title: At-wavelength inspection of sub-40 nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy.
abstract: A new at-wavelength inspection technology to probe nanoscale defects buried underneath Mo/Si multilayers on an extreme ultraviolet (EUV) 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 an ~13.5 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 edge visibility of the phase defects, which is explained in terms of a standing wave enhanced image contrast at resonant EUV illumination.
authors.affiliation: Faculty of Physics, Ludwig Maximilians University, Am Coulombwall 1, D85748 Garching, Germany. Jingquan.Lin@physik.uni-muechen.de
authors.forename: Jingquan
authors.initials: J
authors.lastname: Lin
authors.forename: Nils
authors.initials: N
authors.lastname: Weber
authors.forename: Jochen
authors.initials: J
authors.lastname: Maul
authors.forename: Stefan
authors.initials: S
authors.lastname: Hendel
authors.forename: Karsten
authors.initials: K
authors.lastname: Rott
authors.forename: Michael
authors.initials: M
authors.lastname: Merkel
authors.forename: Gerd
authors.initials: G
authors.lastname: Schoenhense
authors.forename: Ulf
authors.initials: U
authors.lastname: Kleineberg