跷跷板式MEMS加速度计锚点与梁优化设计  

Optimal Design of Anchor and Beam of Teeter-Totter Type MEMS Accelerometer

作　　者：任臣[1] 杨拥军[1] 陈鹏旭 Ren Chen;Yang Yongjun;Chen Pengxu(The 13^(th)Research Institute,China Electronics Technology Group Corporation,Shijiazhuang 050051,China)

机构地区：[1]中国电子科技集团公司第十三研究所,石家庄050051

出　　处：《微纳电子技术》2022年第4期348-355,共8页Micronanoelectronic Technology

摘　　要：作为敏感外界加速度的器件,微电子机械系统(MEMS)加速度计容易受到外界应力的影响。而跷跷板式加速度计采用直梁的结构形式,其温度性能、抗冲击和过载能力都较差,在梁及其连接处会因应力集中,造成加速度计结构发生形变甚至损伤。因此为了提高跷跷板式加速度计的可靠性和温度性能,对锚点和梁进行了优化设计。首先,介绍了跷跷板式MEMS加速度计的工作原理,建立了其动力学方程,利用有限元仿真分别建立了锚点与梁的模型,分析加速度计的梁以及梁的连接处这两个应力集中部位的应力。其次,设计了带应力释放结构的锚点和带应力缓冲结构的梁。仿真结果表明,加速度计的锚点设置应力释放结构后,锚点与梁的连接处由过载产生的最大应力减小了约51%,梁上以及梁和结构连接处的热应力分别减小了约37%和38%。经过优化设计后,梁对敏感方向的抗过载能力提升最明显,梁与结构连接处的最大应力由约1 915 MPa减小到了约1 547 MPa,减小了约19%。实验结果表明,经过锚点与梁的优化设计后,加速度计的梁以及梁的连接处所受应力大大减小,提高了加速度计的性能和可靠性。As a sensitive device to external acceleration, the micro-electromechanical system(MEMS) accelerometer is easily affected by the external stress. The teeter-totter type accelero-meter adopts the structure of straight beam, so its temperature performance, impact resistance and overload capacity are all poor. The structure of the accelerometer will be deformed or even damaged due to stress concentration on the beam and at connections. To improve the reliability and temperature performance of the teeter-totter type accelerometer, the design of the anchor and beam were optimized. Firstly, the working principle of the teeter-totter type MEMS accelerometer was introduced, and the dynamic equation was established. The models of the anchor and the beam were established respectively by finite element simulation to analyze the stresses of two stress concentration parts, i.e.the beam and connections of beams for the accelerometer. Secondly, the anchor with the stress release structure and the beam with the stress buffer structure were designed. The simulation results show that after the stress release structure is set at the anchor of the accelerometer, the maximum stress at the connections between the anchor and the beam caused by overload is reduced by about 51%. The thermal stresses on the beam and at the connections between the beam and the structure are reduced by about 37% and 38%, respectively. After the optimal design, the anti-overload capacity of the beam in the sensitive direction is improved most obviously, and the maximum stress at the connections between the structural beam and the structure is reduced from about 1 915 MPa to about 1 547 MPa, which is reduced by about 19%. The experiment results show that after the optimal design of the anchor and beam, the stresses of the beam and the connection of the beam are greatly reduced, and the performance and reliability of the accelerometer are improved.

关 键 词：微电子机械系统(MEMS) 跷跷板式加速度计 锚点 梁 有限元分析 

分 类 号：TH824.4[机械工程—仪器科学与技术] TH703[机械工程—精密仪器及机械]