  We present mechanical measurements performed at low temperatures on
cantilever-based microelectro-mechanicalstructures(MEMS) coated with a metallic
layer. Two very different coatings are presented in order to illustrate the
capabilities of the present approach, namely (soft) aluminum and (hard) niobium
oxide. The temperature is used as a control parameter to access materials
properties. We benefit from low temperature techniques to extract a
phase-resolved measurement of the first mechanical resonance mode in cryogenic
vacuum. By repeating the experiment on the same samples, after multiple
metallic depositions, we can determine accurately the contribution of the
coating layers to the mechanical properties in terms of surface stress,
additional mass, additional elasticity and damping. Analytic theoretical
expressions are derived and used to fit the data. Taking advantage of the
extremely broad dynamic range provided by the technique, we can measure the
anelasticity of the thin metallic film. The key parameters describing the
metals' dynamics are analyzed in an original way in order to provide new
experimental grounds for future theoretical modelings of the underlying
mechanisms.
