Patent ID: 7078322

Claim:
A method of manufacturing a thin film transistor, comprising: forming an amorphous semiconductor film over a substrate; running a laser beam relative to the substrate to irradiate the amorphous semiconductor film with the laser beam and form a crystalline semiconductor film; and etching the crystalline semiconductor film to form an active layer, wherein the width of a region irradiated with the laser beam is the sum of an effective irradiation region width D, a width d of a region on the left side of the effective irradiation region, and a width d of a region on the right side of the effective irradiation region, and wherein the crystalline semiconductor film used for the active layer is formed excluding a region within a distance L, which is expressed by n(D+2d)−d≦L≦n(D+2d)+d and 0≦L (n is an integer, 0≦n) when V=0, V being the overlap width of adjacent laser beams during laser beam scanning, L being the distance from the origin in the direction perpendicular to the laser beam scanning direction, the origin being one point in an end of the region irradiated with the laser beam on an irradiation object.