Sensitivity enhancement of piezoresistive micro acceleration sensors with Nanometer Stress Concentration Regions on sensing elements

This paper presents a novel approach for considerably enhancing the sensitivity of piezoresistive microcantilever-type acceleration sensors. The design, fabrication and characterization of an ultra miniature single crystal micro acceleration sensor with Nanometer Stress Concentration Region (NSCR) on piezoresistors utilizing bulk micromachining techniques and Focus Iron Beam tool (FIB) have been discussed. Finite element simulations indicate an increase in sensitivity compared to a conventional microcantilever beam with the same thickness by a factor of 8.6. Devices have been fabricated and initial characterization has been performed. The new design shows an increase in the relative resistance change compared to a microcantilever with the same thickness and conventional piezoresistor design.