Thin film transistor and manufacturing method of thin film transistor

A thin film transistor manufacturing method, comprising:

• a first step of forming a refractory metal film on one main surface of a substrate and of forming a gate electrode by etching the refractory metal film into a specific pattern;
• a second step of forming a gate insulating film on said substrate so as to cover sa d gate electrode and of forming a semiconductor film on the gate insulating film;
• a third step of forming an insulating film with a predetermined film thickness on said semiconductor film and of forming a stopper by etching the insulating film into a pattern corresponding to said gate electrode;
• a fourth step of forming an interlayer insulating film on said semiconductor film so as to cover said stopper;
• and a fifth step of heating said semiconductor film and said interlayer insulating film to a predetermined temperature and of introducing hydrogen ions included in said interlayer insulating film into said semiconductor film,
• wherein said third step including a step of forming a silicon oxide film as said insulating film to have a film thickness of 800 angstroms to 1200 angstroms.