Suspended Submicron Silicon-Beam for High Sensitivity Piezoresistive Sensing

AbstractThis paper presents a submicron suspended piezoresistive silicon-beam structure as a basic sensing element to replace the conventional piezoresistors, so to improve the detection sensitivity. The alternative element benefits from the increase of the induced stress, which is locally concentrated on the suspended submicron beam. This approach allows the enhancement of sensitivity without modifying the parameters in the mechanical design. A modified deep reactive- ion etching process is developed to create both the suspended silicon-beam and the main mechanical structure in a single etching sequence. With the new element, sensitivity up to 52.5V/N is obtained, corresponding to a 120% improvement compared to an equivalent structure with conventional piezoresistors