Spectroscopic reflectometry in the extreme ultraviolet for critical dimension metrology

摘要

The authors report on critical dimension metrology on nanoscale gratings by means of laboratory-based spectroscopicreflectometry in the extreme ultraviolet (EUV). EUV reflectivity spectra of nanoscale gratings under grazing incidenceillumination and their dependency on the geometrical grating parameters are discussed. A laboratory-based setup tomeasure such spectra is introduced and its main features are presented. A nanoscale grating with a grating period below100 nm, consisting of multiple nanometer-size layers of materials, is experimentally investigated with the setup. Theexperimental results are consequently compared to a rigorous model fit of the reflectivity and thus the ability to model thegrating’s interaction with EUV radiation is shown.