Thin film transistor and method of manufacturing the same

A method of manufacturing a thin film transistor, the method comprising:

• forming a first gate electrode on a substrate;
• forming a first insulating film on the substrate on which the first gate electrode is formed;
• laminating a semiconductor material layer and a metal layer on the first insulating film;
• patterning the semiconductor material and the metal layer in the same process to form a semiconductor layer, a source electrode and a drain electrode;
• forming a first hole in the first insulating film exposed by the patterning of the semiconductor material and the metal layer, wherein the first hole exposes a part of the first gate electrode;
• forming a second insulating film on the substrate on which the source electrode and the drain electrode are formed, wherein the second insulating film fill the first hole and covers the part of the first gate electrode;
• forming a second gate electrode on the first gate electrode, wherein the second insulating film is interposed between the first gate electrode and the second gate electrode;
• forming a third insulating film on the substrate on which the second gate electrode is formed;
• forming a contact hole by etching the second and third insulating films to expose the part of the first gate electrode covered by the second insulating film and a part of the second gate electrode;
• and
• forming a connection electrode in the first contact hole to connect electrically the part of the first gate electrode and the part of the second gate electrode.