Thin film transistor and method of manufacturing the same

A thin film transistor, comprising on a substrate at least:

• a gate electrode;
• a gate insulating layer on the gate electrode;
• an oxide semiconductor layer on the gate insulating layer;
• a channel protection layer on the oxide semiconductor layer;
• and
• an insulating interlayer which contains hydrogen and has an intermediate region contacts with the channel protection layer and two outer regions, each of which contacts with the oxide semiconductor layer outside of the intermediate region, respectively,
• wherein the oxide semiconductor layer contains an amorphous In—Ga—Zn—O as a major component,
• wherein the channel protection layer has at least one layer containing a silicon oxide as a major component in contact with the oxide semiconductor layer,
• wherein the channel protection layer has a central part and two thinner end parts, each of which is thinner than the central part so as to be a hydrogen transmittance path from the insulating interlayer to the oxide semiconductor layer, and both of which sandwich the central part,
• and
• wherein the oxide semiconductor layer has, in a coplanar arrangement, a channel region underneath the central part of the channel protection layer, a source electrode underneath one of the two outer regions, a drain electrode underneath the other of the two outer regions, and each of two medium-resistance regions underneath each of the two thinner end parts, respectively.