Electrowetting display device and manufacturing method thereof

1. An electrowetting display device comprising:

a lower substrate;

a pixel electrode disposed on the lower substrate;

a lower water-repellent layer comprising a first material disposed on the pixel electrode;

partitions disposed on the lower water-repellent layer, wherein the partitions have a reverse taper cross-section so that a thickness of the partitions decreases in a direction from a top of the partitions toward the lower water-repellent layer;

an upper water-repellent layer comprising a second material different from the first material of the lower water-repellent layer, the upper water-repellent layer disposed (i) on the lower water-repellent layer and (ii) between the partitions; and

an oil layer disposed on the upper water-repellent layer between the partitions.

2. The electrowetting display device of claim 1 , wherein the oil layer includes black oil.

3. The electrowetting display device of claim 1 , wherein the partitions are disposed on the lower water-repellent layer in the form of a matrix pattern with an opening defined between the partitions, and wherein an area of a lower surface of the partitions is smaller than an area of the upper surface of the partitions.

4. The electrowetting display device of claim 3 , wherein the partitions are formed of an organic layer comprising a black dye.

5. The electrowetting display device of claim 1 , wherein the lower water-repellent layer has an increasing portion protruded upward along the partitions.

6. The electrowetting display device of claim 5 , wherein the partitions having the reverse taper cross-section covers the increasing portion of the lower water-repellent layer or an increasing portion of the upper water-repellent layer protruded upward along the partitions.

7. The electrowetting display device of claim 1 , further comprising:

impurities comprising residue of material used to form the partitions, the impurities disposed between the upper water-repellent layer and the lower water-repellent layer.

8. The electrowetting display device of claim 1 , wherein

at least one of the lower water-repellent layer or the upper water-repellent layer has an increasing portion protruded upward along the side wall of the partitions.

9. The electrowetting display device of claim 8 , wherein the increasing portion includes a portion of the lower water-repellent layer protruded upward along the partitions.

10. The electrowetting display device of claim 8 , wherein the increasing portion includes a portion of the lower water-repellent layer protruded upward along the partitions and a portion of the upper water-repellent layer protruded upward along the partitions.

11. The electrowetting display device of claim 1 , wherein

the oil layer does not contact with the partitions.

12. The electrowetting display device of claim 1 , further comprising:

an upper substrate; and

a black matrix disposed under the upper substrate at a position which corresponds to the partitions and wherein the black matrix is wider than an upper surface of the partitions.

13. The electrowetting display device of claim 12 , further comprising:

a flatness layer disposed under the black matrix and the upper substrate; and

a common electrode disposed under the flatness layer.

14. A method manufacturing an electrowetting display device comprising:

forming a pixel electrode on a substrate;

forming a lower water-repellent layer on the pixel electrode;

forming partitions having a reverse taper cross-section on the lower water-repellent layer; and

forming an upper water-repellent layer on the lower water-repellent layer between the partitions,

wherein an angle of the reverse taper cross-section of the partitions is based, at least in part, on a degree by which the upper water-repellent layer and the lower water-repellent layer creep up the partitions.

15. The method of claim 14 , wherein

the forming of the partitions comprise:

changing a hydrophobic characteristic of the lower water-repellent layer into a hydrophilic characteristic by performing a reactive ion etching (RIE) process on the lower water-repellent layer;

depositing an organic layer comprising a black dye and a photoresist on the lower water-repellent layer;

exposing and developing the photoresist through a mask to form a photoresist pattern; and

wet-etching the photoresist pattern and the organic layer to generate an under-cut to thereby form the partitions.

16. The method of claim 15 , further comprising:

hard-baking the etched partition pattern at a high temperature, and

wherein the hard baking process causes a portion of the lower water-repellent layer having fluidity at the high temperature to thereby form an increasing portion which creeps up the partitions by a capillary force.

17. The method of claim 15 , further comprising:

changing the hydrophilic characteristic of the lower water-repellent layer into a hydrophobic characteristic through reflow of the lower water-repellent layer after forming the partitions.

18. The method of claim 14 , wherein the upper water-repellent layer is formed by an Inkjet method only in an opening between the partitions.

19. The method of claim 18 , wherein the upper water-repellent layer forms an increasing portion while hydrophobic insulating material injected by the inkjet method creeps up the partitions by a capillary force.

20. The method of claim 14 , wherein at least one of the lower water-repellent layer or the upper water-repellent layer is formed with an increasing portion near the partitions, and

wherein the reverse taper cross-section of the partitions cover the increasing portion of at least one of the lower water-repellent layer or the upper water-repellent layer.

21. The method of claim 14 , further comprising:

after forming the upper water-repellent layer, forming a black oil layer on the lower water-repellent layer between the partitions.

22. The method of claim 21 , wherein

the black oil layer does not contact with the partitions.

23. The method of claim 14 , further comprising:

forming an upper substrate;

forming a black matrix under the upper substrate,

wherein the black matrix is disposed at a position corresponding to the partitions and is wider than an upper surface of the partitions.

24. An electrowetting display device comprising:

a lower substrate;

a pixel electrode formed on an upper surface of the lower substrate;

a lower water-repellent layer comprising a first material formed on the pixel electrode;

a plurality of partitions formed on the lower water-repellent layer, wherein the partitions have a reverse taper cross-section;

an upper water-repellent layer comprising a second material different from the first material of the lower water-repellent layer, the upper water-repellent layer formed on the lower water-repellent layer and inside an opening defined between the partitions, wherein a portion of at least one of the lower water-repellent layer or the upper water-repellent layer protrudes upward along the side wall of the partitions;

an oil layer formed on the upper water-repellent layer in the opening between the partitions;

an upper substrate facing the lower substrate;

a common electrode formed on a lower surface of the upper substrate; and

an aqueous solution layer disposed between the oil layer and the common electrode.

25. The electrowetting display device of claim 24 , wherein the oil layer includes black oil and wherein the lower water-repellent layer and the upper water-repellent layer are each formed of different amorphous fluoropolymers.