Depth profiling of Mo/Si multi-nano-layers by DSIMS and HRTEM

Babor, Petr1; Potocek, Michal1; Voborny, Stanislav1; Polcak, Josef1; Prusa, Stanislav1; Kolibal, Miroslav1; Spousta, Jiri1; Dittrichova, Libuse1; Sobota, Jaroslav1; Bochnicek, Zdenek1; Roucka, Radek2; Kouvetakis, John2; Sikola, Tomas1 1Czech Republic; 2United States

Recently, a strong interest in ultra thin films with a thickness of a few nanometers (or even less), and their multilayers, has appeared. The preparation and analysis of such thin films are not straightforward. The main issues here are the selection of the preparation method to obtain ultra thin films of required quality and properties and the choice of a proper analytical method to find out desired information about them. It is obvious that surface and interfacial quality (e.g. roughness, composition) and layer profiles (composition, structure) of ultra thin films belong to the most critical parameters. In the contribution Dynamic Secondary Ion Mass Spectroscopy (DSIMS) is presented to reveal depth profiles of ultrathin films (< 5 nm) and their multilayers. The results on the depth profiling of Mo/Si multilayers prepared by magnetron sputtering are given. The Mo/Si structures are generally used for x-ray mirrors and their thickness must be controlled very precisely. At our measurements the depth resolution below 0.6 nm has been achieved. Energy of the primary ion beam was limited to a few hundreds of eV to reduce ion beam induced mixing of atoms. The influence of the mixing on DSIMS depth resolution was evaluated by STRIM calculations. Depth profiles achieved under different sputtering conditions (energy of primary ions and incident angles) are shown and discussed. Depth calibration is done by High Resolution Transmission Microscopy (HRTEM) and X-ray reflection (XRR). The comparison of DSIMS and HRTEM depth profiles is also made.

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