Method of crystallizing a semiconductor thin film

A method of melt growth system of crystallizing a semiconductor thin film by irradiating the semiconductor thin film with a laser beam emitted by a pulse laser, characterized in that:

• the laser beam emitted by the pulse laser is moved in irradiating the semiconductor thin film in a first direction for scanning and in a second direction for step feed;
• the laser beam emitted by the pulse laser is split into a plurality of secondary laser beams of a width smaller than the pitch of step feed, respectively having energy densities forming a stepped energy density distribution decreasing from the middle toward the opposite ends thereof with respect to the second direction;
• the energy density E.sub.D.spsb.1 of the first secondary laser beam corresponding to the middle of the energy density distribution is higher than a threshold energy density E.sub.Dth, that is, the minimum energy density that will melt the semiconductor thin film to make the semiconductor thin film amorphous, and lower than a roughening energy density E.sub.DR, that is, 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 second direction is lower than a melting energy density E.sub.DM, that is, the minimum energy density that will melt the semiconductor thin film;
• and
• the energy density of each of the secondary laser beams on the back side of the first secondary laser beam with respect to the second direction is higher than the melting energy density E.sub.DM and lower than and nearly equal to the threshold energy density E.sub.Dth.