Single Polysilicon Nano-Wire Piezoresistors for MEMS Pressure Sensor

A polysilicon nano-wire piezoresistor pressure sensor was fabricated by means of RIE (reactive ion etching). This paper focuses the structural design and optimization of the MEMS Nano-wire piezoresistive pressure sensor to enhance the sensitivity. The polysilicon nanowire pressure sensor has 100x100nm2 cross section area and has a thickness about 10nm. The diaphragm in this work is made thinner than that of the conventional bulk silicon piezoresistive pressure sensors. The single polysilicon nano-wire piezoresistive pressure sensor was compared with the conventional bulk piezoresistive pressure sensor. Finite element method (FEM) is adopted to optimize the sensor parameters, such as the resistor location. The silicon nanowire under 340nm has a good piezoresistive effect. It was proposed that silicon nanowires has seven times the piezoresistive effect than the bulk silicon. The polysilicon nanowire is fabricated in such a way that it forms a bridge between the polysilicon diaphragm and the substrate. The fabricated polysilicon nanowire has high sensitivity of about 156 mV/V.KPa.