Method of crystallizing a semiconductor thin film

Abstract

A method of crystallizing a semiconductor thin film moves a laser beam emitted by a pulse laser in a first direction to irradiate the semiconductor tin film with the laser beam for scanning. The laser beam is split into a plurality of secondary laser beams of a width smaller than the pitch of step feed, respectively having different energy densities forming a stepped energy density distribution decreasing from the middle toward the opposite ends thereof with respect to the direction of step feed. The energy density of the first secondary laser beam corresponding to the middle of the energy distribution is higher than a threshold energy density, i.e., the minimum energy density that will melt the semiconductor thin film to make the same amorphous, and lower than a roughening energy density, i.e., the minimum energy density that will roughen the surface of the semiconductor thin film, the energy density of each of the secondary laser beams on the front side of the first secondary laser beam with respect to the direction of step feed is lower than a melting energy density, i.e., the minimum energy density of each of the secondary laser beams on the back side of the first secondary laser beam with respect to the direction of step feed is higher than the melting energy density and lower than and nearly equal to the threshold energy density.