Substrate for liquid-crystal display device and fabrication method thereof
A substrate for a LCD device improves the flatness of the outermost substrate surface in the contact region for interconnecting an electrode of a switching element (e.g., a TFT) and a pixel electrode to each other in each pixel. Switching elements for respective pixels are formed on a transparent plate. Protrusions for the respective pixels are formed on the plate to protrude to a vicinity of an outermost surface of the substrate. Each protrusion raises an electrode of a corresponding switching element to the vicinity of the outermost surface in the corresponding pixel. A planarization layer forming the outermost surface is formed to cover the switching elements, the protrusions, and the electrodes of the elements in all the pixels. Pixel electrodes for the respective pixels are formed on the outermost surface. Each pixel electrode contacts the corresponding electrode of the element in the vicinity of the outermost surface.
1. A substrate for a LCD device comprising:
a transparent plate;
switching elements for respective pixels, formed on the plate;
protrusions for the respective pixels, formed on the plate in such a way as to protrude to a vicinity of an outermost surface of the substrate;
each of the protrusions raising an electrode of a corresponding one of the switching elements to the vicinity of the outermost surface in a corresponding one of the pixels;
a planarization layer formed in such a way as to cover the switching elements, the protrusions, and the electrodes of the elements in all the pixels, a surface of the planarization layer forming the outermost surface, the planarization layer having at least one contact hole formed over each corresponding protrusion, partially exposing the electrodes;
pixel electrodes for the respective pixels, formed on the outermost surface; and
each of the pixel electrodes being contacted with a corresponding one of the electrodes of the switching elements in the vicinity of the outermost surface.
2. The substrate according to claim 1 , wherein the switching elements are TFTs, and the electrodes of the switching elements are source electrodes or drain electrodes of the TFTs.
3. The substrate according to claim 1 , wherein each of the electrodes of the switching elements is extended along top and side faces of a corresponding one of the protrusions.
4. The substrate according to claim 1 , wherein each of the electrodes of the switching elements is extended along top and side faces of a corresponding one of the protrusions, and is contacted with a corresponding one of the pixel electrodes at a top of a corresponding one of the protrusions.
5. The substrate according to claim 1 , wherein the planarization layer includes a transparent organic interlayer dielectric sublayer.
6. The substrate according to claim 1 , further comprising a color filter; wherein a distance between a top of each of the protrusions and the outermost surface is shorter than a distance between a top of the color filter and the outermost surface.
7. The substrate according to claim 1 , further comprising a color filter; wherein a boundary of the filter on a side of each of the protrusions is superposed on a boundary of the planarization layer on a side of each of the protrusions.
8. A method of fabricating a substrate for a LCD device, comprising the steps of:
forming protrusions for respective pixels on a transparent plate in such a way as to protrude to a vicinity of an outermost surface of the substrate;
forming switching elements for the respective pixels in such a way that electrodes of the elements are raised by the corresponding protrusions to the vicinity of the outermost surface;
forming a planarization layer in such a way as to cover the switching elements, the protrusions, and the electrodes of the elements in all the pixels, a surface of the planarization layer forming the outermost surface;
forming at least one contact hole on the planarization layer and over each corresponding protrusion, partially exposing the electrodes; and
forming pixel electrodes for the respective pixels on the outermost surface;
wherein each of the pixel electrodes is contacted with a corresponding one of the electrodes of the switching elements in the vicinity of the outermost surface.
9. The method according to claim 8 , wherein the switching elements are TFTs, and the electrodes of the switching elements are source electrodes or drain electrodes of the TFTs.
10. The method according to claim 8 , wherein each of the electrodes of the switching elements is formed to extend along top and side faces of a corresponding one of the protrusions.
11. The method according to claim 8 , wherein each of the electrodes of the switching elements is formed to extend along top and side faces of a corresponding one of the protrusions and to contact a corresponding one of the pixel electrodes at a top of a corresponding one of the protrusions.
12. The method according to claim 8 , wherein the planarization layer includes a transparent organic interlayer dielectric sublayer.
13. The method according to claim 8 , further comprising a step of forming a color filter; wherein a distance between a top of each of the protrusions and the outermost surface is shorter than a distance between a top of the color filter and the outermost surface.
14. The method according to claim 8 , further comprising a step of forming a color filter; wherein a boundary of the filter on a side of each of the protrusions is superposed on a boundary of the planarization layer on a side of each of the protrusions.
15. A LCD device comprising:
a first substrate;
a second substrate coupled with the first substrate to be opposite to each other at a gap; and
a liquid-crystal layer formed in the gap;
wherein the first substrate comprises:
a transparent plate;
switching elements for respective pixels, formed on the plate;
protrusions for the respective pixels, formed on the plate in such a way as to protrude to a vicinity of an outermost surface of the substrate;
each of the protrusions raising an electrode of a corresponding one of the switching elements to the vicinity of the outermost surface in a corresponding one of the pixels;
a planarization layer formed in such a way as to cover the switching elements, the protrusions, and the electrodes of the elements in all the pixels, a surface of the planarization layer forming the outermost surface, the planarization layer having at least one contact holes formed over each corresponding protrusion, partially exposing the electrodes;
pixel electrodes for the respective pixels, formed on the outermost surface; and
each of the pixel electrodes being contacted with a corresponding one of the electrodes of the switching elements in the vicinity of the outermost surface.
16. The substrate according to claim 1 , further comprising an interlayer dielectric layer covering the switching elements and the protrusions, the interlayer dielectric layer being located between the switching elements and protrusions, and the planarization layer, the surface of the planarization layer is in a same level as a surface of the interlayer dielectric layer on the protrusions.
17. The substrate according to claim 16 , wherein the at least one contact hole is formed to penetrate is formed to penetrate the interlayer dielectric layer over each corresponding protrusion.
18. The method according to claim 8 , further comprising the step of forming an interlayer dielectric layer covering the switching elements and the protrusions, the interlayer dielectric layer being located between the switching elements and protrusions, and the planarization layer, the surface of the planarization layer is in a same level as a surface of the interlayer dielectric layer on the protrusions.
19. The method according to claim 18 , wherein the at least one contact hole is formed to penetrate is formed to penetrate the interlayer dielectric layer over each corresponding protrusion.