Liquid crystal display device and fabricating method thereof

• US 20050263769A1
• Filed: 05/26/2005
• Published: 12/01/2005
• Est. Priority Date: 05/27/2004
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Chul Ahn, Byung
• Granted Patent: US 7,351,623 B2
• Time in Patent Office: Days
• US Class Current: 257/72
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136236 using a grey or half tone lithographic process
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/13629 Multilayer wirings
• 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 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask

Abstract

A thin film transistor substrate of a LCD device and a fabricating method thereof are disclosed for simplifying a fabricating process and enlarging a capacitance value of a storage capacitor without any reduction of aperture ratio. The LCD device includes: a double-layered gate line having a first transparent conductive layer and a second opaque conductive layer, the second opaque conductive layer have a step coverage; a gate insulation layer film on the gate line; a data line crossing the gate line to define a pixel region; a TFT connected to the gate line and the data line; a pixel electrode connected to the TFT via a contact hole of a protective film on the TFT; and a storage capacitor overlapping the pixel electrode and having a lower storage electrode formed of the first transparent conductive layer.

Claims

1. A liquid crystal display device, comprising:

a double-layered gate line having a first transparent conductive layer and a second opaque conductive layer, the second opaque conductive layer having a step coverage;

a gate insulation film on the gate line;

a data line crossing the gate line to define a pixel region;

a thin film transistor connected to the gate line and the data line;

a pixel electrode connected to the thin film transistor via a contact hole of a protective film on the thin film transistor; and

a storage capacitor overlapping the pixel electrode and having a lower storage electrode formed of the first transparent conductive layer.

2. The device of claim 1, wherein the lower storage electrode protrudes from the first transparent conductive layer of the gate line toward the pixel region.

3. The device of claim 1, further comprising a common line crossing the pixel electrode and the data line.

4. The device of claim 3, wherein the common line is formed of the first transparent conductive layer of the lower storage electrode.

5. The device of claim 3, wherein the common line is formed similar to the double-layer of the gate line.

6. The device of claim 5, wherein the lower storage electrode protrudes from a first conductive layer of the gate line toward the pixel region.

7. The device of claim 1, further comprising a redundancy line independently formed between the gate lines.

8. The device of claim 7, wherein the redundancy line overlaps the data line.

9. The device of claim 7, wherein the redundancy line is formed of one of the first transparent conductive layer and a double-layer of the gate line.

10. The device of claim 1, further comprising a light-shielding pattern protruded from the second conductive layer of the gate line and overlapping with both sides of the pixel electrode.

11. The device of claim 10, wherein the light-shielding pattern overlaps the lower storage electrode.

12. The device of claim 1, further comprising a gate pad including a lower gate pad electrode having a double-layer and an upper gate pad electrode connected to the lower gate pad electrode via a contact hole of the gate insulating film and the protective film, wherein the lower gate pad electrode is connected to the gate line.

13. The device of claim 1, further comprising a data pad including a lower data pad electrode connected to the data line, and an upper data pad electrode connected to the lower data pad electrode via a contact hole of the protective film.

14. The device of claim 1, wherein the gate line further includes a third conductive layer on the second conductive layer.

15. The device of claim 1, wherein a gate electrode of the thin film transistor is connected to the gate line, the gate electrode having a double-layer.

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

forming a gate pattern including a gate line, a gate electrode and a lower storage electrode on a substrate using a first mask, the gate line and the gate electrode being formed of a double-layer having a transparent conductive layer, and the lower storage electrode being formed of the transparent conductive layer;

forming a gate insulating film on the gate pattern;

forming a semiconductor pattern and a source/drain pattern having a data line and source and drain electrodes on the gate insulating film using a second mask, the data line defining a pixel region with the gate line;

forming a protective film on the source/drain pattern, and forming a contact hole exposing the drain electrode using a third mask; and

forming a pixel electrode connected to the drain electrode via the contact hole on the protective film and overlapping with the lower storage electrode using a fourth mask.

17. The method of claim 16, wherein forming the gate pattern includes:

forming a first conductive layer as the transparent conductive layer and a second conductive layer on the substrate;

forming first and second photo-resist patterns having a different thickness on the second conductive layer by photolithography using the first mask;

forming the gate line, the gate electrode and the lower storage electrode by patterning the first and second conductive layers by etching using the first and second photo-resist patterns;

removing the second conductive layer on the lower storage electrode by etching using the first photo-resist pattern; and

removing the first photo-resist pattern.

18. The method of claim 17, further comprising thinning the first photo-resist pattern and removing the second photo-resist pattern by ashing after forming the gate line, the gate electrode and the lower storage electrode.

19. The method of claim 16, wherein the lower storage electrode protrudes from the transparent conductive layer of the gate line toward the pixel region.

20. The method of claim 17, wherein forming the gate pattern further includes forming a common line crossing the pixel electrode and the data line, the common line being formed of a transparent conductive layer having the lower storage electrode.

21. The method of claim 16, wherein the forming the gate pattern includes forming a common line crossing the pixel electrode and the data line, the common line having being double layered,

wherein the lower storage electrode protrudes from a first conductive layer of the common line toward the pixel region.

22. The method of claim 16, wherein the forming the gate pattern includes a redundancy line independently overlapping the data line between the gate lines.

23. The method of claim 22, wherein the redundancy line is formed of one of a first conductive layer and double-layer structure.

24. The method of claim 16, wherein forming the gate pattern includes forming a light-shielding pattern protruded from a second conductive layer of the gate line to overlap both sides of the pixel electrode.

25. The method of claim 24, wherein the light-shielding pattern overlaps the lower storage electrode.

26. The method of claim 16, further comprising:

forming a lower gate pad electrode having a double-layer, the lower gate pad electrode being connected to the gate line;

forming a second contact hole passing through the gate insulating film and the protective film; and

forming an upper gate pad electrode connected to the lower gate pad electrode via the second contact hole.

27. The method of claim 26, further comprising:

forming a lower data pad electrode connected to the data line;

forming a third contact hole passing through the protective film; and

forming an upper data pad electrode connected to the lower data pad electrode via the third contact hole.

28. The method of claim 16, wherein forming the gate pattern further includes forming a third conductive layer along with a second conductive layer.

29. The method of claim 16, wherein first and second conductive layers of the double-layer have a constant step coverage.

30. The method of claim 16, wherein the first mask is a half tone mask.

31. The method of claim 16, wherein the second mask is a diffractive exposure mask.

32. The method of claim 16, wherein the semiconductor pattern overlaps the date line.