Adaptive optic off-axis metrology

摘要

A metrology source and sensor arrangement are placed off-axis adjacent to and preferably coplanar with a reticle and target, respectively in a catoptic optical system suitable for EUV imaging. On-axis aberrations are derived by modelling of the optical system from off-axis metrology output. Adaptive optical elements are employed to minimize aberrations at acceptable levels for high precision and resolution exposures such as lithographic patterning.