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.

Date Published: 3 May 2007
PDF: 7 pages
Proc. SPIE 6533, 23rd European Mask and Lithography Conference, 65331R (3 May 2007); doi: 10.1117/12.736920

Published in SPIE Proceedings Vol. 6533:
23rd European Mask and Lithography Conference
Uwe F. W. Behringer, Editor(s)