Thermal Characterization of Hard Decorative Thin Films Francisco Macedo, * Filipe Vaz, Ana C. Fernandes, Luı ´s Rebouta, Sandra Carvalho, Klaus H. Junge, Bruno K. Bein Introduction The search for new materials with a technological appli- cation potential can only be successful if the materials are fully characterized in terms of their structural and physical properties, including the thermal properties. Despite their importance, e.g., in hard coatings on cutting tools, the thermal properties of thin films are usually not known, probably due to the complexity of such systems and due to the lack of options concerning the measurement techni- ques suitable for such systems. On the one hand, the relevance of the thermal para- meters of such systems relies on their functional efficiency, e.g., as protective coatings on cutting tools, and on the other hand the relevance of the thermal properties relies on the possible correlations with the structural and mechanical properties of the thin films, e.g., the surface roughness, and with the film deposition conditions, e.g., the bias voltage and the gas flow rate. [1] When dealing with hard decorative thin films where the quality of the film surface is a critical subject, knowledge about the thermal properties can be an important tool to control the structural-physical parameters and to improve the whole production process. Two sets of samples, both produced by DC reactive magnetron sputtering, namely (TiSi)N and TiC x O y thin films have been studied. For the thermal measurements modulated infrared (IR) radiometry has been used, a non-contact and non-destructive technique based on thermal wave generation by intensity-modulated laser beam heating and detection of the periodic IR emission using an MCT detector and a Lock-in amplifier. The measured data have been interpreted using the so called Extremum method. [2,3] The structural/morphological characterization has been carried out using techniques such as X-ray diffraction (XRD) and atomic force microscopy (AFM). Full Paper (TiSi)N and TiCO thin films deposited by DC reactive magnetron sputtering on steel are analyzed here with regard to their thermal properties by means of modulated IR radiometry, a measurement method especially suited to analyze thin films and coatings. By varying the modulation frequency of intensity-modulated laser beam heating, this method allows to control the thermal waves’ penetration depth, thus controlling the depth profile of the thermal properties beneath the sample surface. At high modulation frequencies, corresponding to small penetration depths, surface roughness effects are sensed, and at low modulation frequencies, corresponding to large penetration depths, the transition between film and substrate is sensed. The measured thermal parameters are compared with structural/morpho- logical data obtained by techniques such as XRD and AFM. Several systematic correlations have been found between deposition conditions, structural-physical features, and surface roughness, on the one hand, and the thermal parameters on the other hand. F. Macedo Physics Department, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal E-mail: fmacedo@uminho.pt A. C. Fernandes, F. Vaz, L. Rebouta, S. Carvalho Physics Department, University of Minho, Campus Azure´m, 4800-058 Guimara˜es, Portugal K. H. Junge, B. K. Bein Experimental Physics III, Solid State Spectroscopy, Ruhr-University, D-44780 Bochum, Germany S190 Plasma Process. Polym. 2007, 4, S190–S194 ß 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/ppap.200730609