On-chip MEMS-based internal stress actuated structures for the mechanical testing of freestanding thin film materials

摘要

An on-chip suite of MEMS-based mechanical testing structures has been developed to extract the mechanical properties of freestanding thin films under tensile loading. The working principle relies on the use of high tensile internal stress within an actuator beam to deform a specimen beam made of another material owing to the etching of an underlying sacrificial layer. In order to control the deformation rate imposed during the etching process, the rectangular shape of actuator beam design has been recently upgraded to a tapered shape. The deformation rate is estimated from the modelling of the two extreme cases defining the upper and lower limit. The proof of concept is demonstrated experimentally from the investigation of the mechanical response of 100 nm-thick freestanding copper thin films deposited by e-beam evaporation.