Oxidation of Sputtered Thin Films of Molybdenum Alloys at Ambient Conditions

*, C. Mitterer*, G. Mori**, J. Winkler***, N. Reinfried*** and W. Knabl*** * Department of Physical Metallurgy and Materials Testing, Montanuniversitat, Leoben, Austria ** Department of General, Analytical and Physical Chemistry, Montanuniversitat, Leoben, Austria *** PLANSEE Metall GmbH, Reutte, Austria Room temperature oxidation of Mo in the presence of humidity may deteriorate its properties in thin film applications like thin film transistor liquid crystal displays or photovoltaic cells. To improve their oxidation resistance, Mo films of 200 nm thickness, alloyed with the elements Ti, Cr, Ni, Nb, Ta, or W, respectively, have been grown by magnetron co-sputtering from Mo mosaic targets with the respective alloying element inserts. All coatings show single-phase solid solutions. The respective alloying content is determined by the number of target inserts, their respective sputter yield and the scattering probability during transport from the target to the substrate, and could be confirmed by SRIM calculations. Electrical resistivity values are comparable to those of unalloyed Mo. Corrosion properties have been determined in 85 % humidity at 85°C by use of exposure tests in a climatic chamber. Potentiodynamic and electrochemical impedance spectroscopy were additionally done in 0.9 % NaCl aqueous solution at room temperature. Cr was identified as the alloying element resulting in the highest corrosion resistance due to formation of a passive layer.