Characterization method for mechanical properties of thin freestanding metal films for RF-MEMS

A method for the characterization of mechanical properties of freestanding thin metal film materials used in RF-MEMS is evaluated. Freestanding beam structures are manufactured from a sputtered layer of AlCu(1wt%) on top of a wafer using an industrialized RF-MEMS manufacturing process. The methods of examining microstructure and geometry are studied. It is shown that these methods are promising for extracting the desired information about the material. Simple bending experiments are carried out on micro-scale beams of varying length and thickness using an indenter device. Elastic material properties are extracted from the results, using finite element technology combined with elastic theory, removing the necessity of extensive finite element simulations. It is shown that the beam length and indenter positioning play a crucial role. The obtained results show agreement with expected values for longer beams, but no obvious relation with the film thickness is found within the experimental range addressed