Pixel electrode of LCD device having first, second and third metal layers and pixel electrode contact hole in which the first metal layer is exposed to, and the second metal layer although contacting the first metal layer, is not exposed to the pixel electrode
A method for manufacturing a pixel electrode contact structure of a thin-film transistors liquid crystal display is disclosed. First, a transparent substrate having a first insulating layer thereon is provided. Afterward, a first metal layer and a second metal layer are sequentially formed on the substrate and then be patterned by a halftone technology and an etching process, wherein the second metal layer is removed within the pixel electrode contact area. In the meantime, the drain lines of the thin-film transistor comprising the first metal layer and the second metal layer are formed. Next, a patterned passivation layer is formed on the substrate. Finally, a pixel electrode layer directly connecting the first metal layers within the pixel electrode contact structure is formed on the substrate. This invention provides the pixel electrode contact structure with low contact resistance and prevents the current leakage from the drain line to the storage capacitor.
1. A pixel electrode contact structure of a thin film transistor liquid crystal display device, comprising:
a transparent substrate having a third metal layer;
a first insulation layer formed on the third metal layer or on the transparent substrate;
a patterned metal line having at least a first metal layer and a second metal layer with an opening, wherein the first metal layer is located between the second metal layer and the first insulation layer, the first metal layer is exposed in the opening of the second metal layer,
a passivation layer having an Si-containing second insulation layer, an organic resin layer and a contact hole, wherein the second insulation layer is located between the first metal layer and the organic resin layer, the second insulation layer covers and is in contact with the first metal layer and the second metal layer outside the contact hole, and wherein the first metal layer but not the second metal layer is exposed in the contact hole; and
a transparent pixel electrode located on the passivation layer, and the transparent pixel electrode in the contact hole is electrically connected with the first metal layer exposed in the contact hole or the first metal layer.
2. The pixel electrode contact structure as claimed in claim 1 wherein the third metal layer is patterned, and the third metal layer is located between the first insulation layer and the transparent substrate.
3. The pixel electrode contact structure as claimed in claim 1 , wherein the third metal layer is the gate of a thin film transistor.
4. The pixel electrode contact structure as claimed in claim 1 , wherein the first metal layer is Ti.
5. The pixel electrode contact structure as claimed in claim 1 , wherein the second metal layer is Al.
6. The pixel electrode contact structure as claimed in claim 1 , wherein the opening of the second metal layer is formed though halftone by using a photoresist having first thickness, second thickness, and third thickness, the first thickness is the thickness of the photoresist located in the pixel electrode contact area, the second thickness is the thickness of the photoresist located over the conductive lines electrically connected with the drain or the source of thin film transistors, the second thickness is greater than the first thickness, and the third thickness is less than the first thickness.
7. The pixel electrode contact structure as claimed in claim 6 , wherein the photoresist layer is formed by using a mask having first portions, second portions, and third portions, the transparencies of the first portions, the second portions, and the third portions are different, and the transparency of the first portions ranges between the transparency of the second portions and the transparency of the third portion.
8. The pixel electrode contact structure as claimed in claim 7 , wherein the photoresist is a positive photoresist, the first portions are made of semi-transparent materials, the second portions are made of non-transparent materials, and the third portions are made of transparent materials.
9. The pixel electrode contact structure as claimed in claim 2 , further comprising an organic resin layer formed between the second insulation layer and the transparent pixel electrode.