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5 November 2018 Thermal stress of MOEMS accelerometers based on grating interferometric cavity
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Abstract
MOEMS accelerometers bring together the advantages of both optical measurement and MEMS technique. It has higher resolution than traditional accelerometers and can be widely implemented in more application fields. Packaging is an important step for MOEMS accelerometers in their fabrication process. It can maintain the high parallelism of the upper surface of the proof mass and the grating, so that it helps to improve the temperature stability of accelerometers. In addition, it can reduce the effect of the external temperature on the sensitive structures, thereby reducing the changes of the zero drift and scale factor by temperature. Since the accelerometers measures the acceleration which involves the stress and strain of the springs, the thermal stress introduced during the packaging process will have significant side impacts on the device performance and life, etc. In this paper, we establish a finite element method (FEM) model of the MOEMS accelerometer which contains package and sensitive structure based on grating interferometry cavity. The FEM model considers the thermal coupling of sensitive structure and adhesive, adhesive and package substrate. Based on it, the influence of the thermal stress of the material of the adhesive and the substrate are studied. The results show that a good match between the coefficient of the thermal expansion (CTE) of the substrate and sensitive structure material and a reduced elastic modulus as well as the increase of thickness of the adhesive can effectively diminish the thermal stress. Besides, well designed packaging can help to reduce the zero drift and scale factor drift to minimum.
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Weidong Fang, Qianbo Lu, Jian Bai, Dandan Han, and Peiwen Chen "Thermal stress of MOEMS accelerometers based on grating interferometric cavity", Proc. SPIE 10815, Optical Design and Testing VIII, 108151H (5 November 2018); https://doi.org/10.1117/12.2502273
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