Mass Absorption Coefficient of Tungsten and Tantalum, 1450 eV to 2350 eV: Experiment,Theory, and Application |
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| Authors: | Zachary H Levine Steven Grantham Charles Tarrio David J Paterson Ian McNulty T M Levin Alexei L Ankudinov John J Rehr |
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| Affiliation: | National Institute of Standards and Technology, Gaithersburg, MD 20899-8410;Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave. Argonne, IL 60439;IBM Microelectronic Division, Essex Junction, VT 05452;Department of Physics, Box 351560 University of Washington, Seattle, WA 98195-1560 |
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| 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. |
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| Keywords: | Integrated circuit interconnect M3 edge M4 edge M5 edge mass absorption microspectroscopy tantalum transmission tungsten |
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