MEMS for wireless communications: 'from RF-MEMS components to RF-MEMS-SiP'
TL;DR: In this article, the progress in RF-MEMS from a device and integration perspective is reviewed, and the worldwide state-of-the-art of RFMEMS devices including switches, variable capacitors, resonators and filters are described.
Abstract: Wireless communication has led to an explosive growth of emerging consumer and military applications of radio frequency (RF), microwave and millimeter wave circuits and systems. Future personal (hand-held) and ground communications systems as well as communications satellites necessitate the use of highly integrated RF front-ends, featuring small size, low weight, high performance and low cost. Continuing chip scaling has contributed to the extent that off-chip, bulky passive RF components, such as high-Q inductors, ceramic and SAW filters, varactor diodes and discrete PIN diode switches, have become limiting. Micro-machining or MEMS technology is now rapidly emerging as an enabling technology to yield a new generation of high-performance RF-MEMS passives to replace these off-chip passives in wireless communication (sub)systems. This paper reviews the progress in RF-MEMS from a device and integration perspective. The worldwide state-of-the-art of RF-MEMS devices including switches, variable capacitors, resonators and filters are described. Next, it is stipulated how integration of RF-MEMS passives with other passives (as inductors, LC filters, SAW devices, couplers and power dividers) and, active circuitry (ASICs, RFICs) can lead to the so-called RF-MEMS system-in-a-package (RF-MEMS-SiP) modules. The evolution of the RF-MEMS-SiP technology is illustrated using IMEC's microwave multi-layer thin-film MCM-D technology which today already serves as a technology platform for RF-SiP.
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TL;DR: Lithium ion batteries, in which lithium ions shuttle between an insertion cathode and an insertion anode (e.g., carbon), emerged as the power source of choice for the highperformance rechargeable-battery market.
Abstract: The worldwide thirst for portable consumer electronics in the 1990s had an enormous impact on portable power. Lithium ion batteries, in which lithium ions shuttle between an insertion cathode (e.g., LiCoO2) and an insertion anode (e.g., carbon), emerged as the power source of choice for the highperformance rechargeable-battery market. The performance advantages were so significant that lithium ion batteries not only replaced Ni-Cd batteries but left the purported successor technology, nickel-metal hydride, in its wake.1 The thick metal plates of * To whom correspondence should be addressed. J.W.L: e-mail, jwlong@ccs.nrl.navy.mil; telephone, (+1)202-404-8697. B.D.: e-mail, bdunn@ucla.edu; telephone, (+1)310-825-1519. D.R.R.: e-mail, rolison@nrl.navy.mil; telephone, (+1)202-767-3617. H.S.W.: e-mail, white@chem.utah.edu; telephone, (+1)810-585-6256. † Naval Research Laboratory. ‡ UCLA. § University of Utah. 4463 Chem. Rev. 2004, 104, 4463−4492
1,167 citations
TL;DR: In this paper, the pull-in instability in microelectromechanical (MEMS) resonators was studied and the authors proposed a low-voltage MEMS RF switch actuated with a combined DC and AC loading, which uses a voltage much lower than the traditionally used DC voltage.
Abstract: We study the pull-in instability in microelectromechanical (MEMS) resonators and find that characteristics of the pull-in phenomenon in the presence of AC loads differ from those under purely DC loads. We analyze this phenomenon, dubbed dynamic pull-in, and formulate safety criteria for the design of MEMS resonant sensors and filters excited near one of their natural frequencies. We also utilize this phenomenon to design a low-voltage MEMS RF switch actuated with a combined DC and AC loading. The new switch uses a voltage much lower than the traditionally used DC voltage. Either the frequency or the amplitude of the AC loading can be adjusted to reduce the driving voltage and switching time. The new actuation method has the potential of solving the problem of high driving voltages of RF MEMS switches.
421 citations
Cites background from "MEMS for wireless communications: '..."
...The major drawbacks of these devices are their requirement of high driving voltages and low reliability [3, 14 ]....
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TL;DR: Traditional as well as innovative and emerging approaches to MEMS and IC integration are reviewed, including approaches based on the hybrid integration of multiple chips (multi- chip solutions) as wellAs system-on-chip solutions based on wafer-level monolithic integration and heterogeneous integration techniques.
Abstract: The majority of microelectromechanical system (MEMS) devices must be combined with integrated circuits (ICs) for operation in larger electronic systems. While MEMS transducers sense or control phys ...
216 citations
TL;DR: There are a variety of possible methods of integrating and packaging MEMS and IC components, and the technology of choice strongly depends on the device, the field of application and the commercial requirements.
Abstract: The majority of microelectromechanical system (MEMS) devices must be combined with integrated circuits (ICs) for operation in larger electronic systems. While MEMS transducers sense or control physical, optical or chemical quantities, ICs typically provide functionalities related to the signals of these transducers, such as analog-to-digital conversion, amplification, filtering and information processing as well as communication between the MEMS transducer and the outside world. Thus, the vast majority of commercial MEMS products, such as accelerometers, gyroscopes and micro-mirror arrays, are integrated and packaged together with ICs. There are a variety of possible methods of integrating and packaging MEMS and IC components, and the technology of choice strongly depends on the device, the field of application and the commercial requirements. In this review paper, traditional as well as innovative and emerging approaches to MEMS and IC integration are reviewed. These include approaches based on the hybrid integration of multiple chips (multi-chip solutions) as well as system-on-chip solutions based on wafer-level monolithic integration and heterogeneous integration techniques. These are important technological building blocks for the More-Than-Moore paradigm described in the International Technology Roadmap for Semiconductors. In this paper, the various approaches are categorized in a coherent manner, their merits are discussed, and suitable application areas and implementations are critically investigated. The implications of the different MEMS and IC integration approaches for packaging, testing and final system costs are reviewed.
174 citations
TL;DR: In this article, the authors used a parallel array of corner-coupled polysilicon square plate resonators to achieve a motional resistance reduction of 5.9X.
Abstract: Substantial reductions in vibrating micromechanical resonator series motional resistance Rx have been attained by mechanically coupling and exciting a parallel array of corner-coupled polysilicon square plate resonators. Using this technique with seven resonators, an effective Rx of 480 Omega has been attained at 70 MHz, which is more than 5.9X smaller than the 2.82 kOmega exhibited by a stand-alone transverse-mode corner-supported square resonator, and all this achieved while still maintaining an effective Q>9000. This method for Rx-reduction is superior to methods based on brute force scaling of electrode-to-resonator gaps or dc-bias increases, because it allows a reduction in Rx without sacrificing linearity, and thereby breaks the Rx versus dynamic range tradeoff often seen when scaling. This paper also compares two types of anchoring schemes for transverse-mode square micromechanical resonators and models the effect of support beam parameters on resonance frequency
141 citations
References
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Book•
01 Jan 1997TL;DR: The second edition of the Fundamentals of Microfabrication as discussed by the authors provides an in-depth coverage of the science of miniaturization, its methods, and materials, from the fundamentals of lithography through bonding and packaging to quantum structures and molecular engineering.
Abstract: MEMS technology and applications have grown at a tremendous pace, while structural dimensions have grown smaller and smaller, reaching down even to the molecular level. With this movement have come new types of applications and rapid advances in the technologies and techniques needed to fabricate the increasingly miniature devices that are literally changing our world.A bestseller in its first edition, Fundamentals of Microfabrication, Second Edition reflects the many developments in methods, materials, and applications that have emerged recently. Renowned author Marc Madou has added exercise sets to each chapter, thus answering the need for a textbook in this field.Fundamentals of Microfabrication, Second Edition offers unique, in-depth coverage of the science of miniaturization, its methods, and materials. From the fundamentals of lithography through bonding and packaging to quantum structures and molecular engineering, it provides the background, tools, and directions you need to confidently choose fabrication methods and materials for a particular miniaturization problem.New in the Second EditionRevised chapters that reflect the many recent advances in the fieldUpdated and enhanced discussions of topics including DNA arrays, microfluidics, micromolding techniques, and nanotechnology In-depth coverage of bio-MEMs, RF-MEMs, high-temperature, and optical MEMs.Many more links to the WebProblem sets in each chapter
2,334 citations
TL;DR: In this paper, the authors concentrate on electrostatic switches at 0.1-100 GHz with high reliability (100 million to 10 billion cycles) and wafer-scale manufacturing techniques.
Abstract: MEMS switches are devices that use mechanical movement to achieve a short circuit or an open circuit in the RF transmission line. RF MEMS switches are the specific micromechanical switches that are designed to operate at RF-to-millimeter-wave frequencies (0.1 to 100 GHz). The forces required for the mechanical movement can be obtained using electrostatic, magnetostatic, piezoelectric, or thermal designs. To date, only electrostatic-type switches have been demonstrated at 0.1-100 GHz with high reliability (100 million to 10 billion cycles) and wafer-scale manufacturing techniques. It is for this reason that this article will concentrate on electrostatic switches.
1,066 citations
"MEMS for wireless communications: '..." refers background in this paper
...see [25, 33, 34, 37 ] containing reviews on RF-MEMS switches....
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...RF-MEMS switches offer great potential benefits over semiconductor switches in terms of a high isolation, in particular at high frequencies (>30 GHz), and a low loss over a wide frequency range (in particular compared to FETs at the higher frequencies), extremely low standby power consumption (in particular compared to PIN diodes) and the excellent linearity characteristics [25, 34, 37 , 54, 55]....
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Book•
30 Nov 2000TL;DR: The main aim is to provide an introduction to MEMS by describing the processes and materials available and by using examples of commercially available devices, and the concept of using MEMS devices as key elements within complex systems (or even microsystems!) is explored.
Abstract: If you've not been involved in MEMS (MicroElectroMechanical Systems) technology or had the cause to use MEMS devices, then you may wonder what all the fuss is about. What are MEMS anyway? What's the difference between MEMS and MST (MicroSystems Technology)? What are the advantages over existing technologies? If you have ever found yourself pondering over such questions, then this book may be for you. As the title suggests, the main aim is to provide an introduction to MEMS by describing the processes and materials available and by using examples of commercially available devices. The intended readership are those technical managers, engineers, scientists and graduate students who are keen to learn about MEMS but have little or no experience of the technology. I was particularly pleased to note that Maluf has dedicated a whole chapter to the important (and often difficult) area of packaging. The first three chapters provide a general overview of the technology. Within the first three pages we are introduced to the MEMS versus MST question, only to discover that the difference depends on where you live! The United States prefer MEMS, while the Europeans use the handle MST. (Note to self: tell colleagues in MEMS group at Southampton). A good account is given of the basic materials used in the technology, including silicon, silicon oxide/nitride/carbide, metals, polymers, quartz and gallium arsenide. The various processes involved in the creation of MEMS devices are also described. A good treatment is given to etching and bonding in addition to the various deposition techniques. It was interesting to note that the author doesn't make a big issue of the differences between bulk and surface micromachined devices; the approach seems to be `here's your toolbag - get on with it'. One of the great strengths of this book is the coverage of commercial MEMS structures. Arising as they have, from essentially a planar technology, MEMS devices are often elaborate three-dimensional creations, and 2D drawings don't do them much justice. I have to say that I was extremely impressed with the many aesthetic isometric views of some of these wonderful structures. Pressure sensors, inkjet print nozzles, mass flow sensors, accelerometers, valves and micromirrors are all given sufficient treatment to describe the fundamental behaviour and design philosophy, but without the mathematical rigour expected for a traditional journal paper. Chapter 5 addresses the promise of the technology as a means of enabling a new range of applications. The concept of using MEMS devices as key elements within complex systems (or even microsystems!) is explored. The so-called `lab-on-a-chip' approach is described, whereby complex analytical systems are integrated onto a single chip together with the associated micropumps and microvalves. The design and fabrication of MEMS devices are important issues by themselves. A key area, often overlooked, is that of packaging. Painstaking modelling and intricate fabrication methodologies can produce resonator structures oscillating at precisely, say, 125 kHz. The device is then mounted in a dual-in-line carrier and the frequency shifts by 10 kHz because of the additional internal stresses produced. Packaging issues can't be decoupled from those of the micromachined components. Many of these issues, such as protective coatings, thermal management, calibration etc, are covered briefly in the final chapter. Overall, I found this book informative and interesting. It has a broad appeal and gives a good insight into this fascinating and exciting subject area. Neil White
770 citations
"MEMS for wireless communications: '..." refers background in this paper
...Perhaps the only technology at present with the potential to enable the integration of all these passives is micromachining or MEMS (micro-electro-mechanical system or structure) technology [ 23 , 24]....
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...MEMS technology refers to the micromachining of (structural) materials [ 23 , 24]....
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TL;DR: In this article, a method to fabricate nanometer scale mechanical structures from bulk, single-crystal Si substrates is presented, which does not require low pressure chemical vapor deposition of intermediate masking layers, and the final step in the processing uses a dry etch technique, avoiding the difficulties encountered from surface tension effects when wet processing mechanically delicate or large aspect ratio structures.
Abstract: We report on a method to fabricate nanometer scale mechanical structures from bulk, single-crystal Si substrates. A technique developed previously required more complex fabrication methods and an undercut step using wet chemical processing. Our method does not require low pressure chemical vapor deposition of intermediate masking layers, and the final step in the processing uses a dry etch technique, avoiding the difficulties encountered from surface tension effects when wet processing mechanically delicate or large aspect ratio structures. Using this technique, we demonstrate fabrication of a mechanical resonator with a fundamental resonance frequency of 70.72 MHz and a quality factor of 2 x 10^(4).
560 citations
TL;DR: The recent progress in MEMS for radio frequency (RF) applications from a device perspective is reviewed in this article, where switches and relays, tunable capacitors, integrated inductors, mechanical resonators and filters, and some representative microwave and millimetre-wave components are discussed.
Abstract: This paper reviews the recent progress in MEMS for radio frequency (RF) applications from a device perspective. RF MEMS devices reviewed include switches and relays, tunable capacitors, integrated inductors, mechanical resonators and filters, and some representative microwave and millimetre-wave components. Important device parameters are highlighted, as they have significant contributions to the performance of the final products in which the devices are used. The challenges and statuses of these RF MEMS devices are outlined and discussed. The intent of this topical review is to provide perspective to newcomers in the field, and empower potential end-users with an overall device picture, current status, and a vision of their ultimate performance capabilities.
552 citations