Patent ID: 6740456
Filing Date: 2004-05-25
Classification: G03F

Abstract:
A method of correcting a photomask, comprising:preparing a photomask substrate with a mask pattern including a phase shift pattern; forming a reference hole by removing a part of the mask pattern; applying an ion beam from an ion beam source to an area including the reference hole to allow secondary charged particles to be released from the reference hole; obtaining a position of the reference hole by detecting the secondary charged particles by a detector; calculating a positional relationship between the obtained position of the reference hole and a position of a defect of the mask pattern; and correcting the defect by applying an ion beam from the ion beam source to the defect, based on the calculated positional relationship, wherein a pattern of the reference hole, as viewed in a direction perpendicular to a top surface of the photomask substrate, is substantially rectangular, and a longitudinal direction of the rectangular pattern is parallel to a longitudinal direction of the phase shift pattern.