Patent ID: 7550328

Claim:
A method for production of a thin-film semiconductor comprising: a first step to form a gate electrode on a substrate; a second step to form a gate insulating film of silicon oxynitride on said substrate in such a way as to cover said gate electrode; a third step to form a semiconductor thin film on said gate insulating film; and a fourth step to perform heat treatment in an oxygen-containing oxidizing atmosphere for modification through oxygen binding with oxygen-deficient parts in said silicon oxynitride film constituting said gate insulating film, wherein the fourth step grows a thermal oxide film on the surface of said semiconductor thin film which has been formed by said heat treatment in the third step, and wherein fourth step is followed by an additional step to form a source-drain by patterning from said thermal oxide film in a shape overlapping said gate electrode and by further pattering from a semiconductor thin film containing impurities, said source-drain being in contact with said semiconductor thin film and said patterning being performed at a position on said semiconductor thin film under which said gate electrode exists.