Patent ID: 6388386
Filing Date: 2002-05-14
Classification: B23K,H01L

Abstract:
A thin film transistor comprising:a semiconductor thin film; a gate insulating film stacked on one surface of said semiconductor thin film; and a gate electrode stacked on said semiconductor thin film via said gate insulating film; said semiconductor thin film is obtained by forming amorphous silicon or poly-crystal silicon having a relatively small grain size on a substrate, and irradiating the amorphous silicon or poly-crystal silicon having a relatively small grain size with the laser beam to crystallize the amorphous silicon or poly-crystal silicon having a relatively small grain size into poly-crystal silicon having a relatively large grain size; and the crystallization of said semiconductor thin film is performed by dividing the surface of the substrate into a plurality of division regions, and shaping a laser beam to adjust an irradiation region of the laser beam such that one of the division regions is collectively irradiated with one shot of the laser beam; irradiating one of the division regions with the laser beam while optically modulating the intensity of the laser beam such that a cyclic light-and-dark pattern is projected on the irradiation region, and irradiating the same division region by at least one time after shifting the pattern such that the light and dark portions of the pattern after shifting are not overlapped to those of the pattern before shifting; and shifting the irradiation region of the laser beam to the next division region, and repeating the crystallization for the division region.