Open AccessThree-dimensional characterization of extreme ultraviolet mask blank defects by interference contrast photoemission electron microscopy
Author(s) -
Jingquan Lin,
Nils Weber,
M. Escher,
J. Maul,
Hyeuk Jin Han,
M. Merkel,
Stefan Wurm,
G. Schönhense,
Ulf Kleineberg
Publication year - 2008
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.16.015343
Subject(s) - extreme ultraviolet , extreme ultraviolet lithography , blank , optics , photoemission electron microscopy , materials science , interference (communication) , differential interference contrast microscopy , ultraviolet , interference lithography , wavelength , contrast (vision) , microscope , electron microscope , optoelectronics , microscopy , physics , laser , medicine , channel (broadcasting) , electrical engineering , alternative medicine , pathology , fabrication , composite material , engineering
A photoemission electron microscope based on a new contrast mechanism "interference contrast" is applied to characterize extreme ultraviolet lithography mask blank defects. Inspection results show that positioning of interference destructive condition (node of standing wave field) on surface of multilayer in the local region of a phase defect is necessary to obtain best visibility of the defect on mask blank. A comparative experiment reveals superiority of the interference contrast photoemission electron microscope (Extreme UV illumination) over a topographic contrast one (UV illumination with Hg discharge lamp) in detecting extreme ultraviolet mask blank phase defects. A depth-resolved detection of a mask blank defect, either by measuring anti-node peak shift in the EUV-PEEM image under varying inspection wavelength condition or by counting interference fringes with a fixed illumination wavelength, is discussed.