Patent ID: 7727913

Claim:
A method of crystallizing a semiconductor film comprising: splitting a pulse laser beam oscillated from a laser oscillator, and synthesizing the split pulse laser beams after the split pulse laser beams have propagated through optical paths different in optical path length; modulating the synthesized pulse laser beam into a pulse laser beam by a phase modulating element; and irradiating a non-single-crystal film formed on a substrate with the synthesized laser beam to crystallize the non-single-crystal film, wherein splitting the pulse laser beam and synthesizing the split pulse laser beams are performed using at least three optical splitting/synthesizing means arranged in order, and include sequentially splitting one pulse laser beam split by one optical splitting/synthesizing means by succeeding splitting/synthesizing means, and synthesizing the other pulse laser beam split by one optical splitting/synthesizing means with the other pulse laser beam split by preceding splitting/synthesizing means.