Jan-Peter Urbach, Thomas Schütte, Hokuto Kikuchi, PLASUS GmbH, Mering, Germany
Decorative coatings represent a major area of application for thin film deposition technologies. In contrast to other areas, where the key performance parameters are of technical nature, the esthetic properties of the coated surface are most important and among those most of the time color is paramount. The goal is to reproduce the color impression that the designer of a product had intended.
To bridge the gap between individual color perception and objective surface properties, color values such as the CIA LAB system are often used. Ex-situ color measurement systems are readily available. However, such downstream measurement only allows for an indirect feedback loop for controlling and correcting the production process. Color deviations caused e.g. by unintentional process fluctuations are detected too late and cannot be corrected.
This situation can be overcome by an in vacuum color monitoring technology, that is capable of measuring the color values of a growing film in-situ and continuously. Such technology allows to detect and assess the impact of process deviations on the surface color in real time. Furthermore, it allows a precise endpoint detection based on the current coating status. This technology was implemented in the EMICON product line. The EMICON LC can either be operated as a stand-alone system or it can be integrated as an add-on module to an existing EMICON SA system for plasma monitoring.
This presentation illustrates the performance of the EMICON LC system in different coating applications with varying surface characteristics and discuss the benefits and the challenges of this monitoring technology also in conjunction with complementary in-situ measurement techniques like plasma emission monitoring. Application examples from magnetron sputtering, PECVD and ALD are discussed.