Jan-Peter Urbach, Thomas Schütte, Peter Neiß, PLASUS GmbH, Mering, Germany
Plasma processing is an indispensable tool to modify the surface in order to tailor its optical, chemical or physical properties. Ever increasing demands for better specifications and lower scrap rates drive the demand for efficient process control systems. This requires short control loops, and in turn measurement systems that gather process conditions as well as product properties as close as possible to the manufacturing process.
Spectroscopic plasma process monitoring is a standard measurement technique to acquire data from the actual coating process. In addition broadband photometric measurements of the coated surface can reveal important properties of produced layer such as film thickness or color values. Furthermore the chemical film composition as well as the surface roughness will influence the optical properties of the surface and can be detected in the photometric signal.
In this talk examples of combined in-situ and in-line plasma monitoring and photometric measurements in demanding coating processes are presented, including applications in tribological, photovoltaic and architectural glass coating. The impact of process variations as detected by plasma monitoring systems on the film properties is discussed, which allows a deeper insight of the relationship between plasma condition and film composition. By combining information from both measurement techniques in a single system in real-time the accuracy of the process monitoring and in turn the product quality are improved.