Berlin 2008 – scientific programme
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DS: Fachverband Dünne Schichten
DS 17: Poster: Trends in Ion Beam Technology, Magnetism in Thin Films, Functional Oxides, High-k Dielectric Materials, Semiconductor Nanophotonics, Nanoengineered Thin Films, Layer Deposition Processes, Layer Growth, Layer Properties, Thin Film Characterisation, Metal and Amorphous Layers, Application of Thin Films
DS 17.21: Poster
Tuesday, February 26, 2008, 09:30–13:30, Poster A
Low-energy ion beam smoothing of Si surfaces — •Frank Frost, Bashkim Ziberi, and Bernd Rauschenbach — Leibniz-Institut für Oberflächenmodifizierung e. V.
In addition to nanostructuring of various surfaces via self-organized pattern formation, low-energy ion beam erosion can be used as an alternative process for surface smoothing and the preparation of ultra-smooth surfaces. In this work, the surface smoothing of Si surfaces by Ar+ ion beams (ion energy ≤ 2000 eV) was analyzed. Atomic force microscopy (AFM) has been used to systematically investigate the topography evolution of the surfaces with respect to different process parameters. The surface roughness was quantitatively characterized by the first order (rms roughness) and second order (power spectral density - PSD) statistical quantities. Based on the time evolution of these roughness parameters the relevant surface relaxation mechanisms responsible for surface smoothing have been discussed. Especially, it is shown that (i) smoothing can dominate for normal and near-normal ion incidence, (ii) if smoothing occurs, the minimum achievable surface roughness is limited by atomic noise, (iii) for low-energy Ar+ ion beam erosion of Si surfaces ballistic drift (atomic transport parallel to surface) and ballistic diffusion are the dominant relaxation mechanisms, (iv) secondary sputter effects caused by backscattered projectile ions and sputtered Si atoms have a great impact on the topography evolution, and (v) smoothing by atomic ballistic drift is the most efficient smoothing process at short lateral length scales at normal and near normal ion incidence, respectively.