AlCuMgMn micro-tensile samples: Mechanical characterization of MEMS materials at micro-scale

Measuring mechanical properties at the micro-scale is essential to understand and fabricate reliable MEMS. In this paper we present a tensile testing system and test samples on the micro-scale. The test samples have a dog-bone like structure. They were designed to mimic fundamental and standardized macro-tensile test samples.The micro-tensile tests were used to characterize 1.7 μm thick AlCuMgMn films. This alloy was selected because it is a very promising material for use in RF-MEMS switches due to its high resistance to creep.We show that the mechanical properties of the AlCuMgMn film depend not only on the alloying components but also on the material's microstructure: grain sizes, distribution, strength and density of the precipitates, etc. We show a direct relation between the film's mechanical properties and the coherence, size and spacing of precipitates as observed by SEM and TEM in the alloy.