Publication: 60μm memsoi low g memes accelerometer design
Date
2012-01-01
Authors
Iberahim, Nik Mohd Amali Fikri
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Abstract
MEMS (Microelectromechanical Systems) refers to the technology integrating electrical and mechanical components with feature size 1~1000 microns. MEMS accelerometers have been successfully applied for air-bag deployment systems in automobiles. In this thesis, the design optimization of a poly-silicon surface-micromachined MEMS comb accelerometer is discussed. The device uses folded-beams. There are movable fingers from both sides of movable mass. Each movable finger has left and right fixed comb fingers surrounding it, so that a differential pairs is formed. Any acceleration along the sensitive direction will induce inertial force on movable mass and deflect the beams. Hence the differential capacitance gap will change. By measuring this differential capacitance change, the experienced acceleration can be measured. CONVENTORWARE FEM analysis simulation is used to extract the device sensitivity and resonant frequency of the device. By gradually varying the design parameters in CONVENTORWARE simulation, the relationship between the device sensitivity and various design parameters is derived. The curve of device sensitivity versus beam width, beam length and mass width are derived and they are good agreement with theoretical prediction. From analysis it is concluded that the device behavior strongly depends upon various design parameters. By adjusting design parameters, desired sensitivity can be obtained. Based on simulation results, a set of optimized design parameters for the comb accelerometer is decided.