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| Sensitivity Model of Micro-machined Accelerometers Based on the Deviation of Comb Finger Gaps |
| DAI Qiang,YU Qi,QIAN Ke-qiang,ZHOU Wei |
| University of Electronic Science and Technology of China, State key laboratory of electronic thin films and integrated devices, Chengdu, Sichuan 610054, China |
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Abstract To cope with sensitivity deviation of capacitive micro-accelerometers brought by micro-machined process error in comb finger gaps, a sensitivity model is proposed based on probability theory and close loop capacitive micro-accelerometer mechanism. It is indicated that, by the model, when the accelerometers gaps dimensions are from 3.7 to 4.6 μm due to micro-machined process and meanwhile, effective voltages on the fixed electrodes are 2.3V, 5.1V and 8.3V respectively, sensitivities of the accelerometers will be in 120~195 mV/gn, 55~85 mV/gn and 32~51 mV/gn. Furthermore, a batch of bulk silicon accelerometers are tested. With the same effective voltages, the sensitivity test results are in 119.3~179.9 mV/gn,53.8~81.1 mV/gn and 33.0~49.8 mV/gn. Hence, the model and test results are relatively close to each other. Through the model, the relationship between sensitivity and comb finger gap process error has been revealed, which might hopefully serve as a reference for micro-accelerometer design and optimizing of the process.
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2011, Vol. 32 
