Focus-height measurement i.e. isotropic focus-height measurement, correcting method, involves determining focus-height error correction value, and correcting focus-height measurement using value to provide corrected measurement

摘要

The method involves determining a focus (Z)-height measurement based on a focus region of interest, and determining orientation angle content characteristics for an image content in the region. Z-height error calibration data includes a characterization of a variation in Z-height measurement results that are accessed based on the region. A Z-height error correction value is determined based on the characteristics for the image content and the calibration data. The Z-height measurement is corrected using the correction value to provide the corrected Z-height measurement. An independent claim is also included for a calibration target comprising a flat substrate.