Liquid crystal display device and method of manufacturing the same

• US 9,298,056 B2
• Filed: 10/20/2014
• Issued: 03/29/2016
• 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:
  US14/518,129
• Publication Number:
  US 20150085235A1
• Time in Patent Office: 526 Days
• US Class Current: 1/1
• 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 first insulating film comprising silicon nitride over the gate 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 first wiring over and electrically connected to one of the pair of second amorphous semiconductor films;

a second wiring over and electrically connected to the other of the pair of second amorphous semiconductor films;

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

a transparent electrode in direct contact with a side surface of the second wiring;

a common electrode;

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

a liquid crystal over the alignment film,

wherein the common electrode and the transparent electrode overlap each other,

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

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

wherein a part of the first amorphous semiconductor film and a part of the pair of second amorphous semiconductor films overlap the gate wiring,

wherein the second insulating film is in contact with the part of the first amorphous semiconductor film and the part of the pair of second amorphous semiconductor films, and

wherein the first wiring overlaps the gate wiring and the common electrode.

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

3. The liquid crystal display device according to claim 1, wherein the gate wiring and the common electrode 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. The liquid crystal display device according to claim 1, wherein the transparent electrode and the common electrode are disposed so that an orientation of the liquid crystal is controlled by an electric field produced between the transparent electrode and the common electrode.

6. A liquid crystal display device comprising:

a gate wiring over an insulating surface;

a first insulating film comprising silicon nitride over the gate 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 first wiring over and electrically connected to one of the pair of second amorphous semiconductor films;

a second wiring over and electrically connected to the other of the pair of second amorphous semiconductor films;

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

a transparent electrode in direct contact with a side surface of the second wiring;

a common electrode;

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

a liquid crystal over the alignment film; and

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

wherein the common electrode and the transparent electrode overlap each other,

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

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

wherein a part of the first amorphous semiconductor film and a part of the pair of second amorphous semiconductor films overlap the gate wiring,

wherein the second insulating film is in contact with the part of the first amorphous semiconductor film and the part of the pair of second amorphous semiconductor films, and

wherein the first wiring overlaps the gate wiring and the common electrode.

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

8. The liquid crystal display device according to claim 6, wherein the gate wiring and the common electrode are formed by patterning a second conductive layer.

9. The liquid crystal display device according to claim 6, 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.

10. The liquid crystal display device according to claim 6, wherein the transparent electrode and the common electrode are disposed so that an orientation of the liquid crystal is controlled by an electric field produced between the transparent electrode and the common electrode.

11. A liquid crystal display device comprising:

a gate wiring over an insulating surface;

a first insulating film over the gate 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 first wiring over and electrically connected to one of the pair of second amorphous semiconductor films;

a second wiring over and electrically connected to the other of the pair of second amorphous semiconductor films;

a second insulating film over the first wiring and the second wiring;

a transparent electrode in direct contact with a side surface of the second wiring;

a common electrode;

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

a liquid crystal over the alignment film; and

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

wherein the common electrode and the transparent electrode overlap each other,

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

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

wherein a part of the first amorphous semiconductor film and a part of the pair of second amorphous semiconductor films overlap the gate wiring,

wherein the second insulating film is in contact with the part of the first amorphous semiconductor film and the part of the pair of second amorphous semiconductor films, and

wherein the first wiring overlaps the gate wiring and the common electrode.

12. The liquid crystal display device according to claim 11, wherein the common electrode is formed in a same layer as the gate wiring.

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

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

15. The liquid crystal display device according to claim 11, wherein the transparent electrode and the common electrode are disposed so that an orientation of the liquid crystal is controlled by an electric field produced between the transparent electrode and the common electrode.