Design of Piezoresistive MEMS Accelerometer with Optimized Device Dimension

Abstract

The advent of microfabrication has given a great impetus to MEMS inertial sensors particularly MEMS automobile sensors. In developing Microsystem technology, FEA has been acknowledged as the most cost and time effective alternative to building a prototype for simulation. Present work focuses on developing mathematical model in order to formulate a design procedure to determine the influence of geometric attributes of a four and an eight beam cross bridged accelerometer for automotive applications pertaining to lower inertial loads ( 2g). The configuration is so chosen to minimize cross-axis sensitivity and temperature variation. The proposed mathematical model takes both mechanical and electrical aspects into consideration. Both accelerometers are doped with p-type (boron diffused) silicon at two ends of its flexures. An optimization based on genetic algorithm has been carried out to determine the best possible geometric configuration while satisfying the specification of automotive inertia sensors. A solid model based on optimized dimensions has been simulated using ANSYS to determine stress, deformation, sensitivity for both configurations followed by validation with analytical results. The two configurations have been compared on the basis of output behaviour and performance parameters, and the obtained results are described in detail.