Patent ID: 7078274

Claim:
A method for manufacturing a semiconductor device, comprising the steps of: forming a metal layer over a partial region of a transparent substrate; forming a buffer layer over almost the entire surface of the transparent substrate covering the metal layer in an order of a silicon nitride film and a silicon oxide film; forming a first amorphous semiconductor film above the buffer layer such that the first amorphous semiconductor film at least partially overlaps the formation region of the metal layer with the buffer layer therebetween so that the metal layer overlaps regions in which a source, a channel, and a drain of a thin film transistor are to be formed in a first region of the first amorphous semiconductor and simultaneously forming a second amorphous semiconductor film above the non-formation region of the metal layer; polycrystallizing the first and second amorphous semiconductor films through laser annealing to form a first polycrystalline semiconductor film and a second polycrystalline semiconductor film; and wherein the buffer layer alleviates thermal leakage caused by thermal conduction in the metal layer during polycrystallization of the first and second amorphous semiconductor films through laser annealing; and wherein the metal layer has a light shielding function for blocking light from a side near the metal layer to the thin film transistor to be formed.