Emulsion mask defect repair - by applying contoured UV beam of excimer laser

摘要

Defects in the emulsion layer of a photomask are repaired by irradiation of the defect with UV light in a shape to match the defect and by destroying the defect by this treatment. The UV beam of an excimer laser is used to pass through an aperture of suitable configuration. To correct a black spot defect (D) of the emulsion mask (7), the beam (2) of a laser oscillator (1) is expanded (3) and the UV component is reflected selectively (4) through an aperture (5x) of the plate (5) to project the shape of (5x) through a reproduction lens (6) on the mask. A lens (11) can be used to observe the spot through a semitransparent mirror (10). For the correction of white defects, a slightly adhesive resin (PVC, polyester, PU, epoxy resin) in an organic solvent is applied around the defective area.