Laser irradiation apparatus, laser irradiation method, semiconductor device, and method of manufacturing a semiconductor device

摘要

To form a polycrystalline silicon film having a grain size of 1 mum or greater by means of laser annealing. A beam emitted from a laser apparatus ( 101 ) is split in two by a half mirror. The split beams are processed into linear shapes by cylindrical lenses ( 102 ) to ( 105 ), and ( 207 ), then simultaneously irradiate an irradiation surface ( 209 ). If an amorphous silicon film formed on a glass substrate is disposed on the irradiation surface ( 209 ), an area will be irradiated by both a linear shape beam entering from a front surface and a linear shape beam that has transmitted through the glass surface. Both linear shape beams irradiate the same area to thereby crystallize the amorphous silicon film.