Patent ID: 7427764

Claim:
A laser crystallization apparatus comprising an crystallization optical system which irradiates laser light to a thin film disposed on a substrate to form an image of the laser light thereon through an imaging optical system to melt and crystallize an irradiated region of the thin film, the apparatus comprising: a measurement light source which is disposed outside a light path of the laser light, and which emits imaging position measurement light to illuminate the irradiated region of the thin film; an imaging position measurement light illumination optical system which illuminates the imaging position measurement light on the irradiated region of the thin film through the imaging optical system to form an image of the imaging position measurement light on the thin film to detect a surface level thereof; a detecting unit which determines an imaging position shift between the surface level of the irradiated region of the thin film and an imaging plane of the imaging optical system based on the formed image of the imaging position measurement light on the irradiated region of the thin film; an imaging position correcting unit which corrects the surface level of the irradiated position of the thin film to a level with the imaging position shift being within a desired range, if the imaging position shift is out of predetermined range; and a control unit which controls an emission of the laser light from a laser light source, if the imaging position shift is within the predetermined range.