DEFECT INSPECTING METHOD, SORTING METHOD AND PRODUCING METHOD FOR PHOTOMASK BLANK

摘要

Disclosed is a method of inspecting a defect present at a surface portion of a photomask blank which includes an optical film, and a thin film. The method includes: selecting and designating an inspection treatment procedure and a criterion for determination of rugged shape of the defect which correspond to modes of the optical film and the thin film of the photomask blank; applying inspection light to a region including the defect while maintaining a distance between the defect and an objective lens of an inspecting optical system, based on the designated inspection treatment procedure, and collecting reflected light from the region irradiated with the inspection light, as a magnified image of the region, through the inspecting optical system; and determining the rugged shape of the defect, from light intensity distribution of the magnified image, based on the designated criterion for determination.

主权项

1. A method of inspecting a defect present at a surface portion of a photomask blank by use of an inspecting optical system, the photomask blank including an optical film formed on a substrate, and a thin film formed in contact with a side of the optical film opposite to the substrate, the thin film being formed as an outermost surface layer, the method comprising:
(A1) a step of preparing the photomask blank; (A2) a step of selecting and designating an inspection treatment procedure and a criterion for determination of rugged shape of the defect which correspond to mode of the optical film and the thin film of the photomask blank; (A3) a step of moving the photomask blank to move the defect into an observation position of the inspecting optical system, applying inspection light to a region including the defect while maintaining a distance between the defect and an objective lens of the inspecting optical system, based on the inspection treatment procedure designated in the step (A2), and collecting reflected light from the region irradiated with the inspection light, as a magnified image of the region, through the inspecting optical system; and (A4) a step of determining the rugged shape of the defect, from light intensity distribution of the magnified image, based on the criterion for determination designated in the step (A2).