ARRAY SUBSTRATE FOR LIQUID CRYSTAL DISPLAY DEVICE AND METHOD OF FABRICATING THE SAME

• US 20110006290A1
• Filed: 07/06/2010
• Published: 01/13/2011
• Est. Priority Date: 07/07/2009
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: NOH, Young-Hoon, Kang, Ho-Cheol
• Granted Patent: US 9,064,832 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 59/1213 the pixel elements being TFTs
• CPC Class Codes: H10K 59/125 including organic TFTs [OTFT]

Abstract

An array substrate for a display device, including a substrate having a pixel region and a switching region, a source electrode and a drain electrode on the switching region of the substrate, ends of the source and drain electrodes having tapered edges, a pixel electrode in the pixel region of the substrate, the pixel electrode being connected to the drain electrode, an organic semiconductor layer on the source and drain electrodes, the organic semiconductor layer completely contacting tapered edges and a top surface of each of the source and drain electrodes, a first insulating layer on the organic semiconductor layer, and a gate electrode on the first insulating layer.

Claims

1. An array substrate for a display device, comprising:

a substrate having a pixel region and a switching region;

a source electrode and a drain electrode on the switching region of the substrate, ends of the source and drain electrodes having tapered edges;

a pixel electrode in the pixel region of the substrate, the pixel electrode being connected to the drain electrode;

an organic semiconductor layer on the source and drain electrodes, the organic semiconductor layer completely contacting tapered edges and a top surface of each of the source and drain electrodes;

a first insulating layer on the organic semiconductor layer; and

a gate electrode on the first insulating layer.

2. The array substrate for a display device according to claim 1 wherein the tapered edges of the source and drain electrodes have an angle between 10 and 70 degrees with respect to a surface of the substrate.

3. The array substrate for a display device according to claim 1 wherein the organic semiconductor layer is formed in a liquid phase using one of an inkjet apparatus, a nozzle coating apparatus, a bar coating apparatus, a slit coating apparatus, and a spin coating apparatus.

4. The array substrate for a display device according to claim 1, wherein the organic semiconductor layer, the first insulating layer, and the gate electrode have substantially the same shape and area in a plane view.

5. The array substrate for a display device according to claim 4, further comprising a second insulating layer disposed on the gate electrode and a data line, the second insulating layer having a gate contact hole that exposes the gate electrode and an opening that exposes the pixel electrode, the gate line being disposed on the second insulating layer and connected to the gate electrode through the gate contact hole.

6. The array substrate for a display device according to claim 4, further comprising a buffer layer, the buffer layer being disposed on the substrate.

7. The array substrate for a display device according to claim 1 wherein a source-drain current increases substantially logarithmically with a source-drain voltage.

8. A method of fabricating an array substrate for a display device, comprising the steps of:

forming a substrate having a pixel region and a switching region;

forming a source electrode and a drain electrode on the switching region of the substrate, ends of the source and drain electrodes having tapered edges;

forming a pixel electrode in the pixel region of the substrate, the pixel electrode being connected to the drain electrode;

forming an organic semiconductor layer on the source and drain electrodes, the organic semiconductor layer completely contacting tapered edges and a top surface of each of the source and drain electrodes;

forming a first insulating layer on the organic semiconductor layer; and

forming a gate electrode on the first insulating layer.

9. The method of fabricating an array substrate for a display device according to claim 8, wherein the tapered edges of the source and drain electrodes have an angle between 10 and 70 degrees with respect to a surface of the substrate.

10. The method of fabricating an array substrate for a display device according to claim 8, wherein the organic semiconductor layer is formed in a liquid phase using one of an inkjet apparatus, a nozzle coating apparatus, a bar coating apparatus, a slit coating apparatus, and a spin coating apparatus.

11. The method of fabricating an array substrate for a display device according to claim 8, wherein the organic semiconductor layer, the first insulating layer, and the gate electrode have substantially the same shape and area in a plane view.

12. The method of fabricating an array substrate for a display device according to claim 8, further comprising the steps of:

forming a second insulating layer disposed on the gate electrode and a data line, and

forming a gate contact hole that exposes the gate electrode and an opening that exposes the pixel electrode in the second insulating layer,

wherein the gate line is disposed on the second insulating layer and is connected to the gate electrode through the gate contact hole.

13. The method of fabricating an array substrate for a display device according to claim 8, further comprising the step of forming a buffer layer, the buffer layer being disposed on the substrate.

14. The method of fabricating an array substrate for a display device according to claim 8, wherein a source-drain current increases substantially logarithmically with a source-drain voltage.

15. The method of fabricating an array substrate for a display device according to claim 8, wherein the steps of forming the data line, source electrode, and drain electrode further include the steps of:

forming a metal layer on the substrate;

forming a photoresist pattern on the metal layer that corresponds to a data line, source electrode, and drain electrode;

etching the metal layer using the photoresist pattern as an etching mask with an etchant having a temperature of about 33 to 50°

C. to form the data line, source electrode, and drain electrode; and

removing the photoresist pattern.

16. The method of fabricating an array substrate for a display device according to claim 15, wherein the step of etching includes isotropically dry-etching the metal layer using the photoresist pattern as an etching mask by sputter etching or chemical etching to form the data line, source electrode, and drain electrode.

17. A method of fabricating an array substrate for a liquid crystal display device, comprising:

forming a substrate having a pixel region and a switching region;

forming a data line on the substrate;

forming a source electrode and a drain electrode on the switching region of the substrate, the source electrode extending from the data line and being separated from the drain electrode, ends of the source and drain electrodes having an angle smaller than 90 degrees with respect to a surface of the substrate;

forming a pixel electrode in the pixel region of the substrate, the pixel electrode being connected to the drain electrode;

forming an organic semiconductor layer on the source and drain electrodes, the organic semiconductor layer contacting an inside end of each of the source and drain electrodes;

forming a gate insulating layer on the organic semiconductor layer;

forming a gate electrode on the gate insulating layer;

forming a gate line connected to the gate electrode and crossing the data line to define the pixel region; and

forming a first passivation layer on the gate electrode and the data line, a gate contact hole that exposes the gate electrode and an opening that exposes the pixel electrode being formed in the first passivation layer, the gate line being disposed on the second insulating layer and connected to the gate electrode through the gate contact hole.

18. The method of fabricating an array substrate for a liquid crystal display device according to claim 17, wherein the steps of forming the data line, source electrode, and drain electrode further include the steps of:

forming a metal layer on the substrate by depositing gold;

forming a photoresist pattern on the metal layer that corresponds to the data line, source electrode, and drain electrode;

etching the metal layer using the photoresist pattern as an etching mask with an etchant having a temperature of about 33 to 50°

C. to form the data line, source electrode, and drain electrode; and

removing the photoresist pattern.

19. The method of fabricating an array substrate for a liquid crystal display device according to claim 17, wherein the steps of forming the data line, source electrode and drain electrode further include the steps of:

forming a metal layer on the substrate by depositing molybdenum or molybdenum-titanium alloy;

forming a photoresist pattern on the metal layer that corresponds to the data line, source electrode, and drain electrode;

isotropically dry-etching the metal layer using the photoresist pattern as an etching mask by sputter etching or chemical etching to form the data line, source electrode, and drain electrode; and

removing the photoresist pattern.

20. The method of fabricating an array substrate for a liquid crystal display device according to claim 17 wherein the steps of forming the organic semiconductor layer, gate insulating layer, and gate electrode include:

sequentially forming an organic semiconductor material layer on the source and drain electrode, an organic insulating material layer on the organic semiconductor material layer, and a metal layer on the organic insulating material layer;

forming a photoresist pattern on the metal layer;

dry-etching the metal layer, the organic insulating material layer, and the organic semiconductor material layer using the photoresist pattern as an etching mask to form the organic semiconductor layer, gate insulating layer, and gate electrode; and

removing the photoresist pattern.

21. The method of fabricating an array substrate for a liquid crystal display device according to claim 17, further comprising the step of forming a buffer layer on the substrate by depositing an inorganic insulating material prior to the steps of forming the data line, source electrode, and the drain electrode.

22. The method of fabricating an array substrate for a liquid crystal display device according to claim 17 wherein the angle has a range within about 10 to 70 degrees.

23. A method of fabricating an array substrate for a liquid crystal display device, comprising the steps of:

forming a gate line and a gate electrode on a substrate having a pixel region and a switching region, the gate electrode extending from the gate line and positioned in the switching region;

forming a gate insulating layer on the gate line and the gate electrode by depositing an organic insulating material;

forming a data line, a source electrode and a drain electrode on the gate insulating layer, the source electrode extending from the data line and spaced apart from the drain electrode, ends of the source and drain electrodes having an angle smaller than 90 degrees with respect to a surface of the substrate, the source and drain electrodes positioned in the switching region;

forming a pixel electrode on the gate insulating layer and in the pixel region, the pixel electrode connected to the drain electrode;

forming an organic semiconductor layer on the source and drain electrodes and a first passivation layer on the organic semiconductor layer; and

forming a second passivation layer on the first insulating layer and including an opening, wherein the pixel electrode is exposed through the opening.

24. The method of fabricating an array substrate for a liquid crystal display device according to claim 23, wherein the step of forming the data line, the source electrode and the drain electrode includes:

forming a metal layer on the gate insulating layer by depositing gold;

forming a photoresist pattern on the metal layer and corresponding to the data line, the source electrode and the drain electrode;

etching the metal layer using the photoresist pattern as an etching mask with an etchant having a temperature of about 33 to 50°

C. to form the data line, the source electrode and the drain electrode; and

removing the photoresist pattern.

25. The method of fabricating an array substrate for a liquid crystal display device according to claim 23 wherein the step of forming the data line, source electrode, and drain electrode includes:

forming a metal layer on the gate insulating layer by depositing molybdenum or molybdenum-titanium alloy;

forming a photoresist pattern on the metal layer and corresponding to the data line, the source electrode and the drain electrode;

isotropically etching the metal layer using the photoresist pattern as an etching mask with a sputter etching or a chemical etching to form the data line, the source electrode and the drain electrode; and

removing the photoresist pattern.

26. The method of fabricating an array substrate for a liquid crystal display device according to claim 23 wherein the gate electrode covers a space between the source and drain electrodes.

27. The method of fabricating an array substrate for a liquid crystal display device according to claim 23 wherein the steps of forming the organic semiconductor layer and the first passivation layer include:

sequentially forming an organic semiconductor material layer on the source and drain electrode and an organic insulating material layer on the organic semiconductor material layer;

forming a photoresist pattern on the organic insulating material layer;

dry-etching the organic insulating material layer and the organic semiconductor material layer using the photoresist pattern as an etching mask to form the organic semiconductor layer and the first passivation layer; and

removing the photoresist pattern.

28. The method of fabricating an array substrate for a liquid crystal display device according to claim 23 wherein the angle has a range within about 10 to 70 degrees.