Patent ID: 8420461

Claim:
A manufacturing method for a field-effect transistor, comprising the steps of: forming a first insulation film over a crystalline semiconductor film; patterning the first insulation film to form a gate insulation film over a portion of the crystalline semiconductor film; oxidizing a surface of the crystalline semiconductor film with an oxidizing water solution to form an oxide film; forming a conductive film over the oxide film and the gate insulation film, the conductive film comprising a semiconductor film containing an impurity having one conductivity type; patterning the conductive film to form a gate electrode, a source electrode, a drain electrode; and heating the crystalline semiconductor film, the oxide film, the gate insulation film, the gate electrode, the source electrode, and the drain electrode in an inert gas ambient at a temperature of from 800° C. to 1050° C. for a time period of from 30 minutes to 4 hours.