A method of forming a metal pattern includes disposing a gate metal layer on a substrate; disposing a photoresist layer on the gate metal layer; etching portions of the photoresist layer to form a first photo pattern; etching portions of the gate metal layer to form a gate pattern including a gate electrode, in which the gate metal layer is patterned using the first photo pattern as a mask; ashing an end portion of the first photo pattern to form a second photo pattern; disposing a first gate insulating layer over the substrate and the second photo pattern; removing the second photo pattern and a portion of the first gate insulating layer disposed over the second photo pattern; and disposing a second insulating layer over the gate pattern and the remaining portions of the first gate insulating layer.