Contrib. Plasma Phys. 49, No. 3, 107 – 133 (2009) / DOI 10.1002/ctpp.200910016 Some Aspects of Reactive Complex Plasmas J. Berndt ∗1 , E. Kovaˇ cevi´ c 1 , I. Stefanovi´ c 2 , O. Stepanovi´ c, S. H. Hong 3 , L. Boufendi 1 , and J. Winter 2 1 GREMI Universit´ e d’Orl´ eans, Polytech’Orleans, Orleans Cedex 2, France 2 Ruhr University Bochum, Insitute for Experimental Physics II, Bochum, Germany 3 Joint Experiment Team, KSTAR Research Center, National Fusion Research Institute, Daejeon, Korea Received 31 December 2008, accepted 12 February 2009 Published online 20 April 2009 Key words Plasma, reactive, dust, nanoparticles, polymerization. PACS 52.27.Lw, 82.35.Np Reactive plasmas are nowadays widely used for technological applications. The spontaneous formation and growth of dust is a phenomenon frequently observed in such plasmas. The formation of dust particles has been observed in a great variety of different discharge types and in different kind of gases or gas mixtures. Due to the large variety of different phenomena that can be observed in reactive complex plasmas this article will address some selected (general) problems and examples that are specific for the physics and chemistry of such systems. These examples concern the formation and growth of dust particles in reactive plasmas, the mechanisms responsible for that growth processes, the spatial distribution of the dust particles within the discharge, the response of the plasma to the formation and growth of dust particles and some technological aspects. c  2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction It was Irving Langmuir, one of the pioneers of plasma physics, who in 1924 described as first a dusty plasma i.e. a plasma that contains - beside the usual electron and ion component- nano or micrometer sized solid particles. Dusty plasmas have been observed since then both in terrestrial and cosmic environments and they are nowadays of great interest for various branches of physics and technology. Dust particles have been observed in fusion plasmas [1,2], in processing plasmas used for thin film deposition [3-5] or the manufacturing of microelectronic devices [6] and in extraterrestrial environments as for example in the interstellar medium, in planetary rings or in the outflow of red giant stars [7]. The formation and growth of dust particles within the plasma is the specific characteristic of reactive complex plasmas and is regarded here as definition of such plasmas. The formation of particles in reactive gases has been observed in plasmas containing different kinds of gases or gas mixtures. Probably the best characterized systems – with respect to the formation of particles- are discharges operated in silane (SiH 4 , see e.g. the examples in [8] and in fluorocarbons such as CF 4 or C 2 F 6 (e.g. [8-10]). There is a significant number of publications dealing with polymerisation processes in such kind of plasmas. The investigations on particle formation in these gases were highly motivated by their technological importance: fluorocarbon plasmas are an important tool for the etching of microstructures while discharge operated in silane are for example used for the production of solar cells. Another class of gases used for the production of particles are hydrocarbons such as C 2 H 2 or CH 4 . Reports on powder formation in hydrocarbon plasmas together with proposed models of nucleation [11-13] have already been made in the seventies. Although lately published articles [14-19] offer some more insight in the mechanisms responsible for the formation of particles the chemical picture of dust formation in hydrocarbon plasmas is still not clear. The examples mentioned so far have one characteristic in common: the precursor materials (SiH 4 , CF 4 , C 2 H 2 ) are introduced into the plasma chamber in a gaseous form. However the formation of particles has been observed also in processes based on sputtering and reactive ion etching. In these cases “atoms -or molecules- sputtered or etched from the electrode materials are the primary source of nucleation, even if the reactive gas ∗ Corresponding author: e-mail: johannes.berndt@univ-orleans.fr c  2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim