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Changes in the elastic properties of silver/nickel superlattices due to thermal treatments were discussed. This involves the utilization of a Brillouin light-scattering experiment which conducted at-temperature experiments and measurements at reference temperature after thermal cycles in four guided acoustic modes. The correspondence between elastic constant variations and structural changes determined by x-ray difraction was demonstrated.

The Brillouin light scattering technique was used to study the elastic properties and interface effects of Ag/Ni superlattices. The two effective elastic constants c11 and c44 were determined for both free-standing and glass-supported superlattices. C44 was found to decrease by 40% as the period decreased from 19 to 1.3 nanometers while c11 proved to be period-independent. Measurements on supported specimens also revealed information on the constant c33 which exhibited a monotonic increase with period. Interface quality was also seen to improve with lowered temperature.

To clarify the underlying mechanisms that cause the preferred orientation in TiN films, we investigated the evolution with the thickness of the texture, surface morphology, and residual stress in TiN thin films deposited by dual ion beam sputtering. The films, with thickness h ranging from 50 to 300 nm, were grown on oxidized Si substrates using a primary Ar ion beam accelerated under 1.2 kV and different voltages Va of the (Ar+N2) assistance beam: 25, 50, and 150 V. The influence of temperature was also investigated by varying the substrate temperature Ts (25–300 °C) during growth or by performing a postdeposition annealing. X-ray diffraction (XRD) as well as transmission electron microscopy were used to study the microstructure and changes of texture with thickness h, while x-ray reflectivity and atomic force microscopy measurements were performed to determine the surface roughness. Residual stresses were measured by XRD and analyzed using a triaxial stress model. The crystallite group method was used for a strain determination of crystallites having different fiber axis directions, i.e., when a mixed texture exists. The surface roughness is found to increase with Va and Ts due to the resputtering effect of the film surface. XRD reveals that for a small thickness (h∼50 nm) the TiN films exhibit a strong (002) texture independent of Va. For a larger thickness (100s=300 °C, where the predominant texture remains (002). A minor (220) texture is also found, but its contribution strongly decreases with Va and Ts. The residual stresses are highly compressive, ranging from -8 to -5 GPa, depending on the deposition conditions. When a mixed texture exists, the analysis reveals that (111)-oriented grains sustain stresses that are about 20% more compressive than those sustained by (002)-oriented grains. The present results suggest that the change in the preferred orientation from (002) to (111) is not correlated with a strain energy minimization or with a systematic increase in surface morphology. Rather, kinetically driven mechanisms occurring during growth and linked to anisotropies in surface diffusivities, adatom mobilities, and collisional cascades effects are likely to control the texture development in TiN thin films produced with energetic ionic species. This interpretation is supported by in situ temperature XRD measurements. [ABSTRACT FROM AUTHOR]

TiN/TiAl(N) multilayers of various modulation wavelengths are deposited onto silicon substrates at room temperature by using ion beam sputtering. Depending on the nitrogen concentration [C.sub.N] inside TiAl layers and on the modulation wavelengths, the annealing has induced a solid-state phase transformation that has involved a complex diffusion mechanism.