Patent ID: 8486812

Claim:
A method for fabricating a polycrystalline silicon thin film out of amorphous silicon using laser, comprising: placing a mask having mask patterns forming laser transmission regions and laser non-transmission regions on a semiconductor layer; scanning a first laser beam through the mask onto a first area of the semiconductor layer, while a relative position of the mask with respect to the semiconductor layer is fixed at a first location; shifting the mask from the first location to a second location, on the basis of an axis parallel to a predetermined central axis and without radiating a laser beam onto the semiconductor layer after radiating the first laser beam; and scanning a second laser beam through the shifted mask and across a second area of the semiconductor layer, while the relative position of the mask with respect to the semiconductor layer is fixed at the second location, wherein the laser transmission regions exist asymmetrically on the basis of a laser scanning directional axis, and the laser transmission regions exist symmetrically on the basis of a predetermined central axis, wherein the laser transmission regions and the laser non-transmission regions are alternately positioned, wherein a laser transmission region has a structure in which laser transmission regions partially overlap in a direction perpendicular to the laser scanning directional axis when the mask is shifted the distance based on the axis parallel to the predetermined central axis, wherein a distance of the overlap between laser transmission regions is shorter than a width of the laser transmission region in a direction perpendicular to the laser scanning directional axis, wherein at least one laser transmission region is spaced apart by a different distance from the two other adjacent transmission regions disposed in a direction perpendicular to the laser scanning directional axis, the at least one laser transmission region is disposed between the two other adjacent transmission regions, and the at least one laser transmission region and the two other adjacent transmission regions are three successive laser transmission regions, wherein the laser transmission regions comprise a first laser transmission region of a line shaped pattern, a second laser transmission region of a line shaped pattern, and a third laser transmission region of a line shaped pattern, and wherein the length of the third laser transmission region is greater than the sum of the length of the first laser transmission region and the length of the second laser transmission region.