Patent ID: 8871590

Claim:
A method of fabricating a thin film transistor array substrate to improve the aperture ratio of a pixel region, comprising: forming a first metal layer on a substrate with a display area and a non-display area, and patterning the first metal layer into a gate electrode, a gate line, and a first common electrode that are arranged on the display area of the substrate, and a gate pad on the non-display area of the substrate through a first mask process; sequentially forming a gate insulation film, a semiconductor layer, and a second metal layer on the substrate and forming source and drain electrodes, a second storage electrode, a channel layer, and a data line from the second metal layer and the semiconductor layer through a second mask process; sequentially forming a protective film and an organic insulation film on the substrate, and patterning the patterning the organic insulation film by performing exposing and developing steps according to a third mask process; sequentially performing first and second etching steps in which the patterned organic insulation film is used as an etch mask by using etching gases with different oxygen content ratios, in order to form contact holes in a drain electrode region, a gate pad region, and a data pad region; and sequentially forming a third metal layer and the fourth metal layer on the organic insulation film with the contact holes, and then patterning the third and fourth metal layers into a pixel electrode and a second common electrode through the fourth mask process, and wherein the organic insulation film is disposed between the pixel electrode and the second common electrode and the protective film in the pixel region.