METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a laser irradiation device which is capable of eliminating or drastically reducing the influence of a difference in a polarization state between pulse laser beams on a laser irradiator, when the pulse laser beams from two laser light sources are guided to the same optical path, to irradiate a body irradiated by laser.SOLUTION: The laser irradiation device including laser light sources 3 and 4 and an optical path synthesizing optical element 7 guiding the pulse laser beams from these light sources onto the same optical path includes a polarization control element 9 controlling the polarization states of the pulse laser beams from the optical path synthesizing optical element 7. The polarization control element 9 includes first and second polarization control parts 13 and 15 through which the beam components of the pulse laser beams pass respectively. The beam component after passing through the first polarization control part 13 and the beam component after passing through the second polarization control part 15 are made into the polarization states different from each other. The beam components being in the polarization states different from each other are superimposed on each other on the laser irradiation surface of the body irradiated by laser.