Patent ID: RE42139

Claim:
A semiconductor device comprising: a supporting substrate comprising single crystalline silicon; an insulating layer comprising silicon oxide at a surface of the supporting substrate; an island-like single crystalline semiconductor layer comprising silicon formed on an the insulating layer comprising silicon oxide over a supporting substrate , the single crystalline semiconductor layer having at least a channel formation region and source and drain regions; a gate insulating film formed on the single crystalline semiconductor layer; a gate electrode formed over the channel formation region with the gate insulating film interposed therebetween wherein the gate electrode includes a metal layer which contacts the gate insulating film; etching stoppers silicon oxide films formed on side surfaces of the gate electrode; side walls formed adjacent to the side surfaces of the gate electrode with the etching stoppers silicon oxide films interposed therebetween; and an insulating film comprising silicon nitride formed over the single crystalline semiconductor layer and the gate electrode , wherein the island - like single crystalline semiconductor layer comprises part of a single crystalline semiconductor substrate different from the supporting substrate .