Nanocrystalline Piezoresistive Polysilicon Film by Aluminum-Induced Crystallization for Pressure-Sensing Applications

Nanocrystalline piezoresistive polysilicon films were obtained at low temperatures by aluminum-induced crystallization (AIC). The films exhibited granular structure with good polycrystalline properties. A piezoresistive pressure sensor was fabricated on a polyimide substrate, in a Wheatstone bridge configuration comprising two passive resistors and two active piezoresistors made of polysilicon films obtained by AIC. The resistors showed linear I-V characteristics with typical resistance values between 15 and 30 kΩ . Atomic force microscopy was used in contact mode to study the response of the pressure sensor with applied pressure in the 2-19 kPa range. For the higher range of 450 kPa-2 MPa, a load-cell with a nanopositioner was utilized. The pressure-sensor sensitivity was measured to be 41.12 and 5.02 mV/MPa, respectively, for these ranges, when the Wheatstone bridge was bias at 1 V.