1,721,128 research outputs found
Reliability of MEMS: A perspective on failure mechanisms, improvement solutions and best practices at development level
No full textReliability of MEMS (MicroElectroMechanical-Systems) devices is a crucial aspect as it can discriminate the successful from partially or totally missed reaching of Microsystem technology based market products. However, the topic of MEMS reliability is significantly articulated, as it comprises numerous physics of failure and diverse failure mechanisms. Thereafter, it requires a pronounced sensitivity related to the actual operation conditions (environmental and functional) of the Microsystem device within the final application. In other words, reliability of MEMS is nowadays regarded as a standalone transversal discipline that must be seriously taken into account already from the early design phase. The purpose of this paper is to provide the reader at first with basic knowledge around the concept of reliability. Thereafter, the most relevant physics of failure and failure mechanisms typical of MEMS are grouped and briefly discussed, with specific attention to their employment in the field of displays. A synthetic review of valuable solutions to improve specific reliability aspects of MEMS devices for diverse applications is then proposed to the reader. Eventually, a brief discussion focused on best practices to address properly reliability during the whole development chain of innovative MEMS based products completes the contribution. It is a belief of the author that the particular blend of topics and aspects reported in the following pages, as well as the attitude of considering reliability as a transversal discipline of science, contribute to provide this contribution with an important benefit if compared to the reviews on reliability of MEMS previously published in literature
Optimum design of MEMS/RF-MEMS: an iteration flow with the simulation phase
No full textDesign of RF-MEMS is an essential step in defining the features and characteristics of new MEMS/RF MEMS devices, prior to their manufacturing. However, the design phase of Microsystems can play an important role also for what concerns the path leading to the realization and prototyping of MEMS/RF-MEMS new concepts, able to satisfy the requested specifications and performance. As it is well known, the design optimization of novel MEMS and RF-MEMS devices is not an easy and straightforward task, because of the multi-physical behaviour characterizing them [1]. Regardless of the sensing or actuation function a certain MEMS device is supposed to realize, its behaviour always involves the coupling of the mechanical domain with physical magnitudes belonging to some other domains. For example, a capacitive MEMS accelerometer couples the mechanical domain (displacement of the proof mass proportional to the imposed acceleration) to the electrical domain (capacitance variation proportion to the proof mass displacement) [1]. The case of RF-MEMS is even more complex, as the coupling takes place between three different domains, namely, the mechanical and electrical for what concerns the actuation and controlling of the MEMS movable parts and membranes, and the electromagnetic one, concerning the filtering and conditioning of one or more RF signals operated by the Microsystems-based device or network. Of course, each physical domain involved brings in additional Degrees Of Freedom (DOFs) that have to be accounted for in the design phase, as well as increasing trade-offs between the device characteristics. For example, in designing an RF-MEMS ohmic switch a target could be reducing the pull-in voltage (i.e. the activation voltage) to make the device compatible with the typical bias levels of CMOS circuitry. Such a target can be obtained by acting on the design of the flexible suspensions, in such a way to reduce their effective elastic constant. However, a low actuation voltage means also a reduced contact pressure on the ohmic contacts when the switch is actuated, leading to a worse ohmic contact and to the subsequent increase of the RF signal attenuation, operated by the micro-relay (in the closed configuration). The just mentioned case demonstrates that the links and trade-offs between the characteristics of MEMS and RF-MEMS belonging to the involved physical domains are numerous and must be carefully identified and managed
Can MEMS Deliver for 5G Mobile Networks?
No full textSo much promise has been laid on MEMS technology as a solution for countless problems, but with the coming of 5G wireless networks, MEMS components may finally have a chance to perform
Practical Guide to RF-MEMS
No full textCloses the gap between hardcore-theoretical and purely experimental RF-MEMS books.
The book covers, from a practical viewpoint, the most critical steps that have to be taken in order to develop novel RF-MEMS device concepts. Prototypical RF-MEMS devices, both including lumped components and complex networks, are presented at the beginning of the book as reference examples, and these are then discussed from different perspectives with regard to design, simulation, packaging, testing, and post-fabrication modeling. Theoretical concepts are introduced when necessary to complement the practical hints given for all RF-MEMS development stages.
Provides researchers and engineers with invaluable practical hints on how to develop novel RF-MEMS device concepts
Covers all critical steps, dealing with design, simulation, optimization, characterization and fabrication of MEMS for radio-frequency applications
Addresses frequently disregarded issues, explicitly treating the hard to predict interplay between the three-dimensional device structure and its electromagnetic functionality
Bridges theory and experiment, fundamental concepts are introduced with the application in mind, and simulation results are validated against experimental results
Appeals to the practice-oriented R&D reader: design and simulation examples are based on widely known software packages such as ANSYS and the hardware description language Verilog
Microsystem Based Energy Harvesting (EH-MEMS): Powering Pervasivity of the Internet of Things (IoT) - A Review With Focus on Mechanical Vibrations
Full text linkThe paradigm of the Internet of Things (IoT) appears to be the common denominator of all distributed sensing applications, providing connectivity, interoperability and communication of smart entities (e.g. environments, objects) within a pervasive network. The IoT demands for smart, integrated, miniaturised and low-energy wireless nodes, typically powered by non-renewable energy storage units (batteries). The latter aspect poses constraints as batteries have a limited lifetime and often their replacement is impracticable. Availability of zero-power energy-autonomous technologies, able to harvest (i.e. convert) and store part of the energy available in the surrounding environment (vibrations, thermal gradients, electromagnetic waves) into electricity to supply wireless nodes functionality, would fill a significant part of the technology gap limiting the wide diffusion of efficient and cost effective IoT applications. Given the just depicted scenario, the realisation of miniaturised Energy Harvesters (EHs) leveraging on MEMS technology (MicroElectroMechanical-Systems), i.e. EH-MEMS, seems to be a key-enabling solution able to conjugate both main driving requirements of IoT applications, namely, energy-autonomy and miniaturisation/integration.
This short review outlines the current state of the art in the field of EH-MEMS, with a specific focus on vibration EHs, i.e. converters capable to convert the mechanical energy scattered in environmental vibrations, into electric power. In particular, the issues in terms of conversion performance arising from EHs scaling down, along with the challenge to extend their operability on a frequency range of vibrations as wider as possible, are going to be discussed in the following
RF-MEMS for High-Performance and Widely Reconfigurable Passive Components - A Review With Focus on Future Telecommunications, Internet of Things (IoT) and 5G Applications
No full textSince its first discussions in literature during late ‘90s, RF-MEMS technology (i.e. Radio Frequency MicroElectroMechanical-Systems) has been showing uncommon potential in the realisation of high-performance and widely reconfigurable RF passives for radio and telecommunication systems. Nevertheless, against the most confident forecasts sparkling around the successful exploitation of RF-MEMS technology in mass-market applications, with the mobile phone segment first in line, already commencing from the earliest years of the 2000s, the first design wins for MEMS-based RF passives have started to be announced just in late 2014. Beyond the disappointment of all the most flattering market forecasts and, on the other hand, the effective employment of RF-MEMS in niche applications (like in very specific space and defence scenarios), there were crucial aspects, not fully considered since the beginning, that impaired the success of such a technology in large-market and consumer applications. Quite unexpectedly, the context has changed rather significantly in recent years. The smartphones market segment started to generate a factual need for highly reconfigurable and high-performance RF passive networks, and this circumstance is increasing the momentum of RF-MEMS technology that was expected to take place more than one decade ago. On a broader landscape, the Internet of Things (IoT) and the even wider paradigm of the Internet of Everything (IoE) seem to be potential fields of exploitation for high-performance and highly reconfigurable passive components in RF-MEMS technology.
This work frames the current state of RF-MEMS market exploitation, analysing the main reasons impairing in past years the proper employment of Microsystem technology based RF passive components. Moreover, highlights on further expansion of RF-MEMS solutions in mobile and telecommunication systems will be briefly provided and discussed
Mixed-Domain Fast Simulation of RF and Microwave MEMS based Complex Networks within Standard IC Development Frameworks
No full textMS technology (MicroElectroMechanical-System) has been successfully employed since a few decades in the sensors/actuators field. Several products available on the market nowadays include MEMS-based accelerometers and gyroscopes, pressure sensors and micro-mirrors matrices. Beside such well-established exploitation of MEMS technology, its use within RF (Radio Frequency) blocks and systems/sub-systems has been attracting, in recent years, the interest of the Scientific Community for the significant RF performances boosting that MEMS devices can enable. Several significant demonstrators of entirely MEMS-based lumped components, like variable capacitors (Hyung et al., 2008), inductors (Zine-El-Abidine et al., 2003) and micro-switches (Goldsmith et al., 1998), are reported in literature, exhibiting remarkable performance in terms of large tuning-range, very high Q-Factor and low-loss, if compared with the currently used components implemented in standard semiconductor technology (Etxeberria & Gracia, 2007, Rebeiz & Muldavin, 1999). Starting from the just mentioned basic lumped components, it is possible to synthesize entire functional sub-blocks for RF applications in MEMS technology. Also in this case, highly significant demonstrators are reported and discussed in literature concerning, for example, tuneable phase shifters (Topalli et al., 2008), switching matrices (Daneshmand & Mansour, 2007), reconfigurable impedance matching networks (Larcher et al., 2009) and power attenuators (Iannacci et al., 2009, a). In all the just listed cases, the good characteristics of RF-MEMS devices lead, on one side, to very highperformance networks and, on the other hand, to enabling a large reconfigurability of the entire RF/Microwave systems employing MEMS sub-blocks. In particular, the latter feature addresses two important points, namely, the reduction of hardware redundancy, being for instance the same Power Amplifier within a mobile phone suitable both in transmission (Tx) and reception (Rx) (De Los Santos, 2002), and the usability of the same RF apparatus in compliance with different communication standards (like GSM, UMTS, WLAN and so on) (Varadan, 2003). Beside the exploitation of MEMS technology within RF transceivers, other potentially successful uses of Microsystems are in the Microwave field, concerning, e.g., very compact switching units, especially appealing to satellite applications for the very reduced weight (Chung et al., 2007), and phase shifters in order to electronically steer short and mid-range radar systems for the homeland security and monitoring applications (Maciel et al., 2007). Given all the examples reported above, it is straightforward that the employment of a proper strategy in aiming at the RF-MEMS devices/networks optimum design is a key-issue in order to gain the best benefits, in terms of performance, that such technology enables to address. This is not an easy task as the behaviour of RF-MEMS transversally crosses different physical domains, namely, electrical, mechanical and electromagnetic, leading to a large number of trade-offs between mechanical and electrical/electromagnetic parameters, that typically cannot be managed within a unique commercial simulation tool. In this chapter, a complete approach for the fast simulation of single RF-MEMS devices as well as of complex networks is presented and discussed in details. The proposed method is based on a MEMS compact model library, previously developed by the author, within a commercial simulation environment for ICs (integrated circuits). Such software tool describes the electromechanical mixed-domain behaviour typical of MEMS devices. Moreover, through the chapter, the electromagnetic characteristics of RF-MEMS will be also addressed by means of extracted lumped element networks, enabling the whole electromechanical and electromagnetic design optimization of the RF-MEMS device or network of interest. In particular, significant examples about how to acc..
RF-MEMS: A development flow driving innovative device concepts to high performance components and networks for wireless applications
No full textIn this work the RF-MEMS technology available at the microfabrication facility of Fondazione Bruno Kessler – FBK (Italy) is discussed. The manufacturing flow, based on surface micromachining of Microsystems, enables the manufacturing of high performance and widely reconfigurable RF-MEMS passive lumped components, i.e. varactors, inductors and micro-relays, as well as complex networks, like phase shifters, impedance tuners, filters, power attenuators, etc. Despite the development flow of the mentioned RF-MEMS in FBK technology is pushed forth from the design to the fabrication, packaging and testing, the focus of this paper will be mainly devoted to modeling and simulation aspects. In conclusion, a couple of fabricated RF-MEMS passives examples will be listed and discussed
RF MEMS passive components for wireless applications
No full textIn this chapter an overview on the different classes of passive components that can be realized in radio frequency microelectromechanical systems (RF MEMS) technology is provided. A particular focus is oriented toward the performance description of RF passive components in MEMS technology, compared to their standard semiconductor counterparts. The crucial applications related aspects of RF MEMS passive components within transceivers and telecommunication platforms will also be stressed, drawing some considerations on the expected future trends in the diffusion of such a technology within large scale market applications
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