A new concept of micromachines has been developed for measuring the
mechanical properties of thin metallic films. The actuator is a beam undergoing
large internal stresses built up during the deposition process. Al thin films
are deposited partly on the actuator beam and on the substrate. By etching the
structure, the actuator contracts and pulls the Al film. Full stress strain
curves can be generated by designing a set of micromachines with various
actuator lengths. In the present study, the displacements have been measured by
scanning electronic microscopy. The stress is derived from simple continuum
mechanics relationships. The tensile properties of Al films of various
thicknesses have been tested. A marked increase of the strength with decreasing
film thickness is observed.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
