Thin-film transistor

A thin film transistor comprising:

• a substrate;
• a gate including a double-layered structure having a first metal layer on the substrate and a second metal layer on the first metal layer, the first metal layer including aluminum, the first metal layer being wider than the second metal layer by about 1 to 4 μm;
• a first insulating layer on the substrate including the gate;
• a semiconductor layer on a portion of the first insulating layer;
• an ohmic contact layer on the semiconductor layer;
• a source electrode and a drain electrode on the ohmic contact layer and extending onto the first insulating layer;
• a second insulating layer on the semiconductor layer, the source and drain electrodes and the first insulating layer, the second insulating layer having a contact hole over one of the source and drain electrode;
• and
• a transparent conductive layer on the second insulating layer and contacting the one of the source and drain electrodes through the contact hole;
• wherein the first metal layer has substantially a first trapezoidal shape having first, second, third and fourth sides, the first and second sides being substantially parallel to each other,
• wherein the second metal layer has substantially a second trapezoidal shape having fifth, sixth, seventh and eighth sides, the fifth and sixth sides being substantially parallel to each other,
• wherein the fifth side is contacting the second side and being substantially in a central portion of the second side, the fifth side being shorter than the second side at both ends to leave exposed first and second end portions of the second side, and
• wherein the third and fourth sides have first and second slopes and the seventh and eighth sides have third and fourth slopes.