Liquid crystal display device and fabricating method thereof

• US 20060139502A1
• Filed: 11/10/2005
• Published: 06/29/2006
• Est. Priority Date: 12/24/2004
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Ahn, Byung Chul, Park, Byung Ho, Park, Jong Hyun
• Granted Patent: US 7,489,379 B2
• Time in Patent Office: Days
• US Class Current: 349/38
• CPC Class Codes: G02F 1/1339 Gaskets; Spacers; Sealing of cells
• CPC Class Codes: G02F 1/136231 for reducing the number of lithographic steps
• 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 2201/123 pixel
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• 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 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask
• CPC Class Codes: H01L 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after the gate

Abstract

A liquid crystal display device, including: a gate line on a substrate; a data line crossing the gate line with a gate insulating film in between to define a pixel area; a thin film transistor having a gate electrode connected to the gate line, a source electrode connected to the data line, a drain electrode facing the source electrode, and a semiconductor pattern providing a channel between the source electrode and the drain electrode; and a pixel electrode in the pixel area connected to the drain electrode, wherein the data line, the source electrode, and the drain electrode are formed of a first conductive layer group of double conductive layers, the pixel electrode is formed of the lowermost layer of the extended drain electrode, and the data line, the source electrode, the drain electrode, and the pixel electrode are in an area that is to be sealed by a sealant.

Claims

1. A liquid crystal display device, comprising:

a gate line on a substrate;

a data line crossing the gate line with a gate insulating film in between to define a pixel area;

a thin film transistor having a gate electrode connected to the gate line, a source electrode connected to the data line, a drain electrode facing the source electrode, and a semiconductor pattern providing a channel between the source electrode and the drain electrode; and

a pixel electrode in the pixel area connected to the drain electrode,

wherein the data line, the source electrode, and the drain electrode are formed of a first conductive layer group of double conductive layers, the pixel electrode is formed of the lowermost layer of the extended drain electrode, and the data line, the source electrode, the drain electrode, and the pixel electrode are in an area that is to be sealed by a sealant.

2. The device according to claim 1, further comprising:

a storage capacitor formed by overlapping the pixel electrode with the gate line with the gate insulating film in between.

3. The device according to claim 1, wherein the first conductive layer group has a transparent conductive layer as a lowermost layer.

4. The device according to claim 1, further comprising:

a gate pad connected to the gate line; and

a data pad connected to the data line,

wherein each of the gate pad and the data pad includes;

a pad lower electrode formed together with the gate line on the substrate;

a contact hole penetrating the gate insulating film to expose the pad lower electrode; and

a pad upper electrode formed as a lowermost layer of the first conductive layer group to connect to the pad lower electrode through the contact hole.

5. The device according to claim 4, further comprising:

a data link extending from a lower electrode of the data pad to partially overlap the data line; and

a second contact hole penetrating the gate insulating film to connect the data line to the data link.

6. The device according to claim 5, wherein the second contact hole is in an area that is sealed by the sealant.

7. The device according to claim 5, further comprising:

an alignment film on the data line, the source electrode, the drain electrode, and the pixel electrode.

8. The device according to claim 7, wherein the second contact hole is located under the alignment film.

9. The device according to claim 1, wherein the semiconductor pattern is formed only in an area where the thin film transistor is to be formed.

10. The device according to claim 1, wherein the first conductive layer group has a step shape.

11. A method of fabricating a liquid crystal display device, comprising:

a first mask process of forming a first mask pattern group having a gate line and a gate electrode connected to the gate line on a substrate;

a second mask process of forming a gate insulating film to cover the first mask pattern group and a semiconductor pattern thereon; and

a third mask process of forming a third mask pattern group having a data line, a source electrode connected to the data line, a drain electrode facing the source electrode, and a pixel electrode on the gate insulating film where the semiconductor pattern is formed, so that the third mask pattern group is located in an area sealed by a sealant, wherein the data line, the source electrode, and the drain electrode have double conductive layers, and the pixel electrode has a single layer structure where the lowermost layer of the drain electrode is extended.

12. The method according to claim 11, further comprising:

forming an alignment film on the third mask pattern group.

13. The method according to claim 11, wherein

the first mask process further includes forming a pad lower electrode connected to at least one of the gate line and the data line;

the second mask process further includes forming a contact hole that penetrates the gate insulating film to expose the pad lower electrode; and

the third mask process further includes forming a pad upper electrode from the lowermost layer of the second conductive layer group to be connected to the pad lower electrode through the contact hole.

14. The method according to claim 13, wherein:

the first mask process includes forming a data link extending from the pad lower electrode to overlap the data line, and

the second mask process includes forming a second contact hole where the data link is connected to the data line.

15. The method according to claim 14, wherein the second mask process includes:

forming a gate insulating film, an amorphous silicon layer, and an amorphous silicon layer doped with impurities on the first mask pattern group;

forming a photo-resist pattern with different thicknesses by a photolithography process using at least one of a halftone mask and a diffractive exposure mask; and

forming the contact holes and the semiconductor pattern by an etching process using the photo-resist pattern.

16. The method according to claim 14, wherein the third mask process includes:

forming the first conductive layer group on the gate insulating film where the semiconductor pattern is formed;

forming a photo-resist pattern with different thicknesses using at least one of a halftone mask and a diffractive exposure mask;

forming a third mask pattern group having the pad upper electrode by patterning the first conductive layer group by the etching process using the photo-resist pattern;

removing the amorphous silicon layer doped with the impurities exposed through the source electrode and the drain electrode; and

etching the pad upper electrode by the etching process using the photo-resist pattern so as to leave only the lowermost layer thereof.

17. The method according to claim 16, wherein the first conductive layer group includes a transparent conductive layer as the lowermost layer.

18. The method according to claim 17, further comprising:

etching both side areas of an upper layer which are exposed by the photo-resist pattern so that an edge of the upper layer is located inside an edge of the lowermost layer, when the lowermost layer of the first conductive group is over-etched versus the upper layer when patterning the first conductive layer group.

19. The method according to claim 12, further comprising:

forming a storage capacitor by overlapping the pixel electrode with the gate line with the gate insulating film in between.

20. The method according to claim 15, wherein the second contact hole is formed in an area which is sealed by the sealant.

21. The method according to claim 14, wherein the second contact hole is under the alignment film.

22. The method according to claim 11, wherein the first conductive layer group has a step shape.