A method for fabricating a thin film transistor for an LCD device is presented that uses six mask processes. Portions of a semiconductor layer formed on a substrate are doped with first and second impurities in different regions. A conductive layer is deposited and the conductive and semiconductor layers patterned together by diffraction exposure using a diffraction pattern mask to define source and drain regions and an activate region. Ashing is performed and portions of the conductive layer removed to form the source, drain and channel. A gate insulating layer is formed on the substrate and gates are formed on the gate insulating layer. A passivation film is formed on the substrate and a pixel contact hole exposing one of the drains is etched. A pixel electrode is then deposited such that the pixel electrode is connected to the drain through the pixel contact hole.