Liquid crystal display device and method of manufacturing the same

• US 8,610,861 B2
• Filed: 07/19/2012
• Issued: 12/17/2013
• Est. Priority Date: 03/16/2000
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Hirakata, Yoshiharu
• Primary Examiner(s): Rude, Timothy L
• Application Number:
  US13/553,031
• Publication Number:
  US 20120281177A1
• Time in Patent Office: 516 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 liquid crystal display device comprising:

a gate wiring over an insulating surface;

a common wiring over the insulating surface;

a first insulating film comprising silicon nitride over the gate wiring and the common wiring;

a first amorphous semiconductor film over the first insulating film;

a pair of second amorphous semiconductor films over the first amorphous semiconductor film;

a source wiring over one of the pair of second amorphous semiconductor films;

a second insulating film comprising silicon nitride over the source wiring;

a common electrode electrically connected to the common wiring;

a transparent electrode over the common electrode, and electrically connected to the other of the pair of second amorphous semiconductor films; and

an alignment film over the transparent electrode and the common electrode;

wherein the source wiring overlaps with the first amorphous semiconductor film and one of the pair of second amorphous semiconductor films,

wherein the first amorphous semiconductor film and one of the pair of second amorphous semiconductor films extend along the source wiring,

wherein the second insulating film is in contact with the first amorphous semiconductor film and the pair of second amorphous semiconductor films in a region overlapping with the gate wiring,

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

wherein the transparent electrode and the common wiring are overlapped with each other.

2. The liquid crystal display device according to claim 1, wherein the common electrode is formed in a same layer as the common wiring.

3. The liquid crystal display device according to claim 1, wherein the gate wiring and the common wiring are formed by patterning a conductive layer.

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

5. A liquid crystal display device comprising:

a gate wiring over an insulating surface;

a common wiring over the insulating surface;

a first insulating film comprising silicon nitride over the gate wiring and the common wiring;

a first amorphous semiconductor film over the first insulating film;

a pair of second amorphous semiconductor films over the first amorphous semiconductor film;

a source wiring over one of the pair of second amorphous semiconductor films;

a second insulating film comprising silicon nitride over the source wiring;

a common electrode electrically connected to the common wiring;

a transparent electrode over the common electrode, and electrically connected to the other of the pair of second amorphous semiconductor films;

an alignment film over the transparent electrode and the common electrode; and

a terminal portion comprising a conductive layer formed of a same layer as the transparent electrode,

wherein the source wiring overlaps with the first amorphous semiconductor film and one of the pair of second amorphous semiconductor films,

wherein the first amorphous semiconductor film and one of the pair of second amorphous semiconductor films extend along the source wiring,

wherein the second insulating film is in contact with the first amorphous semiconductor film and the pair of second amorphous semiconductor films in a region overlapping with the gate wiring,

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

wherein the transparent electrode and the common wiring are overlapped with each other.

6. The liquid crystal display device according to claim 5, wherein the common electrode is formed in a same layer as the common wiring.

7. The liquid crystal display device according to claim 5, wherein the gate wiring and the common wiring are formed by patterning a second conductive layer.

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

9. A liquid crystal display device comprising:

a gate wiring over an insulating surface;

a common wiring over the insulating surface;

a first insulating film over the gate wiring and the common wiring;

a first amorphous semiconductor film over the first insulating film;

a pair of second amorphous semiconductor films over the first amorphous semiconductor film;

a source wiring over one of the pair of second amorphous semiconductor films;

a second insulating film over the source wiring;

a common electrode electrically connected to the common wiring;

a transparent electrode over the common electrode, and electrically connected to the other of the pair of second amorphous semiconductor films;

an alignment film over the transparent electrode and the common electrode; and

a terminal portion comprising a conductive layer formed of a same layer as the transparent electrode,

wherein the source wiring overlaps with the first amorphous semiconductor film and one of the pair of second amorphous semiconductor films,

wherein the first amorphous semiconductor film and one of the pair of second amorphous semiconductor films extend along the source wiring,

wherein the second insulating film is in contact with the first amorphous semiconductor film and the pair of second amorphous semiconductor films in a region overlapping with the gate wiring,

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

wherein the transparent electrode and the common wiring are overlapped with each other.

10. The liquid crystal display device according to claim 9, wherein the common electrode is formed in a same layer as the common wiring.

11. The liquid crystal display device according to claim 9, wherein the gate wiring and the common wiring are formed by patterning a second conductive layer.

12. The liquid crystal display device according to claim 9, wherein the gate wiring comprises an element selected from the group consisting of Al, Cu, Ti, Mo, W, Ta, Nd, and Cr, and an alloy of the elements.