Measurement of nanometric deformations of microsystems

The increasing trends towards miniaturization in many different application fields, have produced a dramatic progress in the development of microelectromechanical systems (MEMS) and microoptomechanical systems (MOEMS). The measurement of the deformation of such systems may be used for the calculation of strain and, along with the evaluation of applied forces, allows for obtaining stresses and consequently extraction of material parameters. This information may in turn be used for the validation of FEM models and eventually detect defects in microsystems. Since the structures themselves exhibit typical dimensions of the order of some micrometers, it is necessary to measure the deformation with accuracies in the nanometer range. At first reference test MEMS, from which we know exactly how they deform when submitted to loading, have been developed. The reference MEMS have then been measured by using different interferometric systems (digital holography, speckle interferometry, heterodyne interferometry) which are able to measure in-plane and out of plane nanometric deformations and the uncertainty of the measurement is determined according to internationally recognized guidelines.