of manufacturing the liquid crystal display device according to claim 1, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by plasma CVD.

5. The method of manufacturing the liquid crystal display device according to claim 1, wherein the gate wiring is formed from an element selected from the group consisting of Al, Cu, Ti, Mo, W, Ta, Nd, and Cr, and an alloy of the elements.

6. The method of manufacturing the liquid crystal display device according to claim 1, wherein inside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by removing the portion of the first amorphous semiconductor film, the portion of the second amorphous semiconductor film and the portion of the conductive film.

7. The method of manufacturing the liquid crystal display device according to claim 1, further comprising forming a transparent conductive film to cover the outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film.

8. A method of manufacturing a liquid crystal display device comprising:

forming a gate wiring and a common electrode over an insulating surface by using a first mask;

forming an insulating film over the gate wiring and the common electrode;

forming a first amorphous semiconductor film over the insulating film;

forming a second amorphous semiconductor film containing an impurity element which imparts n-type conductivity, over the first amorphous semiconductor film;

forming a conductive film over the second amorphous semiconductor film;

patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film together so that outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by using a second mask; and

removing a portion of the first amorphous semiconductor film, a portion of the second amorphous semiconductor film and a portion of the conductive film to form a source region, a drain region, a source wiring and a pixel electrode after patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film,

wherein the portion of the second amorphous semiconductor film is between the source region and the drain region,

wherein the portion of the conductive film is between the source wiring and the pixel electrode, and

wherein the pixel electrode and the common electrode are disposed so that liquid crystal molecules are controlled by an electric field produced between the pixel electrode and the common electrode.

9. The method of manufacturing the liquid crystal display device according to claim 8, wherein the insulating film, the first amorphous semiconductor film, and the second amorphous semiconductor film are formed in succession without exposure to an atmosphere.

10. The method of manufacturing the liquid crystal display device according to claim 8, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by sputtering.

11. The method of manufacturing the liquid crystal display device according to claim 8, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by plasma CVD.

12. The method of manufacturing the liquid crystal display device according to claim 8, wherein the gate wiring is formed from an element selected from the group consisting of Al, Cu, Ti, Mo, W, Ta, Nd, and Cr, and an alloy of the elements.

13. The method of manufacturing the liquid crystal display device according to claim 8, wherein inside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by removing the portion of the first amorphous semiconductor film, the portion of the second amorphous semiconductor film and the portion of the conductive film.

14. The method of manufacturing the liquid crystal display device according to claim 8, further comprising forming a transparent conductive film to cover the outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film.

15. A method of manufacturing a liquid crystal display device comprising:

forming a gate wiring and a common electrode over an insulating surface by using a first mask;

forming an insulating film over the gate wiring and the common electrode;

forming a first amorphous semiconductor film over the insulating film;

forming a second amorphous semiconductor film containing an impurity element which imparts n-type conductivity, over the first amorphous semiconductor film;

forming a conductive film over the second amorphous semiconductor film;

patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film together so that outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by using a second mask;

removing a portion of the first amorphous semiconductor film, a portion of the second amorphous semiconductor film and a portion of the conductive film to form a source region and a drain region by using a third mask after patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film; and

forming a pixel electrode electrically connected to the conductive film,

wherein the portion of the second amorphous semiconductor film is between the source region and the drain region, and

wherein the pixel electrode and the common electrode are disposed so that liquid crystal molecules are controlled by an electric field produced between the pixel electrode and the common electrode.

16. The method of manufacturing the liquid crystal display device according to claim 15, wherein the insulating film, the first amorphous semiconductor film, and the second amorphous semiconductor film are formed in succession without exposure to an atmosphere.

17. The method of manufacturing the liquid crystal display device according to claim 15, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by sputtering.

18. The method of manufacturing the liquid crystal display device according to claim 15, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by plasma CVD.

19. The method of manufacturing the liquid crystal display device according to claim 15, wherein the gate wiring is formed from an element selected from the group consisting of Al, Cu, Ti, Mo, W, Ta, Nd, and Cr, and an alloy of the elements.

20. The method of manufacturing the liquid crystal display device according to claim 15, wherein inside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by removing the portion of the first amorphous semiconductor film, the portion of the second amorphous semiconductor film and the portion of the conductive film.

21. The method of manufacturing the liquid crystal display device according to claim 15, further comprising forming a transparent conductive film to cover the outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film.

22. A method of manufacturing a liquid crystal display device comprising:

forming a gate wiring and a common electrode over an insulating surface by using a first mask;

forming an insulating film over the gate wiring and the common electrode;

forming a first amorphous semiconductor film over the insulating film;

forming a second amorphous semiconductor film containing an impurity element which imparts n-type conductivity, over the first amorphous semiconductor film;

forming a conductive film over the second amorphous semiconductor film;

patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film together so that outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by using a second mask; and

removing a portion of the first amorphous semiconductor film, a portion of the second amorphous semiconductor film and a portion of the conductive film to form a source region, a drain region, a source wiring and a pixel electrode by using a third mask after patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film,

wherein the portion of the second amorphous semiconductor film is between the source region and the drain region,

wherein the portion of the conductive film is between the source wiring and the pixel electrode, and

wherein the pixel electrode and the common electrode are disposed so that liquid crystal molecules are controlled by an electric field produced between the pixel electrode and the common electrode.

23. The method of manufacturing the liquid crystal display device according to claim 22, wherein the insulating film, the first amorphous semiconductor film, and the second amorphous semiconductor film are formed in succession without exposure to an atmosphere.

24. The method of manufacturing the liquid crystal display device according to claim 22, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by sputtering.

25. The method of manufacturing the liquid crystal display device according to claim 22, wherein the insulating film, the first amorphous semiconductor film, or the second amorphous semiconductor film is formed by plasma CVD.

26. The method of manufacturing the liquid crystal display device according to claim 22, wherein the gate wiring is formed from an element selected from the group consisting of Al, Cu, Ti, Mo, W, Ta, Nd, and Cr, and an alloy of the elements.

27. The method of manufacturing the liquid crystal display device according to claim 22, wherein inside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film are substantially coincided by removing the portion of the first amorphous semiconductor film, the portion of the second amorphous semiconductor film and the portion of the conductive film.

28. The method of manufacturing the liquid crystal display device according to claim 22, further comprising forming a transparent conductive film to cover the outside end faces of the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film.