Guest Experimental Physics II - Prof. von Keudell



Prof. Diederik Depla from the Department of Solid State Sciences at Ghent University (Belgium) will visit the Institute of Experimencal Physics next week. You are all cordially invited to attend to his short seminar about "Magnetron sputter deposition, the role of the ions" on Tuesday January 15th, 2013, NB5/158, at 10:00 (s.t.).

Abstract: Ions play an prominent role during reactive magnetron sputtering. Their influence can be quite explicit as for example when a substrate bias is applied during thin film growth. However, ions can also play a more hidden role. This paper aims to give an overview of the different processes in which ions play a key role.
The first, and most obvious during magnetron sputtering, is of course the sputter process as such. Although it seems straightforward to describe this, fundamental issues as the angular emission profile, compound sputter yield hampers a quantitative description of the deposition profile, and therefore the deposition rate at the substrate [1].
A similar question exists about the role of ions during the sustaining mechanism of the magnetron discharges. In recent years, substantial progress has been in the understanding of the behaviour of the electron emission yield when oxidizing the target [2]. As the latter behaviour also influences the emission of negative oxygen ions, a good understanding is needed because high energetic negative oxygen ions affect in an important way the growth of the thin film. A few examples of this behaviour will be given [3].
As the ions bombard the target, they also become implanted. For inert gas atoms, their influence is minor. However, reactive ion implantation is an important pathway in the poisoning mechanism during reactive magnetron sputtering [4]. The paper will discuss the latest trends in the modelling of this process.
Finally, ions can be used as a tool to influence the thin film growth. As they are charged species, their energy can easily be influenced by biasing the substrate. Moreover, they can also be guided towards the substrate. This approach becomes even more interesting when most of the metal species are ionized as in HIPIMS plasmas. However, when studying thin film growth, one must realize that not only the ions are important, and other species play also their role. This will be discussed in the context of the characterisation of the different particle fluxes from the plasma towards the substrate [5].

Diederik Depla

[1] Deposition of thin films by sputtering cold isostatically pressed powder targets: A case study. F. Boydens, W. Leroy, R. Persoons, D. Depla. Phys. Status Solidi A, 209: (2012), 524-530
The correlation between target surface morphology and sputter deposition rate, F. Boydens, W.P. Leroy, R. Persoons, D. Depla, paper accepted in J. Phys. D : Appl.Phys.
[2] Magnetron sputter deposition: Linking discharge voltage with target properties, D. Depla, S. Mahieu, R. De Gryse, Thin Solid Films 517 (2009) 2825–2839
[3] Modeling the flux of high energy negative ions during reactive magnetron sputtering, S. Mahieu, W. P. Leroy, K. Van Aeken, and D. Depla, J. Appl. Phys. 106 (2009) 093302
[4] Rotating cylindrical magnetron sputtering: Simulation of the reactive process, D. Depla, X. Y. Li,S. Mahieu,K. Van Aeken,W. P. Leroy, J. Haemers, R. De Gryse, A. Bogaerts, J. Appl. Phys. 107 (2010) 0113307
[5] Sputter deposited transition metal nitrides as back electrode for CIGS solar cells, S. Mahieu, W.P. Leroy, K. Van Aeken, M. Wolter, J. Colaux, S. Lucas, G. Abadias, P. Matthys, D. Depla, Solar Energy 85 (2011) 538–544