Method for forming alignment layer and method for manufacturing liquid crystal display device using the same

1. A method for forming an alignment layer for a liquid crystal display device, the method comprising:

preparing a substrate;

coating an alignment material on the substrate;

rubbing the substrate having the alignment material coated thereon; and

performing a photo-alignment by irradiating ultraviolet (UV) rays onto the substrate having the alignment material coated thereon,

wherein the UV rays are irradiated over at least one area of the substrate having the alignment material coated thereon,

wherein the at least one area is either an entire surface of the substrate having the alignment material coated thereon, or a step region on the substrate having the alignment material coated thereon in which case other regions are being shielded with at least one mask, and

wherein the direction of rubbing and the polarized direction of the UV rays are vertical to each other when the photo-alignment is realized by a photo-decomposition reaction, or the direction of rubbing and the polarized direction of the UV rays are parallel to each other when the photo-alignment is realized by a photo-isomerization reaction or a photo-dimerization reaction.

2. The method according to claim 1 , wherein the step of rubbing is performed before the step of irradiating the UV rays.

3. The method according to claim 1 , wherein the step of irradiating the UV rays is performed before the step of rubbing.

4. The method according to claim 1 , wherein the step of rubbing and the step of irradiating the UV rays are performed at the same time.

5. The method according to claim 1 , wherein the step of preparing the substrate comprises:

forming a gate line and a data line crossing each other on a transparent substrate to define a pixel region thereon;

forming a thin film transistor on a crossing region of the gate line and the data line, the thin film transistor including a gate electrode, a source electrode and a drain electrode; and

forming a pixel electrode connected to the drain electrode of the thin film transistor.

6. The method according to claim 5 , wherein the step of irradiating the UV rays is performed while shielding regions other than a gate line region, a data line region and a thin film transistor region with at least one mask.

7. The method according to claim 1 , wherein the step of preparing the substrate comprises:

forming a gate line and a data line crossing each other on a transparent substrate to define a pixel region thereon;

forming a thin film transistor on a crossing region of the gate line and the data line, the thin film transistor including a gate electrode, a source electrode and a drain electrode;

forming a pixel electrode connected to the drain electrode of the thin film transistor; and

forming a common electrode parallel to the pixel electrode.

8. The method according to claim 7 , wherein the step of irradiating the UV rays is performed while shielding regions other than a gate line region, a data line region, a thin film transistor region, a pixel electrode region, and a common electrode region with at least one mask.

9. The method according to claim 1 , wherein the step of preparing the substrate comprises:

forming a light shielding layer on a transparent substrate;

forming color filter layers on the light shielding layer;

forming a common electrode on the color filter layers; and

forming column spacers on the common electrode.

10. The method according to claim 9 , wherein the step of irradiating the UV rays is performed while shielding regions other than column spacer regions with at least one mask.

11. The method according to claim 1 , wherein the step of preparing the substrate comprises:

forming a light shielding layer on a transparent substrate;

forming color filter layers on the light shielding layer;

forming an overcoat layer on the color filter layers; and

forming column spacers on the overcoat layer.

12. The method according to claim 11 , wherein the step of irradiating the UV rays is performed while shielding regions other than column spacer regions with at least one mask.

13. The method according to claim 1 , wherein in the irradiating step, the UV rays are partially or linearly polarized.

14. The method according to claim 1 , wherein in the irradiating step, the UV rays have an irradiation wavelength in the range of 200 nm to 400 nm.

15. The method according to claim 14 , wherein the UV rays have an irradiation wavelength of 200 nm or more and less than 300 nm, and an irradiation energy in the range of 0.05 J to 2 J.

16. The method according to claim 14 , wherein the UV rays have an irradiation wavelength of 300 nm or more and 400 nm or less, and an irradiation energy in the range of 0.2 J to 9 J.

17. The method according to claim 1 , wherein in the irradiating step, the UV rays are polarized and are irradiated vertically or obliquely to the substrate.

18. The method according to claim 1 , wherein the alignment material is a polymeric material selected from the group consisting of polyimide, polyamic acid, polyvinylcinnamate, polyazobenzene, polyethyleneimine, polyvinyl alcohol, polyamide, polyethylene, polystyrene, polyphenylenephthalamide, polyester, polyurethane, and polymethyl methacrylate.

19. The method according to claim 1 , wherein an alignment direction of the alignment material produced by the rubbing step is identical to an alignment direction of the alignment material produced by the irradiating step.

20. A method for manufacturing a liquid crystal display device, the method comprising:

preparing first and second substrates;

coating an alignment material on at least one of the substrates;

rubbing the substrate having the alignment material coated thereon;

performing a photo-alignment by irradiating ultraviolet rays onto the substrate having the alignment material coated thereon; and

combining both substrates,

wherein the ultraviolet rays are irradiated over at least one area of the substrate having the alignment material coated thereon,

wherein the at least one area is either an entire surface of the substrate having the alignment material coated thereon, or a step region on the substrate having the alignment material coated thereon in which case other regions are shielded with at least one mask, and

wherein the direction of rubbing and the polarized direction of the UV rays are vertical to each other when the photo-alignment is realized by a photo-decomposition reaction, or the direction of rubbing and the polarized direction of the UV rays are parallel to each other when the photo-alignment is realized by a photo-isomerization reaction or a photo-dimerization reaction.

21. The method according to claim 20 , further comprising:

dropping liquid crystals onto one of the substrates before the combining step.

22. The method according to claim 20 , wherein an alignment direction of the alignment material produced by the rubbing step is identical to an alignment direction of the alignment material produced by the irradiating step.

23. The method according to claim 20 , wherein the rubbing step is performed before or after the irradiating step.

24. The method according to claim 20 , wherein the rubbing step is performed at the same time as the irradiating step.