Soft X-ray and EUV Reflectometry
Polychromatic Angle-resolving Non-destructive Tool for Extreme-ultraviolet Reflectometry (PANTER)Fraunhofer ILT | Makysm Tryus
Extreme Ultraviolet (EUV) radiation differs from radiation of other spectral ranges mainly by its strong interaction with matter. This feature of EUV radiation is beneficial for applications where impact of this interaction is of particular importance. A use of this radiation allows developing a surface-sensitive optical technique for studying thin films and layered structures – EUV Reflectometry.
By measuring the specular reflectivity of a layered sample at various wavelengths and incidence angles, one can determine the key parameters of every layer, namely thickness and density. Moreover, an insight into chemical bonds and local symmetry can be obtained from the near-edge fine structures (NEXAFS) in the reflectivity spectra.
Laboratory plasma-based EUV radiation sources offer nowadays fast and compact solutions for many metrology techniques that have been previously available exclusively at synchrotron facilities. Our reflectometer setup utilizes a discharge-produced plasma source with working gas mixture of Kr and Xe which emits EUV in a quasi-continuous wavelength range from 9 to 17 nm.
Simultaneous acquisition of spectra before and after the reflection from the sample allows to make faster measurements and to directly account for the source intensity fluctuations. Novel realization of the multi-angle setup operation allows changing the grazing angle of illumination in the range between 2° and 15°. Such approach provides more reliable information about the sample structure, and reduces uncertainty in the analytical modelling process.
The next evolutionary step in the setup upgrade is going to provide spatially resolving reflectometry measurements that could allow reflectivity mapping of the sample surface at submillimeter-scale and also investigating small individual structures.
ReferencesFraunhofer ILT | Maksym Tryus
 M. Banyay, L. Juschkin, T. Bücker, P. Loosen, A. Bayer, F. Barkusky, S. Döring, C. Peth, K. Mann, H. Blaschke, I. Balasa and D. Ristau, "XUV metrology: surface analysis with extreme ultraviolet radiation", Proc. SPIE 7361, Damage to VUV, EUV, and X-Ray Optics II, 736113 (May 18, 2009).
 M. Banyay and L. Juschkin, “Table-top reflectometer in the extreme ultraviolet for surface sensitive analysis”, Applied Physics Letters, vol. 94, no. 6, Article ID 063507, 2009.
 M. Banyay and L. Juschkin, “Spectral Sharpening Algorithm for a Polychromatic Reflectometer in the Extreme Ultraviolet”, Applied Spectroscopy, Vol. 64, Issue 4, pp. 401-408 (2010).
 M. Banyay, L. Juschkin, E. Bersch, D. Franca, M. Liehr, A. Diebold “Cross characterization of ultrathin interlayers in HfO2 high-k stacks by angle resolved x-ray photoelectron spectroscopy, medium energy ion scattering, and grazing incidence extreme ultraviolet reflectometry”, J. Vac. Sci. Technol. A, 30 (2012), p. 041506.