Lin, Jingquan; Kleineberg, Ulf (Faculty of Physics, Ludwig Maximilians University, Am Coulombwall 1, D-85748 Garching, Munich, Germany)
Weber, Nils; Merkel, Michael (Focus GmbH, Neukirchner Str.2, D-65510 Huenstetten-Kesselbach, Germany)
Maul, Jochen; Schoenhense, Gerd (Institute of Physics, Mainz University, Staudinger Weg7, D-55099 Mainz,Germany)
Rott, Karsten; Hendel, Stefan (Faculty of Physics, Bielefeld University, Universitaetstr.25, D-33615 Bielefeld, Germany)
A new actinic mask inspection technology to probe nano-scaled defects buried underneath a Mo/Si multilayer reflection coating of an Extreme Ultraviolet Lithography mask blank has been implemented using EUV Photoemission Electron Microscopy (EUV-PEEM). EUV PEEM images of programmed defect structures of various lateral and vertical sizes recorded at around 13 nm wavelength show that 35 nm wide and 4 nm high buried line defects are clearly detectable. The imaging technique proves to be sensitive to small phase jumps enhancing the visibility of the edges of the phase defects which is explained in terms of a standing wave enhanced image contrast at resonant EUV illumination.