Apparatus for zone melting recrystallization of thin semiconductor film

An apparatus for zone melting a thin semiconductor film disposed on an insulating substrate of a composite, comprising:

• means for holding said composite;
• first laser means for generating a first laser beam which is absorbed by the semiconductor film to thereby heat the thin semiconductor film;
• first optical means, disposed between said first laser means and said holding means, for focusing said first laser beam on the thin semiconductor film;
• a first deflection device for deflecting the first laser beam emitted from said first optical means toward the thin semiconductor film;
• oscillation means, connected to said first deflection device, for oscillating said focused first laser beam at a predetermined frequency in a direction substantially perpendicular to the direction of movement of a melting zone of the thin semiconductor film to thereby form a linear thermal profile on the thin semiconductor film;
• a plurality of second lasers, each of which generates a second laser beam absorbed by the insulating substrate to thereby heat the insulating substrate;
• a plurality of second deflection devices, each of which respectively deflects the second laser beam generated by a corresponding second laser in such a manner that each of the second laser beams is deflected to different positions on the insulating substrate to thereby form a spread thermal profile which includes and said linear thermal profile and extends beyond said linear thermal profile;
• a first temperature detecting device for detecting a first temperature of a melted portion of the thin semiconductor film;
• a second temperature detecting device for detecting a second temperature of a portion of the thin semiconductor film, said portion being situated at a position separated by a predetermined distance in a scanning direction from a solidifying portion of the thin semiconductor film;
• a first controller, electrically connected to said first temperature detecting device and said first laser means, for controlling an output of said first laser means so that said first temperature is maintained within a first predetermined temperature range higher than the melting point of the thin semiconductor film;
• a plurality of second controllers, each electrically connected to the second temperature detecting device and a corresponding second laser, for controlling an output of each of said second lasers so that said second temperature is maintained within a second predetermined temperature range lower than the melting point of the thin semiconductor film;
• and
• means for relatively moving said holding means and said first and second laser beams in a predetermined direction.