Patent ID: 8053837

Claim:
A semiconductor device comprising: a transistor including: an island-like single crystalline semiconductor layer comprising silicon formed over a silicon substrate with a first silicon oxide film and a second silicon oxide film interposed therebetween, the island-like single crystalline semiconductor layer having at least a channel formation region and source and drain regions; a gate insulating film formed on the channel formation region; a gate electrode comprising polysilicon formed over the channel formation region with the gate insulating film interposed therebetween; and side walls formed adjacent to side surfaces of the gate electrode; and an interlayer insulating film comprising silicon nitride formed over the transistor, wherein an upper portion of the gate electrode and upper portions of the source and drain regions comprise a metal silicide, and wherein the island-like single crystalline semiconductor layer is in direct contact with the first silicon oxide film, the first silicon oxide film is in direct contact with the second silicon oxide film, and the second silicon oxide film is in direct contact with the silicon substrate, wherein the second silicon oxide film is thinner than the first silicon oxide film.