Patent ID: 8598050

Claim:
A laser annealing method of performing an annealing treatment on a workpiece by irradiating the workpiece with a linear beam having a linear beam spot obtained by shaping laser light into a linear shape while moving the linear beam in a short-axis direction of the linear beam spot relative to the workpiece, wherein the laser annealing method comprises the steps of: (a) concentrating the linear beam of shaped laser light onto a surface of the workpiece by using a condensing lens; (b) performing irradiation of the workpiece with the linear beam with relative movement in the short-axis direction of the linear beam spot on two rows while shifting the linear beam spot in a long-axis direction of the linear beam so that beam irradiation areas of adjacent rows partially overlap each other; (c) controlling an overlap ratio of adjacent two rows by shielding, during irradiation of the linear beam, portions corresponding to edges in the long-axis direction of the linear beam spot concentrated onto the surface of the workpiece using a mask disposed on an optical path of the laser light between the condensing lens and the workpiece, and the mask is operated so as to periodically increase and decrease an amount of shielding; and d) regulating energy intensity at the beam edges so as not to increase the energy intensity due to diffracted light at the mask while monitoring an energy distribution in the long-axis direction of the linear beam using a profile monitor; wherein the control of the overlap ratio at the beam edges by the mask is performed on a beam edge at a side corresponding to a seam portion when at least one of the adjacent two rows is irradiated; and wherein uniformity of crystallinity in the seam portion is not sacrificed so that the seam portion is not visually recognizable.