The nonlinear dynamic response of microbeam of MEMS capacitive switch under mechanical shock

The microelectromechanical system (MEMS) capacitive switch based on clamped?Cclamped microbeam has garnered significant attention due to their geometric simplicity and broad applicability, and the accurate model which describes the multiphysical effects of MEMS capacitive switch should be developed to predict the nonlinear dynamic response of clamped?Cclamped microbeam. A improved macromodel of the clamped?Cclamped microbeam-based MEMS capacitive switch is presented to investigate the nonlinear dynamic response of clamped?Cclamped microbeam of MEMS capacitive switch under different mechanical shock in this article, the macromodel provides an effective and accurate design tool for this class of MEMS devices because of taking account into some effects simultaneously including midplane stretching effect, residual stress and different mechanical shock loads. A numerical analytical method based on multimode Galerkin discretization is presented to investigate the nonlinear response of clamped?Cclamped microbeam of MEMS capacitive switch under the different mechanical shock loads. The results show that using five or more modes can be sufficient to capture the nonlinear dynamic response of clamped?Cclamped microbeam, and the microbeam experiences a mechanical shock load as a quasi-static load or a dynamic load depending on the ration between the natural periods of the structure and the period or frequency of mechanical shock load. The proposed method gives the identical results to other numerical methods in the literature. Moreover, this method is straightforward to implement and could save computation efforts while not losing accuracy.     

MEMS开关的失效模式及机理的分析

主要探讨了微电子机械系统中普遍存在的失效模式及机理,对几种没有明确对应模式的失效机理也做了介绍。最后针对一种具体的微机械开关器件,研究了它的可靠性问题,给出了相应的可靠性提高措施。该微机械开关主要受限于两种失效模式,其中结构粘附主要发生在结构释放工艺,大大降低了成品率;而金属接触电极之间的压降引起的电弧现象,则对开关的工作寿命形成了严重限制。通过对几种结构释放工艺的比较,指出SCCO2是最佳的释放措施,并比较了几种不同的金属接触电极以降低电弧效应。该微机械开关的工作寿命已由初期的106开关次数提高到了普遍高于108开关次数。     

RF inductors with suspended and copper coated thick crystalline silicon spirals for monolithic MEMS LC circuits

This letter presents a novel radio frequency (RF) inductor in a monolithic inductor-capacitor circuit developed by using micro-electromechanical systems (MEMS) fabrication technology. The inductor consists of 40-/spl mu/m-thick single crystalline silicon spiral with copper surface coating as the conductor, which is suspended on a glass substrate. The fabricated inductor exhibits a self-resonance frequency higher than 15GHz, with the quality factor more than 35 and inductance over 5nH at 11.3GHz. Simulations based on a compact equivalent circuit model with parameters extracted using a characteristic-function approach have also been carried out for the inductor, and good agreement with measurements is obtained.     

Reliability of MEMS shallow arches based actuator under the combined effect of mechanical shock and electric loads

Critical issues for the development of MEMS devices are their performance, reliability and survivability when subjected to unwanted loads, such as when dropped on a hard surface. These active forces can lead to tremendous destruction in these tiny mechanisms, such as stiction and all related short circuit problems in MEMS devices. Investigating the reliability of micro-structures under mechanical shock loads is a challenging job, driven, in part, by the large deflections that exacerbate system nonlinearities, such as those due to geometric (such as mid-plane stretching) and also the actuating nonlinear electric load. The proposed work aims to establish computationally efficient approaches that are capable of analyzing the transient dynamics of bi-stable MEMS devices, such as shallow arches, to mechanical shock and electric loadings. This investigation aims to improve the understanding of how mechanical shock loads can deteriorate the bi-stability of MEMS shallow arches. To this end, a Galerkin expansion reduced-order modeling (ROM) will be exploited. The capability of the ROM in simulating the bi-stable dynamical response of such devices to the combined effect of electrostatic force and shock load is thoroughly studied and analyzed. The ROM is utilized to explore the effect of several design parameters on the dynamic response of initially curved microbeams to shock loads: such as the shock amplitude, the shock duration, the beam initial curvature, and the DC voltage. Universal curves for the snap-through and pull-in voltages thresholds versus shock amplitude for various values of the nondimensional design constraints of the ROM are generated. These curves will present valuable information about the interaction between the shock and electrostatic forces and how to utilize this interaction to build new devices and propose new technologies.     

Failure analysis of a thin-film nitride MEMS package

In this paper, the failure mechanism of a thin-film nitride MEMS package is studied by an integrated test structure. The cause of the failure is investigated by advanced characterization techniques and accelerated tests on the packaging material. From the research, we can conclude that PECVD silicon nitride is a proper sealing material for thin-film packaging because of its good sealing property. However, outgassing of this material, at elevated temperature, remains the main concern for the reliability.     

Failure analysis of micro-heating elements suspended on thin membranes

We report on the degradation of platinum micro-heating elements operating at high temperatures. Devices with platinum heaters suspended on micro-machined dielectric membranes were self-heated at high temperature until failure. Optical and SEM observations combined with mechanical deformation measurements and Thermal Laser Stimulation techniques were used to analyze the failure mechanisms of the micro-heating elements. Platinum atoms migration and breaking of the membrane were two failure modes observed. At high temperature, the migration of the platinum atoms was linked to the mechanical stress in the dielectric membrane. The Thermal Laser Stimulation technique revealed the formation of vertical as well as lateral thermocouples at mechanically deformed areas. One explanation proposed is that those thermocouples are the result of Si diffusion from the Si₃N₄ membrane into the platinum heater as well as electro-stress migration of platinum atoms.     

Numerical and experimental comparison of MEMS suspended plates dynamic behaviour under squeeze film damping effect

Dynamic behaviour of oscillating perforated microplates under the effect of squeeze film damping is analyzed. Two simplified finite element numerical approaches are adopted to predict damping and stiffness effects transferred from the surrounding ambient air to oscillating structures; the effects of holes cross section and plate dimension are observed. The applicability of the numerical models in terms of precision of results and mesh density is investigated. Results obtained by FE models are compared with experimental measurements conduced by an optical interferometric microscope.     

RF operation of MOSFETs under integrated inductors

This paper presents an in-depth analysis of the operation of a CMOS single-chip three-dimensional inductor over a MOSFET structure at RF frequencies. Active circuitry is placed underneath the integrated inductors in order to take advantage of the vacant space. Measurements indicate that the operation of the MOSFET and of the inductor is affected in a predictable manner. The paper theoretically investigates the interaction between the two elements,analyzes the origin of all appearing effects and compares the theory with the experimental data from a typical CMOS process. Moreover, this study proposes possible applications and design guides and confirms the attractiveness of the inductor over MOSFET placement.     

Design and fabrication of deep submicron CMOS technology compatible suspended high-Q spiral inductors

In this paper, deep submicron complementary metal-oxide-semiconductor (CMOS) process compatible high-Q suspended spiral on-chip inductors were designed and fabricated. In the design, the electromagnetic solver, SONNET, and the finite element program, ANSYS, were used for electrical characteristics, maximum endurable impact force, and thermal conduction simulations, respectively. Based on the design, suspended spiral inductors with different air cavity structures, i.e., diamond opening, circle opening, triangle opening, and full suspended with pillar supports were developed for various applications. Among these structures, the suspended inductor with pillar support possesses the highest Q/sub max/ (maximum of quality factor) of 6.6 at 2 GHz, the least effective dielectric constant of 1.06, and the lowest endurable impact force 0.184 Newton. On the other hand, the spiral inductor with diamond opening has a lowest Q/sub max/ of 4.3, the largest effective dielectric constant of 3.44 and highest endurable impact force 4 Newton. The former is suitable for station telecommunication applications in which the mechanical vibration is not a serious concern, while the latter can be used for mobile telecommunication applications subject to strong mechanical vibrations. Additionally, the conventional on-chip spiral inductor embraced by SiO/sub 2/ with a dielectric constant of 4 was prepared for comparison and found its Q/sub max/ is 3.8 at 1.2 GHz.     

组件架构系统的失效模式和影响分析

文章对安全性分析技术失效模式和影响分析(Failure Mode and Effect Analysis,FMEA)在组件架构系统中的应用和处理进行了研究。基于组件构造系统的特点和FMEA方法,构造了基于消息序列图确定FMEA的失效模式。     

Reliability assessment of a MEMS microphone under mixed flowing gas environment and shock impact loading

In this work the reliability of a Micro-Electro-Mechanical Systems (MEMS) microphone is studied through two accelerated life tests, mixed flowing gas (MFG) testing and shock impact testing. The objective is to identify the associated failure mechanisms and improve the reliability of MEMS devices. Failure analyses are carried out by using various tools, such as optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS). Finite element analysis is also conducted to study the complex contact behaviors among the MEMS elements during shock impact testing. The predicted failure sites are in agreement with the experimental findings.     

MEMS器件在冲击下的可靠性

MEMS器件在制造、运输和使用过程中不可避免地受到不同程度的冲击作用,分析和认识MEMS器件在冲击下的响应和失效模式,对提高器件的耐冲击和可靠性具有一定的指导意义。本文综述了MEMS器件的冲击测试和理论分析方法,对MEMS器件的可靠性设计具有一定参考价值。     

MEMS麦克风的失效机理及失效分析

MEMS麦克风是将音频信号转换成电信号的微型传感器,其工作过程涉及到声学、机械学和微电子学等学科。随着MEMS麦克风封装尺寸的不断缩小和声学性能的不断提升,以电学测试结果作为失效分析出发点的传统半导体失效分析方法越来越难以满足MEMS麦克风失效分析的需要。针对MEMS麦克风独特的封装结构和工作原理,其失效分析方法主要包括声学性能测试、机械性能测试和电学性能测试,并结合传统的半导体物理失效分析手段来找到真正的失效原因及失效机理。     

Failure mechanisms of lead-free chip scale package interconnections under fast mechanical loading

The reliability of chip scale package (CSP) components against mechanical shocks has been studied by employing statistical, fractographic, and microstructural research methods. The components having high tin (Sn0.2Ag0.4Cu) solder bumps were reflow soldered with the Sn3.8Ag0.7Cu (wt.%) solder paste on Ni(P)|Au- and organic solderability preservative (OSP)-coated multilayer printed wiring boards (PWBs), and the assemblies were subjected to the standard drop test procedure. The statistically significant difference in the reliability performance was observed: the components soldered on Cu|OSP were more reliable than those soldered on Ni(P)|Au. Solder interconnections on the Cu|OSP boards failed at the component side, where cracks propagated through the (Cu,Ni)₆Sn₅ reaction layer, whereas interconnections on the Ni(P)|Au boards failed at the PWB side exhibiting the brittle fracture known also as “black pad.” In the first failure mode, which is not normally observed in thermally cycled assemblies, cracks propagate along the intermetallic layers due to the strong strain-rate hardening of the solder interconnections in drop tests. Owing to strain-rate hardening, the stresses in the solder interconnections increase very rapidly in the corner regions of the interconnections above the fracture strength of the ternary (Cu,Ni)₆Sn₅ phase leading to intermetallic fracture. In addition, because of strain-rate hardening, the recrystallization of the as-soldered microstructure is hindered, and therefore the network of grain boundaries is not available in the bulk solder for cracks to propagate, as occurs during thermal cycling. In the black pad failure mode, cracks nucleate and propagate in the porous NiSnP layer between the columnar two-phase (Ni₃P+Sn) layer and the (Cu,Ni)₆Sn₅ intermetallic layer. The fact that the Ni(P)|Au interconnections fail at the PWB side, even though higher stresses are generated on the component side, underlines the brittle nature of the reaction layer.     

Nonlinear characteristics of on-chip spiral inductors under high RF power

This paper explores silicon CMOS on-chip spiral inductors performance degradation under high RF power. A novel methodology to calibrate and characterize on-chip spiral inductor with large signal inputs (high/medium power) is presented. Experiments showed 12% degradation of quality factor in a particular inductor design when 34 dBm RF power was applied. The degradation of quality factor of inductor can be attributed to a local self heating effect. Thermal imaging of such an inductor under high RF power validates the hypothesis.     

RF MEMS开关失效因素的COMSOL仿真

针对RF MEMS开关的可靠性问题,利用有限元软件COMSOL,对悬臂式RF MEMS开关周围的电场分布,开关上的电荷分布和本征频率进行了分析;并研究了在静电场和结构力场耦合作用下悬臂梁的内应力情况,找出开关损坏的可能部位,探索RF MEMS失效的机理,为悬臂式RF MEMS开关的优化改进提供理论依据。     

Modeling and analysis of 3-D solenoid embedded inductors

Investigation of the statistical variation of integrated passive components is crucial for designing and characterizing the performance of multichip module (MCM) substrates. In this paper, the statistical analysis of three-dimensional (3-D) solenoid inductors manufactured in a multilayer low-temperature cofired ceramic (LTCC) process is presented. A set of integrated inductor structures is fabricated, and their scattering parameters are measured for a range of frequencies from 50 MHz to 5 GHz. Using optimized equivalent circuits obtained from HSPICE, mean and absolute deviation is calculated for each component of each device model. Monte Carlo Analysis for the inductor structures is then performed using HSPICE. Using a comparison of the Monte Carlo results and measured data, it is determined that for even a small number of sample structures, the statistical variation of the component values provides an accurate representation of the overall inductor performance     

Steady-state analysis of an interleaved boost converter withcoupled inductors

Boost converters are widely used as power-factor corrected preregulators. In high-power applications, interleaved operation of two or more boost converters has been proposed to increase the output power and to reduce the output ripple. A major design criterion then is to ensure equal current sharing among the parallel converters. In this paper, a converter consisting of two interleaved and intercoupled boost converter cells is proposed and investigated. The boost converter cells have very good current sharing characteristics even in the presence of relatively large duty cycle mismatch. In addition, it can be designed to have small input current ripple and zero boost-rectifier reverse-recovery loss. The operating principle, steady-state analysis, and comparison with the conventional boost converter are presented. Simulation and experimental results are also given     

Failure mode analysis of oxide VCSELs in high humidity and high temperature

High-speed fiber-optic transceiver modules using parallel optics require that oxide-confined vertical-cavity surface-emitting lasers (VCSELs) be moisture resistant in a non-hermetic package. We have found that the conventional storage 85/85 (85/spl deg/C/85% relative humidity) test does not adequately characterize oxide VCSELs moisture resistance. We have identified three failure modes in the oxide VCSELs under operating conditions in high humidity. In this paper, we discuss the failure mechanisms including dislocation growth, semiconductor cracks, and aperture surface degradation, all associated with operation under high relative humidity. Understanding of these failure modes has led to more appropriate qualification standards and environmentally robust oxide VCSELs.     

基于FMECA和CARMES的飞腾通用模块失效模式分析

目前市场上已形成以飞腾、龙芯、申威等为代表的国产处理器,但是对其的可靠性研究还比较少.为研究国产处理器的可靠性水平,文中以FT1500A/16处理器为例,针对其最小系统通用模块,基于可靠性维修性保障性工程软件(CARMES),采用经典可靠性分析方法——故障模式、影响及危害性分析(FMECA)方法对飞腾通用模块开展可靠性...