Method of laser annealing using linear beam having quasi-trapezoidal energy profile for increased depth of focus

摘要

A linear pulse laser beam to be applied to an illumination surface is so formed as to have, at the focus, an energy profile in the width direction which satisfies inequalities 0.5L 1<= L 2<= L 1 and 0.5L 1<= L 3<= L 1 where assuming that a maximum energy is 1, L 1 is a beam width of two points having an energy of 0.95 and L 1 + L 2 + L 3 is a beam width of two points having an energy of 0.70, L 2 and L 3 occupying two peripheral portions of the beam width. According to another aspect of the invention, a compound-eye-like fly-eye lens for expanding a pulse laser beam in a sectional manner is provided upstream of a cylindrical lens for converging the laser beam into a linear beam.