Quartz Vibrating Beam Accelerometer Technology

An new structure Quartz Vibrating Beam Accelerometer(QVBA) is described in detail in this paper. The QVBA is a monolithic quartz single beam structure obtained by a simple chemical etching process. This structure has been optimized to achieve an outstanding insulation of the active part composed of a proof mass, a vibrating beam and two articulations. The insulation with respect to the mounting areas is provided by a flexible frame. The monolithic structure is small and exquisite well suited to fabricating, mounting and miniaturization. The MEMS technology, used for the QVBa, well suited to low cost, high volume manufacturing. Therefore, it avoid processing complexity, mounting difficulty and low yield in the conventional doubled beams structure QVBA.The design theory of QVBA are introduced in this paper, include: piezoelectric effect of quartz crystal, stress- frequency effect of quartz crystal , stress- frequency effect sensitivity and it's temperature coefficient of force sensitivity, and so on. The static mathematic model and testing methods of QVBA are also introduced. It was analyzed and simulated in the structure design stage, using finite element method(FEM), including: modal analysis, dynamic response analysis, stress analysis, piezoelectric analysis. FEM analysis validated accelerometer resonance frequency, dynamic response, allowable stress and correct electrode design. The QVBA key structure parameters are also optimized by using finite element method, find suitable structure parameters finally.The QVBA key micro-machined technology are also developed in this paper, such as: single step double sides multilayer photolithographic process, quartz crystal anisotropic etching process. Thanks to the key process achieved and success use, the advantages of the new structure QVBA, such as: simple structure, well suited to high volume manufacturing , are exhibited perfectly.The key micro-machined technology developed in this project attain domestic leading level.Test results giving in the end of the paper show this new structure can well meet the anticipative performance i.e. measure range: ±50g, resolution: ≤ 1 × 10^-3g, scale factor error: ≤300ppm.