*Thomas Schütte¹, Peter Neiß¹, Jan-Peter Urbach¹, Holger Gerdes², Ralf Bandorf², Günter Bräuer^2
1PLASUS GmbH, Mering, Germany; ²Fraunhofer Institute for Surface Engineering and Thin Films, Braunschweig, Germany
Active control of plasma processes in production is still been avoided in industrial plasma processes despite major progress in hardware, software, and data evaluation of commonly known control techniques. Optical emission spectroscopy is well known for decades to monitor and control plasma processes but it is still “unwanted” in production lines. However, plasma processes are becoming more complex, e.g. like HIPIMS and highly ionized plasmas, and production processes are facing more demanding requirements towards production quality, production yield, and cost efficiency. At the same time, control techniques such as spectroscopic plasma monitoring have been improved considerably in the last years with respect to reliability, maintenance, and operation and are ready to be used in production lines meeting the challenges of recent production processes. The recent achievements of the plasma monitoring technique are presented for reactive HIPIMS processes demonstrating the simultaneous control of reactive gas flow and ionization degree not only for small cathodes but also for large area coatings with sectional balancing of the reactive gas flow. For all non-reactive highly ionized applications the degree of ionization can be pinned by the peak current and controlled by spectroscopic plasma monitoring. The corresponding algorithms are realized in a single control system with industrial interface for full integration in the overall production control system. Examples of HIPIMS processes for TiO₂, SiN, and DLC applications addressing long-term stability and target erosion are presented.