title: Mass Absorption Coefficient of Tungsten and Tantalum, 1450 eV to 2350 eV: Experiment, Theory, and Application.
abstract: The mass absorption coefficients of tungsten and tantalum were measured with soft x-ray photons from 1450 eV to 2350 eV using an undulator source. This region includes the M3, M4, and M5 absorption edges. X-ray absorption fine structure was calculated within a real-space multiple scattering formalism; the predicted structure was observed for tungsten and to a lesser degree tantalum as well. Separately, the effects of dynamic screening were observed as shown by an atomic calculation within the relativistic time-dependent local-density approximation. Dynamic screening effects influence the spectra at the 25 % level and are observed for both tungsten and tantalum. We applied these results to characterize spatially-resolved spectra of a tungsten integrated circuit interconnect obtained using a scanning transmission x-ray microscope. The results indicate tungsten fiducial markers were deposited into silica trenches with a depths of 50 % and 60 % of the markers' heights.
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8410.
authors.forename: Zachary H
authors.initials: ZH
authors.lastname: Levine
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8410.
authors.forename: Steven
authors.initials: S
authors.lastname: Grantham
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8410.
authors.forename: Charles
authors.initials: C
authors.lastname: Tarrio
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave. Argonne, IL 60439.
authors.forename: David J
authors.initials: DJ
authors.lastname: Paterson
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave. Argonne, IL 60439.
authors.forename: Ian
authors.initials: I
authors.lastname: McNulty
authors.affiliation: IBM Microelectronic Division, Essex Junction, VT 05452.
authors.forename: T M
authors.initials: TM
authors.lastname: Levin
authors.affiliation: Department of Physics, Box 351560 University of Washington, Seattle, WA 98195-1560.
authors.forename: Alexei L
authors.initials: AL
authors.lastname: Ankudinov
authors.affiliation: Department of Physics, Box 351560 University of Washington, Seattle, WA 98195-1560.
authors.forename: John J
authors.initials: JJ
authors.lastname: Rehr
keywords: Integrated circuit interconnect; M3 edge; M4 edge; M5 edge; mass absorption; microspectroscopy; tantalum; transmission; tungsten