Metal-silicon reactions were intensively studied for its direct application in semiconductor industry. Cobalt is one of the key elements in MOSFET structures. Deposited cobalt atoms form near the surface interstitial sites at sub-monolayer coverage. Further cobalt deposition leads to the formation of cobalt silicide surface clusters and islands. The silicide growth is reduced when the film thickness reaches about 1.5 nm [1] . From this point on, island structures and layers of pure cobalt are formed which becomes important for fabrication of magnetic layered structures and nanostructures. It is obvious that the type and quality of substrates, deposition temperature, post deposition annealing and the ambient atmosphere (oxygen, hydrogen,...) play an important role in the growth mechanism.
In this contribution a study of the cobalt growth on silicon substrates under different experimental conditions by in-situ Low Energy Ion Scattering (LEIS) is presented. Our spectrometer is equipped with a time-of-flight (TOF) energy analyzer and benefits from its surface sensitivity as well as from its ability to analyze near-subsurface atomic layers [2]. The capability of TOF-LEIS to monitor the early stages of cobalt growth ranging from sub-monolayer up to monolayer coverage is demonstrated. The results from the TOF-LEIS experiments were supported by other techniques used in our lab, mainly XPS, LEED, SIMS and ex-situ AFM.
[1] P.A. Bennett, D.G. Cahill, M. Copel, Phys. Rev. Lett. 73/3, p. 452-455 (1994).
[2] M. Kolibal, S. Prusa, M. Plojhar, P. Babor, T. Sikola, Nucl. Instrum. Methods Phys. Res., Sect. B 249, p. 318-321 (2006).
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