Patent ID: 8193045

Claim:
A manufacturing method of a thin film transistor having at least a gate electrode, a gate insulation film, an oxide semiconductor layer, a first insulation film, a source electrode, a drain electrode, and a second insulation film on a substrate, including: forming the gate electrode on the substrate; forming the gate insulation film on the gate electrode; forming a semiconductor layer including amorphous oxide on the gate insulation film; reducing the oxide semiconductor layer in resistance by forming the first insulation film on the oxide semiconductor layer in the atmosphere not including an oxidized gas; patterning the first insulation film to form contact holes; forming a source electrode layer in contact with the oxide semiconductor layer through one of the contact holes, and a drain electrode layer in contact with the oxide semiconductor layer through one of the contact holes; forming the source electrode and the drain electrode by patterning and allowing the first insulation film to be exposed; patterning the exposed first insulation film and allowing a channel region of the oxide semiconductor layer to be exposed; and increasing the channel region in resistance by forming the second insulation film on the surface including the channel region of the oxide semiconductor layer in the atmosphere including an oxidized gas.