A method of fabricating a thin-film transistor (TFT) substrate includes forming a gate electrode on a substrate; forming an insulating film on the gate electrode; forming an amorphous semiconductor pattern on the insulating film; and forming a source electrode separated from a drain electrode on the amorphous semiconductor pattern; forming a light-concentrating layer, which includes a protrusion, on the amorphous semiconductor pattern, the source electrode, and the drain electrode; and crystallizing at least part of the amorphous semiconductor pattern by irradiating light to the protrusion of the light-concentrating layer.