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Design, Fabrication and Micromachining Error Evaluation for a Surface-Micromachined Polysilicon Capacitice Accelerometer

표면미세가공기술을 이용한 수평감지방식의 정전용량형 다결정 실리콘 가속도계의 설계, 제작 및 가공 오차 영향 분석

  • Published : 2001.03.01

Abstract

We investigate a surface-micromachined capacitive accelerometer with the grid-type electrodes surrounded by a perforated proof-mass frame. An electromechanical analysis of the microaccelerometer has been performed to obtain analytical formulae for natural frequency and output sensitivity response estimation. A set of prototype devices has been designed and fabricated based on a 4-mask surface-micromachining process. The resonant frequency of 5.8$\pm$0.17kHz and the detection sensitivity of 0.28$\pm$0.03mV/g have been measured from the fabricated devices. The parasitic capacitance of the detection circuit with a charge amplifier has been measured as 3.34$\pm$1.16pF. From the uncertainty analysis, we find that the major uncertainty in the natural frequency of the accelerometer comes from the micromachining error in the beam width patterning process. The major source of the sensitivity uncertainty includes uncertainty of the parasitic capacitance, the inter-electrode gap and the resonant frequency, contributing to the overall sensitivity uncertainty in the portions of 75%, 14% and 11%, respectively.

Keywords

Microaccelerometer;Grid Electrode;Capacitive Detection;Perforated Proof-Mass;Uncertainty Analysis

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