微机械应力测试结构的温度特性和应力抑制方法  

Temperature characteristics of MEMS stress-testing structure and a stress-suppressing method

作　　者：刘燕锋[1] 陈志勇[1] 张嵘[1] 

机构地区：[1]清华大学精密仪器系导航工程中心,北京100084

出　　处：《光学精密工程》2016年第6期1345-1351,共7页Optics and Precision Engineering

基　　金：总装备部预先研究资金资助项目(No.20114113013)

摘　　要：研究了典型微机械应力测试结构的温度特性及从源头上抑制热应力的方法。设计了一种可以代表微机械系统(MEMS)器件温度特性的应力测试结构,并分析了温度对其固有频率的影响机理。指出了与材料弹性模量、结构尺寸变化相比,轴向应力是影响该结构固有频率温度稳定性的主要因素,同时设计了一种可以释放热应力以及加工残余应力的应力隔离结构。考虑硅的线膨胀系数随温度变化的特性,通过建模仿真和实验测试获得了应力测试结构、应力隔离结构的轴向应力以及固有频率的温度特性。结果表明:在-50℃^+85℃,应力隔离结构将轴向热应力抑制到了应力测试结构的2个数量级以下,固有频率-温度系数由5.0×10^(-3)ppm/℃左右降到了5.0×10^(-5)ppm/℃以下。结果显示:设计的应力隔离结构具有非常良好的应力隔离效果,从源头上抑制了主要的温度影响因素引入整个微机械系统,可以应用于其它MEMS结构以获得良好的温度稳定性。The temperature characteristics of typical stress-testing microstructures were studied,and a stress-suppressing method was proposed.A stress-testing structure to represent the temperature characteristics of MEMS（Micro-electro-mechanical Systems）devices was designed and the influence mechanism of temperature on its nature frequency was analyzed.It points out that the axial thermal stress is the main factor affecting temperature stability of the nature frequency as compared with the material elastic modulus and the changes of structure size.Meanwhile,a stress-suppressing structure was designed to release the thermal stress and the machining residual stress.As the linear expansion coefficient of silicon was affected by temperature,the temperature characteristics of the axial stress and nature frequency for the stress-testing structure and stress-suppressing structure were studied by simulations and experiences.The results indicate that the axial thermal stress in stress-suppressing structure is suppressed to below two orders of that in stress-testing structure,and the frequency-temperature coefficient is reduced from about 5.0×10-3ppm/℃ to below 5.0×10-5ppm/℃ at-50℃＋85 ℃.It concludes that the stress-suppressing structure suppresses the stress effectively,and suppresses the temperature influence factors into the MEMS system at the source.Moreover,the stresssuppressing structure can be used for other MEMS systems and can offer good temperature stability.

关 键 词：微机械系统 应力测试结构 应力隔离结构 温度特性 热应力 

分 类 号：O348.3[理学—固体力学] TH703[理学—力学]