Nanoscale deformation measurements for reliability analysis of sensors

With ongoing miniaturization from micro electronic mechanical systems (MEMS) towards nano electronic mechanical systems (NEMS), there is a need for new reliability concepts making use of meso-type (micro to nano) or fully nanomechanical approaches. For the development of theoretical descriptions and their numerical implementation on the basis of simulation tools experimental verification will be of major interest. Therefore, there is a need for measurement techniques with capabilities of determination and evaluation of strain fields with very local (nanoscale)resolution. Following this challenge the authors developed the nanoDAC method (nano Deformation Analysis by Correlation) which enables the extraction of nanoscale displacement fields from scanning probe microscopy (SPM) images. Components of interest are thermomechanically loaded under the SPM and topography scans of the critical areas are taken at specific load states. The obtained images are analyzed by digital image correlation resulting into full-field displacement and strain fields. Due to the application of SPM equipment deformations in the micro-, nanometer range can be easily detected. The method can be performed on bulk materials, thin films and on devices i.e microelectronic components, sensors or MEMS/NEMS. Furthermore, the characterization and evaluation of micro- and nanocracks or defects in bulk materials, thin layers and at material interfaces can be carried out. In combination with finite element simulations the application of the described experimental method to sensor elements is a promising approach for reliability analysis of newly designed sensor architectures.