【作者】 刘俊作；

【导师】 许焕卫； 黄洪钟；

【作者基本信息】 电子科技大学 ， 工程硕士（专业学位）， 2022， 硕士

【摘要】 微电子机械系统(MEMS)是将微敏感器、执行器以及相关的控制电路集成到一起的微型电子机械系统。随着MEMS的迅猛发展,MEMS的性能不断提升,其可靠性也越来越受到重视。MEMS器件种类繁多,其结构复杂多样,工作环境极端恶劣,存在着气密性退化、疲劳、腐蚀等问题,这为其可靠性研究带来了很大挑战,制约了MEMS的发展。鉴于此,本文以典型MEMS产品—MEMS电容式加速度传感器作为研究对象,研究MEMS加速度传感器性能退化与可靠性分析方法,为提高MEMS可靠性、推动MEMS技术发展提供理论支撑。本文主要包括以下研究内容:(1)介绍MEMS加速度传感器的结构及工作原理;分析MEMS加速度传感器的失效模式及失效机理,确定敏感结构裂纹扩展以及封装气密性退化为本文主要针对的MEMS加速度传感器失效模式;阐述性能退化研究的相关方法及理论,为MEMS加速度传感器性能退化研究提供理论基础。(2)基于威布尔型退化量分布模型和有限元分析方法对MEMS加速度传感器封装气密性退化进行研究。通过分析MEMS加速度传感器的结构及封装原理,将腔体内水汽含量作为MEMS气密性的性能退化指标;采用COMSOL软件,建立MEMS加速度传感器的气密性退化仿真模型;基于威布尔型退化量分布模型进行气密性退化研究,建立传感器气密性退化模型,并进一步对其进行可靠性分析,计算得到其可靠度。(3)基于Gamma随机过程和有限元分析方法对MEMS加速度传感器敏感结构裂纹扩展进行研究。分析硅微薄膜在静态载荷以及动态载荷下MEMS加速度传感器敏感结构的疲劳裂纹扩展机理,确定疲劳裂纹扩展所导致的MEMS加速度传感器的两种主要失效模式:折叠梁裂纹扩展断裂和测量误差过大;将硅微结构裂纹扩展理论引入到MEMS加速度传感器敏感结构裂纹扩展中,并结合COMSOL软件建立疲劳裂纹扩展仿真模型以及测量误差仿真模型;根据仿真得到的裂纹扩展以及测量误差数据的特点,采用Gamma过程分别对两种失效模式进行性能退化建模,进一步推导MEMS加速度传感器可靠度。(4)基于Copula理论对MEMS加速度传感器进行多失效模式相关下的可靠性分析。采用二元Clayton Copula函数,对气密性退化失效、硅微折叠梁裂纹扩展断裂以及测量误差过大三种失效模式两两之间相关下的MEMS加速度传感器可靠性进行分析;进一步采用三元Clayton Copula函数,对这三种失效模式相关下的MEMS加速度传感器的可靠性进行分析。更多还原

【Abstract】 Micro-electro-mechanical system(MEMS)that integrates micro sensors,actuators and related control circuits.With the rapid development of MEMS,the performance of MEMS has been continuously improved,and its reliability has been paid more and more attention.There are many kinds of MEMS devices,their structures are complex and diverse,the working environment is extremely bad,and there are problems such as air tightness degradation,fatigue,corrosion and so on,which bring great challenges to the reliability research and restrict the development of MEMS.In view of this,this paper takes the typical MEMS product-MEMS capacitive acceleration sensor as the research object to study the performance degradation and reliability analysis method of MEMS acceleration sensor,so as to provide theoretical support for improving the reliability of MEMS and promoting the development of MEMS technology.This paper mainly includes the following research contents:(1)The structure and working principle of MEMS acceleration sensor are introduced;The failure mode and failure mechanism of MEMS acceleration sensor are analyzed,and the crack propagation of sensitive structure and the degradation of package air tightness are determined as the failure modes of MEMS acceleration sensor in this paper;The related methods and theories of performance degradation research are described to provide a theoretical basis for the performance degradation research of MEMS acceleration sensors.(2)Based on Weibull degradation distribution model and finite element analysis method,the gas tightness degradation of MEMS acceleration sensor packaging was studied.By analyzing the structure and packaging principle of MEMS acceleration sensor,the moisture content in the cavity is taken as the performance degradation index of MEMS air tightness;Using COMSOL software,the simulation model of air tightness degradation of MEMS acceleration sensor is established;Based on the Weibull type degradation quantity distribution model,the gas tightness degradation model of the sensor is established,and its reliability is calculated.(3)Based on gamma random process and finite element analysis method,the crack propagation of MEMS accelerometer sensitive structure is studied.The fatigue crack propagation mechanism of MEMS accelerometer sensitive structure under static and dynamic load is analyzed,and two main failure modes of MEMS accelerometer caused by fatigue crack propagation are determined: crack propagation fracture of folded beam and excessive measurement error;The crack propagation theory of silicon microstructure is introduced into the crack propagation of MEMS acceleration sensor sensitive structure,and the crack propagation model is established.The fatigue crack propagation simulation model and measurement error simulation model are established by COMSOL software;According to the characteristics of crack propagation and measurement error data obtained from simulation,the performance degradation models of the two failure modes are respectively modeled by gamma process,and the reliability of MEMS acceleration sensor is further derived.(4)Based on Copula theory,the reliability of MEMS acceleration sensor under multi failure mode correlation is analyzed.Using the binary Clayton copula function,the reliability of MEMS acceleration sensor is analyzed under the correlation of three failure modes: air tightness degradation failure,crack propagation and fracture of silicon micro folded beam and excessive measurement error;Furthermore,the reliability of MEMS acceleration sensors under the correlation of these three failure modes is analyzed by using the ternary Clayton copula function.更多还原