Finite elements study of high mechanical stress in nanostructures for innovative NEMS sensors

Mechanical stress is increasingly applied in micro-electronics. For instance, strained silicon technology is widely used to improve carrier mobility and therefore driver current for advanced MOS transistors. For micro-electromechanical systems, piezoresistive effects are universally employed in pressure sensors. In this paper we present an original method for studying mechanical stress in nano-devices placed on ultra-thin membranes, which has several advantages compared with the conventional four-point-bending method. Using this new architecture, we investigate the innovative NEMS pressure sensor properties in static and dynamic modes. We study the optimal orientation and position of a nanowire on the membrane. We show that a large improvement in pressure measurement sensitivity can be obtained by adopting tunnel junction technology. We also investigate the dynamic multi-bends of the nanostructure in its dynamic deformation modes and calculate the tunnel current which passes through the multi tunnel junctions by the transport matrix method. Finally, our work helps to understand the electrical and mechanical properties of the nanostructure under the influence of large mechanical stress and to design innovative NEMS pressure sensors.