The results of studies on the deposition of thin films of the ternary Al–Cu–Fe alloy by magnetron sputtering are presented. The influence of process parameters such as sputtering power, working gas pressure and substrate temperature on the composition, structure and properties of the resulting films is studied. The films are characterized by X-ray diffraction, atomic force microscopy and energy-dispersive spectroscopy.
Al–Cu–Fe-based alloys attract attention due to their unique physical and chemical properties, in particular, high hardness, corrosion resistance and the presence of quasi-crystalline phases. Thin films of these alloys are used as protective coatings, barrier layers and microelectronic elements.
In a triode system, multilayer thin Al/Cu/Fe films with different layer alternations were created by sputtering. To obtain a homogeneous Al62Cu25Fe13 film, the samples were heat-treated in an inert gas environment at temperatures up to 600 °C after the sputtering process. The required composition was achieved by accurately selecting the ratio of the thicknesses of the initial layers and the optimal annealing temperature.
AES depth profiling was used to control diffusion phenomena inside the film. X-ray structural analysis revealed the presence of binary AlCu3 and ternary β-AlCuFe phases, the formation of which depended on the annealing temperature. The development of these phases correlated with an increase in both the microhardness and electrical resistivity of the material.
Deposition of thin Al–Cu–Fe films was carried out by magnetron sputtering on substrates of single-crystal silicon and quartz glass. The target was an Al–Cu–Fe alloy of stoichiometric composition. The following parameters were varied: sputtering power (50–150 W), argon pressure (0.1–1 Pa), and substrate temperature (room temperature – 400 °C). The composition of the films was determined by energy-dispersive spectroscopy. The structure and morphology of the surface were studied by X-ray diffraction and atomic force microscopy.
Elemental composition analysis showed that the composition of the films is close to that of the target, but there is a slight deviation depending on the deposition parameters. X-ray studies revealed the presence of crystalline phases of Al, Cu and Fe, as well as intermetallic compounds. Increasing the substrate temperature improves the crystallinity of the films. Atomic force microscopy showed that the films have a smooth surface with a granular structure.
The magnetron sputtering method is an effective way to produce thin Al–Cu–Fe films with controlled composition and structure.
Author: Miha Čekada, Peter Panjan, Dalija Jurić, Janez Dolinšek, Anton Zalar
Institute: Jozsef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia, University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 19, SI-1000 Ljubljana, Slovenia