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Title: Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation

Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1 μm, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengths corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18 nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8 nm. As a result, XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window.
 [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6] ;  [1] ;  [1]
  1. Friedrich-Schiller-Univ. Jena, Jena (Germany); Helmholtz-Institute Jena, Jena (Germany)
  2. Friedrich-Schiller-Univ. Jena, Jena (Germany); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. Friedrich-Schiller-Univ. Jena, Jena (Germany)
  4. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
  5. National Research Council of Canada, Ottawa, ON (Canada); Ben-Gurion Univ., Beer-Sheva (Israel)
  6. National Research Council of Canada, Ottawa, ON (Canada)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Nature Publishing Group
Research Org:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
imaging and sensing; microscopy; X-rays