Method for manufacturing semiconductor thin film

A method for manufacturing a semiconductor thin film, comprising:

• a first step of forming a first semiconductor thin film on a single-crystal substrate;
• a second step of selectively forming a first mask film with a plurality of openings therein on the first semiconductor thin film;
• a fourth step of subjecting the first semiconductor thin film with the first mask film formed thereon to a heat treatment in an oxidizing atmosphere to oxidize portions of the first semiconductor thin film that are exposed through the openings of the first mask film and a vicinity thereof, thereby forming a plurality of first oxidized regions in the first semiconductor thin film;
• a fifth step of removing the first mask film to expose the first semiconductor thin film and then forming a second semiconductor thin film on the exposed first semiconductor thin film so as to cover the plurality of first oxidized regions;
• a sixth step of forming a second mask film so that the second mask film has a plurality of openings for exposing therethrough portions of the second semiconductor thin film that are above portions of the first semiconductor thin film interposed by the first oxidized regions;
• a seventh step of subjecting the second semiconductor thin film with the second mask film formed thereon to a heat treatment in an oxidizing atmosphere to oxidize portions of the second semiconductor thin film that are exposed through the openings of the second mask film and a vicinity thereof, thereby forming a plurality of second oxidized regions in the second semiconductor thin film;
• and an eighth step of removing the second mask film to expose the second semiconductor thin film and then forming a third semiconductor thin film on the exposed second semiconductor thin film so as to cover the plurality of second oxidized regions.