title: Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation.
abstract: 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. XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window.
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.|Helmholtz-Institute Jena, Jena, Germany.
authors: Silvio
authors: S
authors: Fuchs
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.|SLAC National Accelerator Laboratory, Menlo Park, United States.
authors: Christian
authors: C
authors: Rödel
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.
authors: Alexander
authors: A
authors: Blinne
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.
authors: Ulf
authors: U
authors: Zastrau
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.|Helmholtz-Institute Jena, Jena, Germany.
authors: Martin
authors: M
authors: Wünsche
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.
authors: Vinzenz
authors: V
authors: Hilbert
authors: Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany.
authors: Leif
authors: L
authors: Glaser
authors: Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany.
authors: Jens
authors: J
authors: Viefhaus
authors: Joint Attosecond Science Lab, National Research Council of Canada, Ottawa, Canada.
authors: Eugene
authors: E
authors: Frumker
authors: Joint Attosecond Science Lab, National Research Council of Canada, Ottawa, Canada.
authors: Paul
authors: P
authors: Corkum
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.|Helmholtz-Institute Jena, Jena, Germany.
authors: Eckhart
authors: E
authors: Förster
authors: Institute of Optics and Quantum Electronics, Friedrich-Schiller-University Jena, Jena, Germany.|Helmholtz-Institute Jena, Jena, Germany.
authors: Gerhard G
authors: GG
authors: Paulus