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
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.
DAI Qiang,YU Qi,QIAN Ke-qiang, et al. Sensitivity Model of Micro-machined Accelerometers Based on the Deviation of Comb Finger Gaps[J]. Acta Metrologica Sinica, 2011, 32(2): 101-105.
［1］于梅,马明德. 振动标准套组灵敏度测量的不确定度评估［J］. 计量学报,2007,28（4）:349-353.
［2］金振林,张晓辉, 高峰. Stewart型指尖力传感器结构尺寸对其灵敏度的影响研究［J］.计量学报,2004,25（3）:262-265.
［3］Zhu X, Greve, D W, Fedder G. K. Characterization of silicon isotropic etch by inductively coupled plasma etch in post-CMOS processing［C］// Proceedings of the IEEE Micro Electro Mechanical Systems (MEMS). Miyazaki, Japan, 2000: 568-573.
［4］Chen H, Wang Q. Trench profile angle beveling ［J］. Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, 2008, 26(5):1172-1177.
［5］Rudawski N G, Jones K S, Gwilliam R. Dopant-stress synergy in Si solid-phase epitaxy ［J］. Applied Physics Letters, 2008, 92( 23): 232110-1~232110-3.
［6］张鉴. MEMS加工中电感耦合等离子体(ICP)刻蚀硅片的模型与模拟［D］. 博士学位论文,东南大学,2006.
［7］Dong L X, Che L F, Sun L L, et al. Effects of non-parallel combs on reliable operation conditions of capacitive inertial sensor for step and shock signals［J］. Sensors and Actuators, A: Physical, 2005, 121(2): 395-404.
［8］Dai Q, Yu Q, Rao Q, et al. pulse and step signal response models of micro-accelerometers based on the comb gaps deviation［J］. Chinese Journal of Semiconductors. 2008,29 (7):1391-1395.
［9］Tang X C, Zhang Y F, Chen W P, et al. A system-level simulation of force-balance MEMS accelerometers by VHDL-AMS［C］//SPIE, 2008: 7130.
［10］Grigorie T L. The Matlab/Simulink modeling and numerical simulation of an analogue capacitive micro-accelerometer. Part 1: Closed loop［C］//MEMSTECH. Polyana. 2008:105-114.
［11］Bao M H, Huang, Y P, Yang H, et al. Reliable operation conditions of capacitive inertial sensor for step and shock signals［J］. Sensors and Actuators, A: Physical, 2004,114(1): 41-48.
2011, Vol. 32 
