Oxidation and wet-etching behavior of MoAlTi thin films deposited by sputtering from a rotatable MoAlTi compound target

Within the current work, MoAlTi thin films have been developed and deposited by d.c. magnetron sputtering from a cold gas sprayed MoAlTi cylindrical rotatable target, to act as a novel molybdenum-based thin film system with improved oxidation and good wet-etching behavior. Chemical composition, microstructure, oxidation behavior, wet-etching properties, and electrical resistivity of the films are compared to those of a pure Mo reference film. Deviations in the chemical composition of the films with respect to the target are attributed to differences in gas phase scattering of the individual sputtered species. The films deposited are characterized by the formation of an Mo-based body-centered cubic solid solution, resulting in an increased electrical resistivity compared to the pure Mo film. While alloying Mo films with Al and Ti decreases the wet-etching rate in a phosphoric acid-based etching solution, the oxidation behavior could be significantly improved and the metallic-reflecting surface was maintained after annealing for 1 h at 330 °C in air.