Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)

O 28.24: Poster

Mittwoch, 10. März 2004, 16:00–19:00, Bereich C

High temperature stable silicide contacts on the nanometer scale — •G. Gardinowski, C. Tegenkamp, T. Block, S. Vagt, V. Zielasek, and H. Pfnür — Institut für Festkörperphysik, Universität Hannover, Appelstrasse 2, 30167 Hannover

In order to characterize nanostructure electrically contacts are essential to build a bridge between the macrospic and the mesoscopic world. High temperature experiments with nanostructures on silicon substrates are particularly interesting, but require contacts which can withstand temperatures up to 1100C without changes in their chemical composition and without interdiffusion at the contact area of the silicide and the silicon. Using electron beam lithography different silicide contacts on both Si(111) and Si(100) surfaces have been fabricated and tested. With regard to the specific formation temperatures for silicides, mainly Mo, Ta and Ti have been tested. All three silicides are stable up to at least 800C. The metallic character of the silicides was tested by masurements of the conductivity. However, for higher temperatures the decomposition of MoSi2 and TaSi2 sets in leaving behind rough contact areas. Only the TiSi2 silicide remains intact, as checked by µ–Auger spectroscopy. Furthermore, after optimization of the lithography parameters, TiSi2 contact pads with separation lengths of 200 nm were fabricated successfully, i.e. after removing the native oxide from the silicon surface (with pads) by a high temperature annealing step, perfect silicon was found in between the contacts as seen by STM/SEM. The edges of the contacts are rather sharp and well–defined. The transition area was determined to be around 1nm.

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