Fabrication and characterization of a bulk micromachined polysilicon piezo resistive accelerometer

In this work, the fabrication and characterization of a MEMS bulk micromachined piezo resistive accelerometer. For transduction, polysilicon piezo resistors are used. Polysilicon piezo resistors are preferred over SOl-based silicon piezo resistors because they are cost effective. The accelerometer is designed using FEM-based MEMSCAD tool CoventorWare®. The accelerometer sensor is realized using a hybrid approach of wet and dry bulk micro machining techniques. <100> bar corner compensation technique was used for the back side bulk micromachining of the accelerometer structure as indicated in this article. The developed process is CMOS compatible, and can be extended for CMOS-MEMS integration. Interface electronics required for the Wheatstone bridge signal readout is also presented. The developed sensor is characterized for static and dynamic performance, using nano-indenter and electrodynamic shaker, respectively. From static characterization, stiffness and natural frequency are found to be 7.25 kN/m and 6.78 kHz, respectively. From dynamic characterization, bandwidth and sensitivity are found to be 475 Hz and 10 mV/V/g, respectively