Characterization of an embedded RF-MEMS switch

An RF-MEMS capacitive switch for mm-wave integrated circuits, embedded in the BEOL of 0.25μm BiCMOS process, has been characterized. First, a mechanical model based on Finite-Element-Method (FEM) was developed by taking the residual stress of the thin film membrane into account. The pull-in voltage and the capacitance values obtained with the mechanical model agree very well with the measured values. Moreover, S-parameters were extracted using Electromagnetic (EM) solver. The data observed in this way also agree well with the experimental ones measured up to 110GHz. The developed RF model was applied to a transmit/receive (T/R) antenna switch design. The results proved the feasibility of using the FEM model in circuit simulations for the development of RF-MEMS switch embedded, single-chip multi-band RF ICs

A Review of Micro-Contact Physics for Microelectromechanical Systems (MEMS) Metal Contact Switches

Innovations in relevant micro-contact areas are highlighted, these include, design, contact resistance modeling, contact materials, performance and reliability. For each area the basic theory and relevant innovations are explored. A brief comparison of actuation methods is provided to show why electrostatic actuation is most commonly used by radio frequency microelectromechanical systems designers. An examination of the important characteristics of the contact interface such as modeling and material choice is discussed. Micro-contact resistance models based on plastic, elastic-plastic and elastic deformations are reviewed. Much of the modeling for metal contact micro-switches centers around contact area and surface roughness. Surface roughness and its effect on contact area is stressed when considering micro-contact resistance modeling. Finite element models and various approaches for describing surface roughness are compared. Different contact materials to include gold, gold alloys, carbon nanotubes, composite gold-carbon nanotubes, ruthenium, ruthenium oxide, as well as tungsten have been shown to enhance contact performance and reliability with distinct trade offs for each. Finally, a review of physical and electrical failure modes witnessed by researchers are detailed and examined

Resistive damping implementation as a method to improve controllability in stiff ohmic RF-MEMS switches

This paper presents in detail the entire procedure of calculating the bias resistance of an ohmic RF-MEMS switch, controlled under resistive damping (charge drive technique). In case of a very stiff device, like the North Eastern University switch, the actuation control under resistive damping is the only way to achieve controllability. Due to the short switching time as well as the high actuation voltage, it is not practical to apply a tailored control pulse (voltage drive control technique). Implementing a bias resistor of 33 MΩ in series with the voltage source, the impact velocity of the cantilever has been reduced 80 % (13.2 from 65.9 cm/s), eliminating bouncing and high initial impact force during the pull-down phase. However, this results in an affordable cost of switching time increase from 2.38 to 4.34 μs. During the release phase the amplitude of bouncing has also been reduced 34 % (174 from 255 nm), providing significant improvement in both switching operation phases of the switch. © 2013 Springer-Verlag Berlin Heidelberg

Performance Exploration of Uncertain RF MEMS Switch Design with Uniform Meanders

The design of RF-MEMS Switch is useful for future artificial intelligence applications. Radio detection and range estimation has been employed with RF MEMS technology. Attenuators, limiters, phase shifters, T/R switches, and adjustable matching networks are components of RF MEMS. The proposed RF MEMS technology has been introduced in T/R modules, lenses, reflect arrays, sub arrays and switching beam formers. The uncertain RF MEMS switches have been faced many issues like switching and voltage alterations. This study aims in the direction of design, simulation, model along with RF MEMS switching analysis including consistent curving or meandering. The proposed RF MEMS Switch is a flexure form of the Meanders that attain minimal power in nominal voltage. Moreover, this research work highlights the materials assortment in case of beam along with signal-based dielectric. The performance analysis is demonstrated for various materials that have been utilized in the design purpose. Further, better isolation is accomplished at the range of -31dB necessary regarding 8.06V pull-in voltage through a spring constant valued at 3.588N/m, switching capacitance analysis has been found to be 103 fF at ON state and 7.03pF at OFF state and the proposed switch is optimized to work at 38GHz. The designed RF MEMS switch is giving 30% voltage improvement; switching frequency is improved by 21.32% had been attained, which are outperformance the methodology and compete with present technology

RF-MEMS Switches Designed for High-Performance Uniplanar Microwave and mm-Wave Circuits

Radio frequency microelectromechanical system (RF-MEMS) switches have demonstrated superior electrical performance (lower loss and higher isolation) compared to semiconductor-based devices to implement reconfigurable microwave and millimeter (mm)-wave circuits. In this chapter, electrostatically actuated RF-MEMS switch configurations that can be easily integrated in uniplanar circuits are presented. The design procedure and fabrication process of RF-MEMS switch topologies able to control the propagating modes of multimodal uniplanar structures (those based on a combination of coplanar waveguide (CPW), coplanar stripline (CPS), and slotline) will be described in detail. Generalized electrical (multimodal) and mechanical models will be presented and applied to the switch design and simulation. The switch-simulated results are compared to measurements, confirming the expected performances. Using an integrated RF-MEMS surface micromachining process, high-performance multimodal reconfigurable circuits, such as phase switches and filters, are developed with the proposed switch configurations. The design and optimization of these circuits are discussed and the simulated results compared to measurements

Thin Film Encapsulation of Radio Frequency (RF) Microelectromechanical Systems (MEMS) Switches

Microelectromechanical systems (MEMS) radio frequency (RF) switches have been shown to have excellent electrical performance over a wide range of frequencies. However, cost-effective packaging techniques for MEMS switches do not currently exist. This thesis involves the design of RF-optimized encapsulations consisting of dielectric and metal layers, and the creation of a novel thin film encapsulation process to fabricate the encapsulations. The RF performance of several encapsulation designs are evaluated with an analytical model, full wave electromagnetic simulation, and laboratory testing. Performance degradation due to parasitic and reflection losses due to the package is considered, and RF feed-throughs of the transmission line into and out of the package are designed and assessed. Ten different encapsulation designs were created and their RF performance was characterized in terms of insertion loss, return loss, and isolation. A switch without an encapsulation and a switch with a dielectric encapsulation were fabricated and tested by the Air Force Research Laboratory (AFRL), and the test data was used to verify the data from analytical modeling and electromagnetic simulation performed in this work. All results were used to design an optimized encapsulation. An RF MEMS switch with this encapsulation was shown to have an overall insertion loss of less than -0.15 dB at 20 GHz compared to an unencapsulated switch insertion loss of about -0.1 dB. The isolation of the switch was slightly improved with the encapsulation. The fabrication process proposed to manufacture these encapsulations uses a low temperature solder as the metal encapsulation layer. As the final step in the fabrication, the solder is brought to melting temperature and reflowed over the etch holes to form a hermetic encapsulation

Design for reliability applied to RF-MEMS devices and circuits issued from different TRL environments

Ces travaux de thèse visent à aborder la fiabilité des composants RF-MEMS (commutateurs en particulier) pendant la phase de conception en utilisant différents approches de procédés de fabrication. Ça veut dire que l'intérêt est focalisé en comment éliminer ou diminuer pendant la conception les effets des mécanismes de défaillance plus importants au lieu d'étudier la physique des mécanismes. La détection des différents mécanismes de défaillance est analysée en utilisant les performances RF du dispositif et le développement d'un circuit équivalent. Cette nouvelle approche permet à l'utilisateur final savoir comment les performances vont évoluer pendant le cycle de vie. La classification des procédés de fabrication a été faite en utilisant le Technology Readiness Level du procédé qui évalue le niveau de maturité de la technologie. L'analyse de différentes approches de R&D est décrite en mettant l'accent sur les différences entre les niveaux dans la classification TRL. Cette thèse montre quelle est la stratégie optimale pour aborder la fiabilité en démarrant avec un procédé très flexible (LAAS-CNRS comme exemple de baisse TRL), en continuant avec une approche composant (CEA-Leti comme moyenne TRL) et en finissant avec un procédé standard co-intégré CMOS-MEMS (IHP comme haute TRL) dont les modifications sont impossibles.This thesis is intended to deal with reliability of RF-MEMS devices (switches, in particular) from a designer point of view using different fabrication process approaches. This means that the focus will be on how to eliminate or alleviate at the design stage the effects of the most relevant failure mechanisms in each case rather than studying the underlying physics of failure. The detection of the different failure mechanisms are investigated using the RF performance of the device and the developed equivalent circuits. This novel approach allows the end-user to infer the evolution of the device performance versus time going one step further in the Design for Reliability in RF-MEMS. The division of the fabrication process has been done using the Technology Readiness Level of the process. It assesses the maturity of the technology prior to incorporating it into a system or subsystem. An analysis of the different R&D approaches will be presented by highlighting the differences between the different levels in the TRL classification. This thesis pretend to show how reliability can be improved regarding the approach of the fabrication process starting from a very flexible one (LAAS-CNRS as example of low-TRL) passing through a component approach (CEA-Leti as example of medium-TRL) and finishing with a standard co-integrated CMOS-MEMS process (IHP example of high TRL)

RF-MEMS switches for reconfigurable antennas

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Reconfigurable antennas are attractive for many military and commercial applications where it is required to have a single antenna that can be dynamically reconfigured to transmit or receive on multiple frequency bands and patterns. RF-MEMS is a promising technology that has the potential to revolutionize RF and microwave system implementation for next generation telecommunication applications. Despite the efforts of top industrial and academic labs, commercialization of RFMEMS switches has lagged expectations. These problems are connected with switch design (high actuation voltage, low restoring force, low power handling), packaging (contamination layers) and actuation control (high impact force, wear, fatique). This Thesis focuses on the design and control of a novel ohmic RF-MEMS switch specified for reconfigurable antennas applications. This new switch design focuses on the failure mechanisms restriction, the simplicity in fabrication, the power handling and consumption, as well as controllability. Finally, significant attention has been paid in the switch’s electromagnetic characteristics. Efficient switch control implies increased reliability. Towards this target three novel control modes are presented. 1) Optimization of a tailored pulse under Taguchi’s statistical method, which produces promising results but is also sensitive to fabrication tolerances. 2) Quantification of resistive damping control mode, which produces better results only during the pull-down phase of the switch while it is possible to be implemented successfully in very stiff devices. 3) The “Hybrid” control mode, which includes both aforementioned techniques, offering outstanding switching control, as well as immunity to fabrication tolerances, allowing an ensemble of switches rendering an antenna reconfigurable, to be used. Another issue that has been addressed throughout this work is the design and optimization of a reconfigurable, in pattern and frequency, three element Yagi-Uda antenna. The optimization of the antenna’s dimensions has been accomplished through the implementation of a novel technique based on Taguchi’s method, capable of systematically searching wider areas, named as “Grid-Taguchi” method