Patent ID: 7037811

Claim:
A method for manufacturing a semiconductor device comprising: forming a semiconductor film comprising amorphous silicon on an insulating surface; providing said semiconductor film with a metal containing material for promoting crystallization of said semiconductor film; crystallizing said semiconductor film by heating; irradiating the crystallized semiconductor film with laser light so as to distribute the metal in the crystallized semiconductor film; removing the distributed metal from the crystallized semiconductor film by gettering after the irradiation of the laser light; forming a semiconductor island having a tapered shape by patterning the crystallized semiconductor film, said tapered shape having an angle within a range of 20° to 50° between a side thereof and an underlying surface; forming a first gate insulating film over the semiconductor island wherein the first gate insulating film comprises silicon oxide; forming a second gate insulating film over the first gate insulating film wherein the second gate insulating film comprises silicon oxide nitride; forming a gate electrode over the semiconductor island with the first gate insulating film and the second gate insulating film therebetween; and forming at least a source region and a drain region in the semiconductor island.