An approach for patterning and etching without a mask is provided in a manufacturing a thin-film transistor, a gate electrode, a gate insulating layer, a semiconductor layer, an ohmic contact layer and source metal layer of a substrate. A first photoresist pattern including a first photo pattern and a second photo pattern is formed using a digital exposure device by generating a plurality of spot beams, the first photo pattern is formed to a first region of the base substrate and has a first thickness, and the second photo pattern is formed to a second region adjacent to the first region, and has a second thickness and a width in a range of about 50% to about 60% of a diameter of the spot beam. The source metal layer is patterned to form a source electrode and a drain electrode, and the source electrode and the drain electrode are spaced apart from each other in the first region of an active pattern.