The internal stress of TiCux-alloy films on alumina substrates was measured in situ under UHV-conditions as a function of substrate temperature and stoichiometry using a cantilever beam technique.
The stress vs. thickness curves of alloy films with TiCu0.5, TiCu, TiCu2 and TiCu3 stoichiometry indicate that the film growth is amorphous at 130°C and polycrystalline at 350°C substrate temperature, which was confirmed by TEM-investigations. Furthermore TED-results of alloys deposited at 350°C imply that the TiCux-alloy-phases formed at that temperature are Ti2Cu, γ-TiCu, TiCu3 and TiCu4.
The influence of substrate temperature on the growth of TiCux-alloy films (x = 1) was investigated in more detail. At substrate temperatures below 300°C the stress vs. thickness curves indicate the formation of amorphous alloy films, again confirmed by TEM- and TED-analysis. At substrate temperatures around 300°C a strong tensile stress contribution above a mean thickness of about 20 nm indicates a change in the growth mode and thus microstructure of the alloy film. The corresponding TEM- and TED-micrographs show quasi single-crystalline films. Finally at 350°C substrate temperature the stress vs. thickness curves indicate once again a change in the film growth mode, the film structure is polycrystalline and the formation of γ-TiCu is deduced fore TED-results.
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