Patent ID: 7381632

Claim:
A semiconductor thin film crystallization method comprising the steps of: irradiating a semiconductor thin film on a substrate with a first laser beam to form a striped first beam spot having a specified width and a specified length on the semiconductor thin film; irradiating the semiconductor thin film with a second laser beam to form a second beam spot having a shape containing the first beam spot on the semiconductor thin film; and moving the substrate relative to the two beam spots in a widthwise direction of the first beam spot to crystallize the semiconductor thin film on the substrate by the first and second laser beams, wherein the irradiation with the second laser beam is performed at least while the irradiation with the first laser beam is being performed, intensity of the second laser beam is maintained constant during a period from an emission start time to an emission end time, and light intensity of the second laser beam within the second beam spot is maintained constant at least over portions overlapping with the first beam spot.