DEFECT INSPECTION METHOD OF PHOTOMASK

摘要

PROBLEM TO BE SOLVED: To provide a defect inspection method of a photomask which is capable of improving detection sensitivity of the defect in the photomask in which a translucent film and a light-shielding film pattern are formed on a transparent substrate.SOLUTION: A defect inspection method of a photomask including a transparent substrate, a translucent film and a light-shielding film comprises: a first shading correction process of setting offset and gain of an imaging sensor based on a gradation target value of a specified black region and white region in a mask pattern such that luminance of the black region and the white region falls within a predetermined gradation region; a first image signal acquisition process of irradiating the photomask with inspection light in a wavelength region where a difference of transmittance between the black region and the white region in the mask pattern becomes a specified value or more, and imaging an optical image of the mask pattern in the imaging sensor to convert the image into an image signal; and a first inspection process of inspecting a defect of the photomask based on the image signal acquired in the first image signal acquisition process.