Improvement of oxidation and corrosion resistance of Mo thin films by alloying with Ta

Publication date: 29 January 2016
Source:Thin Solid Films, Volume 599
Author(s): Anna M. Hofer, Gregor Mori, Alexander Fian, Jörg Winkler, Christian Mitterer
Molybdenum thin films are commonly used as electrode materials for thin film transistor liquid crystal displays. As low-temperature oxidation deteriorates their electrical resistivity, the aim of this study was to improve their oxidation resistance by alloying with tantalum. Thin films with tantalum contents ranging from 0 to 100at.% have been synthesized by magnetron co-sputtering. Beside the evaluation of microstructure and resistivity with increasing tantalum content, special emphasis is laid on formation of surface oxides during exposure to elevated temperature and humidity. The formation of a transparent tantalum oxide minimizes surface oxidation, preventing growth of intensively colored molybdenum oxide scales. Potentio-dynamic measurements further highlight the positive influence of tantalum, evidencing the development of a passive region and a drop of the corrosion current density to almost zero.