Abstract: A method of fabricating a thin film transistor array substrate for a liquid crystal display includes the step of forming a gate line assembly with gate lines, gate electrodes and gate pads. After laying a plurality of layers on the substrate, a photoresist film is deposited onto the layers. The photoresist film is first exposed to light at a first light exposing unit, and secondly exposed to light at a second light exposing unit such that the photoresist film has three portions of different thickness. The photoresist pattern, and some of the underlying layers are etched to form a data line assembly, a semiconductor pattern, and an ohmic contact pattern. The data line assembly includes data lines, source and drain electrodes, and data pads. The remaining photoresist film is removed, and a protective layer is formed on the substrate.