Apparatus for repairing defects in emulsion masks by passing laser light through a variable shaped aperture

摘要

Defective portions, such as black dot defects, in an emulsion layer of an emulsion mask such as a photomask are repaired or removed by irradiating an ultraviolet laser beam from a laser oscillator, preferably an excimer laser. The laser beam is passed through an adjustable aperture for shaping and is then projected onto defective portions in dimensional alignment, whereby the defective portions are destroyed. In order to ensure that only the defective portions are destroyed, the image of the aperture projected on the emulsion layer is observed so as not to cover the emulsion mask where defective portions do not exist. Defective portions such as white defects can also be repaired by using additional procedure together with the irradiation of the laser beam.