Search

This work details an effective dynamic chemical etching technique to fabricate ultra-sharp tips for Scanning Near-Field Microwave Microscopy (SNMM). The protruded cylindrical part of the inner conductor in a commercial SMA (Sub Miniature A) coaxial connector is tapered by a dynamic chemical etching process using ferric chloride. The technique is optimized to fabricate ultra-sharp probe tips with controllable shapes and tapered down to have a radius of tip apex around ∼1 μm. The detailed optimization facilitated the fabrication of reproducible high-quality probes suitable for non-contact SNMM operation. A simple analytical model is also presented to better describe the dynamics of the tip formation. The near-field characteristics of the tips are evaluated by finite element method (FEM) based electromagnetic simulations and the performance of the probes has been validated experimentally by means of imaging a metal-dielectric sample using the in-house scanning near-field microwave microscopy system.

We have demonstrated the capabilities of the scanning microwave microscopy (SMM) technique for measuring ferromagnetic resonance (FMR) spectra in nanometric areas of magnetic samples. The technique is evaluated using three different samples, including a yttrium iron garnet (YIG) polycrystalline bulk sample and a thick YIG film grown by liquid phase epitaxy (LPE). Patterned permalloy (Py) micromagnetic dots have been characterized to assess the performance for imaging applications of the technique, measuring the variation of the magnetic properties of the sample along its surface. The proposed technique may pave the way for the development of high spatially resolved mapping of magnetostatic modes in different nanomagnetic and micromagnetic structures.\ud

U-shaped microwave resonators implemented by RF MEMS switches can be considered the result of a novel design approach for obtaining small-footprint tunable resonators, owing to the bent shape of the resonator and the microsystem solution for changing the frequency of resonance. In this paper, we discuss the design approach for potential configurations of U-shaped structures combined with ohmic RF MEMS switches. Owing to their prospective application in RADAR and satellite systems, the devices were assessed for K-Band operation, specifically for 15 GHz, 20 GHz, and 26 GHz. The ON-OFF states determined by an electrostatic actuation of metal beams composing the RF MEMS ohmic switches allow for selecting different path lengths corresponding to different frequencies. In this contribution, initial configurations were designed and manufactured as a proof-of-concept. The advantages and critical aspects of the designs are discussed in detail.

In this paper, a permalloy layer has been employed in the fabrication of a coupled line electromagnetic bandgap (EMBG) device to tune both amplitude and phase. A magnetically biased microwave coplanar configuration manufactured with evaporated permalloy has been measured, and a circuit modelling has been studied to evaluate the measured effects in terms of variable attenuation and phase shift. Starting from a permalloy made by the mixture 80% nickel and 20% iron content, we fabricated an electromagnetic bandgap (EMBG) structure based on a periodic arrangement of single sections of a transmission line with variable impedance, also including a central region with coupled lines. The bandpass characteristics of the EMBG device can be tuned by changing permalloy's permeability through the application of a DC magnetic field H0 (parallel to the plane of the structure). In particular, using a magnetic field up to 3000 Oe, it was possible to change the phase by ca. 45° and the amplitude by ca. 7 dB in the X band.

We have analyzed the self-action effects in the propagation of surface magnetostatic wave (SMSW) pulses in a 1D magnonic crystal–dielectric–metal structure in which the region of anomalous dispersion controlled by the selection of thickness h of the insulator and ensuring the fulfillment of the Lighthill criterion in the generation of SMSW solitons is formed. It is shown that when the metallization-induced region of anomalous dispersion coincides with the Bragg resonance frequency range, no SMSW solitons form.

Microwave near field microscopy and spectroscopy are currently studied for imaging and local characterization in material science, as a non-invasive diagnostic technique in many fields of interest, encompassing dielectric, magnetic and biological samples. Monitoring cultural heritage artefacts is also possible measuring biodeterioration by near field microwave microscopy, to find bio-inclusions with a non-invasive approach. In this paper, is presented a preliminary work for testing a homemade measurement system for local characterization of plants, to determine the necessary sensitivity to study the changes induced by modification of the bio-sample over the time due to an aging process. Preliminary experimental results, showing the capabilities of the developed system, are shown and discussed. In particular, changes in the order of few ohms can be recorded using an impedance measurement, using both real and imaginary part of a reflected signal, to obtain the losses contribution and their evolution due to the natural aging.

A prototype portable tomographic system for microwave imaging is presented in this paper as non-invasive monitoring to preserve cultural heritage work of art. Initial simulations of the system configuration have been carried out to validate the system architecture. The most significative outputs of these simulations are presented and discussed in the paper. Hence, a first lab microwave tomographic set-up has been developed and tested. The outcomes of this preliminary experiments have driven the development of an optimized portable device for in-situ measurements. A custom-made 3D- printed structure has been built to support the antenna elements of the systems and enclose the target being tested. Transmission measurements between pairs of antennas have been acquired through a vector network analyzer connected to a modular switching matrix, and the data generated have been inverted by an opensource reconstruction algorithm. The results of the tests are here reported. They clearly show the capability of the systems to detect metallic intrusion in heritage samples.

In this work, a thin-film packaging was developed to be used for radio-frequency microelectromechanical system configurations. The fabricated packages are suspended membranes in the multilayer SixNy/aSi/SixNy on conductive coplanar waveguides (CPWs) of different length. Several geometric parameters of the membranes, which are the length, the curvature radius at the vertices of the rectangular base, the density and the diameter of holes on the capping surface, were also varied. The mechanical properties of the suspended membranes were investigated by mechanical simulations and surface profilometry measurements as a function of the geometric parameters. RF characterization was performed to evaluate the impact of the package on the CPW performance. Finally, network analysis was carried out, allowing to clarify the origin of the RF losses measured for the fabricated microdevices.

RF MEMS in low-temperature co-fired ceramics (LTCC) technology have been designed, manufactured and tested for potential utilization in reconfigurable space sub-systems. Specifically, single-pole-single-throw (SPST) and single-pole-double-throw (SPDT) ohmic switch configurations have been studied for wide-band applications. Advantages coming from the measured RF performances and from the integration of RF MEMS by means of the LTCC technology only, to be used also for packaging, are discussed. Furthermore, preliminary on-wafer DC test on a double-pole-double-throw (DPDT) ohmic switch has been done in order to check both the mechanical response and the quality of the ohmic contact (contact resistance).

In this paper is presented the design and fabrication of an Electromagnetic Band Gap (EMBG) resonator in coupled lines configuration, to obtain tunable Magnetostatic Wave (MSW) Band Stop Resonators using a magnetic material, namely YIG (yttrium Iron garnet) biased by means of an external magnetic DC field. In particular, a microwave tunable resonator configuration based on a MSW resonator, working at frequencies up to 16 GHz has been studied. The specific purpose of this work is to analyze the filtering response of coplanar waveguide (CPW) EMBG magnetically tunable resonators in a band stop configuration. Measurements of the S 21 parameter demonstrate an important attenuation with more than 20 dB of the higher order modes. They exhibit a good selectivity obtained by the combination between EMBG resonators and YIG ones in the frequency range 5-18 GHz. Tunable EMBG YIG resonators from 5 GHz to 18 GHz, corresponding to the X band and to the Ku band in the microwave region, which are presently a focus for many ground and space applications, have been studied.

The paper presents a methodology for de-embedding scanning microwave microscopy (SMM) measurements, mainly for semiconductor characterization. Analytical modeling, a parametric study and experimental verification are presented. The proposed methodology is based on the analysis of system response in the linear scale, instead of the dB scale commonly utilized in RF measurements, and on expressing the standard calibration capacitances per unit area. In this way the total measured capacitance is determined by the tip area which is then obtained as a result of the model fitting on the experimental data. Additional evaluation is performed by a straightforward experimental comparison with the usually adopted technique that is based on the electrostatic force microscopy approach curve method. The results obtained by the application of both techniques on the same tip during the same experiment were found to be in good agreement and moreover allowed a detailed discussion on the features of each one of the two methodologies. The paper provides also in this way useful knowledge for the potential users in order to choose the most appropriate technique according to the corresponding SMM application. Display Omitted A methodology for de-embedding scanning microwave microscopy measurements is presented.The proposed analysis is based on the assessment of the SMM system response in the linear scale.The methodology is experimentally evaluated by a straightforward comparison with an EFM based calibration method.Based on the obtained results the features of each methodology are also discussed in details.The paper provides a full picture of the up to date available experimental techniques for de-embedding SMM measurements.

Shunt capacitive radio-frequency microelectromechanical system (RF MEMS) switches were fabricated on silicon substrate and characterized in the RF domain. Various switch typologies were obtained by three different approaches, which are: (1) the change of the bridge geometric parameters, (2) the covering of the actuator with a floating metal, and (3) the deposition of the bridge directly on the actuator. The S parameters of the fabricated switches were measured in the up and down states, observing the impact on the RF performance of the variation of the geometric parameters and the fabrication process. The electromagnetic modelling of the fabricated switches was used to interpret the measured RF behaviour, allowing to elucidate the drawbacks of the non-perfect conforming of the bridge on the actuator. Finally, the reliability of the fabricated RF MEMS switches under a bipolar voltage excitation was evaluated by cycling tests. Hence, the study presented here provides guidelines to solve some issues of the tight correlation between design, fabrication, performance, and reliability of RF MEMS switches, in view of a large-scale development of these devices.

Contact resistance is the main parameter used for assessing the high cycling reliability of RF microelectromechanical (RF-MEMS) switches. In this paper the use of a modified contact material is tested and compared to pure gold in cycling experiments performed on a RF-MEMS switch in shunt capacitive configuration. The modified contact material is a gold-based multilayer with a thin layer of platinum sandwiched between two layers of gold. The experiment consists in comparing devices with the same layout but with different contact material. While the two types of switch start with similar RF performances, the device with the modified material shows a marked improvement in cycling reliability and a lower series resistance up to 106 cycles when compared to gold contact devices.

In this work, an electromagnetic technique for imaging and spectroscopy of materials and devices, suitable for the characterization of MEMS and microelectronics configurations as a function of frequency in the microwave range, will be presented. In particular, near field measurements will be shown for the evaluation of dielectric properties of the materials and for imaging of RF devices. Perspective utilization in the evaluation of quantities having specific interest for the microelectronics and MEMS industries will be discussed, with reference to properties that can be deduced from the measured surface impedance, like the morphology and the frequency dependence of the material properties.

In this work, we present a sensor suitable for performing the spectroscopy on a localized micrometric volume of a generic liquid, in the spectral range comprised between 1 and 20 GHz. The sensor is based on two ungrounded, open-ended coplanar waveguides, acting as Input/Output ports, with a microfluidic channel passing through them. It works by detecting the change of the reflection and transmission of microwaves due to the variation of the dielectric properties characteristic of the liquid. The devices have been designed and numerically simulated to obtain the electromagnetic response in different conditions: an empty channel for having a zero-reference response and for observing variations as a function of liquids filling the channel. We considered standard (i.e., common in literature) liquids (deionized water, ethanol, and glycerol); by means of that set of simulations we were able to start the creation of the calibration curves and defining the sensitivity of the sensor with respect to dielectric properties of the liquid under test. Then, we realized a batch of prototypes utilizing a standard photolithographic process. Later we proceeded to check the operation of the sensors. We recorded experimental data by a Vector Network Analyser connected to the devices by means of microwave probes. Sensors are designed to perform both reflection and transmission measurements on the liquid sample, and local microscopy on a micrometric volume of the solution under test. Actually, the device works avoiding any contact between the metallic parts and the liquid that can flow uncontaminated through the microfluidic channel.

In this paper, the basic principles of Near-Field Microscopy will be reviewed with focus on the micro- and nano-scale resolution configurations for material science measurements. Results on doping profile, dielectric and magnetic properties will be presented, with details on the calibration protocols needed for quantitative estimation of the dielectric constant and of the permeability.

In this paper we present the methodology and the numerical results related to the analysis of aging of the SU-8 polymer when used as a primary layer for the realization of Coplanar Waveguide (CPW) structures. As test devices, we used a set of transmission lines with different lengths and T-shaped open stubs shunt resonators; by using these geometries, we are able to acquire the data in a broadband range, in principle between 1 GHz and 40 GHz. We conduct the analysis by comparing two different technology run: the first wafer with a deposited layer by a 12-year-old SU-8 and the second wafer, with the same photolithographed metallic geometries, with a brand-new processed SU-8 photoresist.

In this paper, we present a sensor suitable for performing the spectroscopy on a localized micrometric volume of a generic liquid, in the spectral range comprised between 1 GHz and 20 GHz. The sensor is based on two ungrounded, open-ended coplanar waveguides, acting as Input/Output ports, with a microfluidic channel passing through them to perform also transmission through the liquid analysis. The sensor has been designed and numerically simulated to obtain the electromagnetic response in different conditions: an empty channel for having a zero-reference response and for observing variations as a function of liquids filling the channel.

In this work, the authors present a technique for the local characterization of the dielectric properties of materials. More in details, a setup will be described, and the related measurement modeling will be discussed. In this way, it is possible to obtain a calibrated and nondestructive determination of the dielectric constant in a submicrometric region; the detection of any surface or buried metallization is a straightforward application for microelectronics. The analysis is performed as a function of the frequency in the microwave range and, further on, the data can be transformed in time domain for one dimensional tomography. The authors will show that microwave spectroscopy can be performed by means of standard coaxial pins employed as probes for measurements both in reflection and transmission mode, giving the information of the frequency dependent properties of the exploited material or structure by means of the measured impedance. Experiments are performed in the range between 1 and 18 GHz, and different dielectric samples are tested. In order to evaluate the surface and subsurface measuring capability, samples obtained by thin metallic film deposition on a silicon wafer and buried by a polymeric layer are realized and characterized.

In this work, thin film packages were developed for radio-frequency microelectromechanical system (RF MEMS) configurations. The fabricated packages are suspended membranes in the multilayer SixNyHz/aSi/SixNyHz on conductive coplanar lines of different length. Several geometric parameters of the membranes, which are the length, the curvature radius at the vertices of the rectangular base, the density and the diameter of holes, were also varied. The mechanical properties of the suspended membranes were investigated by surface profilometry as a function of the geometric parameters. Finally, the RF characterization was performed to evaluate the impact of the package on the coplanar line performance. Hence, the proposed study provides results of crucial importance for the application of thin-film suspended microstructures for the packaging of RF MEMS devices.

In this paper a new method to solve the microwave matching problem of MEMS shunt connected switches is proposed, as an extension of a previously presented approach based on the image parameter formulation. The image phase concept is used to impose the matching condition in the “ON” state of the device, which is the most critical one. Two different configurations are investigated: a single basic cell and double basic cell topologies. For both of them an analytic modeling procedure is developed, and the equations for the synthesis of the structures are derived. In order to provide some examples, the method has been applied to a previously realized MEMS shunt variable capacitor.

RF MEMS in Low-Temperature Co-fired Ceramics (LTCC) technology have been designed, manufactured and tested for potential utilization in reconfigurable space sub-systems. Specifically, single-pole-single-throw (SPST) and single-pole-double-throw (SPDT) ohmic switch configurations have been studied for wide-band applications. Advantages coming from the measured RF performances and from the integration of RF MEMS by means of the LTCC technology only, to be used also for packaging, are discussed.

session poster; International audience; The paper presents an experimental study aiming to highlight the potential of scanning microwave microscopy (SMM) as a non-destructive high precision characterization tool for SOI technology. Two identical SOI wafers having passivated and non-passivated top Si film surfaces have been assessed. Differential microwave measurements were found capable of detecting differences in the structures of the two samples. The results support the conclusion that, after appropriate calibration method, SMM may provide a powerful tool offering nm scale characterization for SOI technology.

Triangular resonators, designed by using Radio Frequency Micro Electro Mechanical Systems (RF MEMS) cantilevers in coplanar waveguide (CPW) configuration, have been proposed, fabricated on alumina and on silicon substrates and tested up to 40 GHz. They can be utilized as building blocks for realizing reconfigurable filters. A triangular split ring resonator has been etched in the central conductor of the CPW transmission line and the split is provided by the presence of a technologically actuated cantilever beam, i.e. with metal directly deposited without the sacrificial layer, to emulate the ideal actuation and to get preliminary information of the expected microwave response in comparison to numerical simulations. Two main configurations of the triangular transmission line have been studied for narrow-band microwave switching, the first one without the MEMS cantilever and the second one with a technologically actuated MEMS cantilever switch. Because of the contributions of both the resonator and the switch, the device has a narrow band filtering feature. Moreover, these geometries can also be characterized in the broad class of metamaterial devices, because the unit cell can be described by negative equivalent electric permittivity and/or magnetic permeability, by means of a transmission line parameters extraction method. This finding contributes to the possibility of miniaturization implementations of the resonating structures. A simple but effective lumped element circuit for the modeling of the single triangular resonator is presented in the end.

In this paper, we present in detail the design, both electromagnetic and mechanical, the fabrication, and the test of the first prototype of a Scanning Microwave Microscope (SMM) suitable for a two-port transmission measurement, recording, and processing the high frequency transmission scattering parameter S21 passing through the investigated sample. The S21 toolbox is composed by a microwave emitter, placed below the sample, which excites an electromagnetic wave passing through the sample under test, and is collected by the cantilever used as the detector, electrically matched for high frequency measurements. This prototype enhances the actual capability of the instrument for a sub-surface imaging at the nanoscale. Moreover, it allows the study of the electromagnetic properties of the material under test obtained through the measurement of the reflection (S11) and transmission (S21) parameters at the same time. The SMM operates between 1 GHz and 20 GHz, current limit for the microwave matching of the cantilever, and the high frequency signal is recorded by means of a two-port Vector Network Analyzer, using both contact and no-contact modes of operation, the latter, especially minded for a fully nondestructive and topography-free characterization. This tool is an upgrade of the already established setup for the reflection mode S11 measurement. Actually, the proposed setup is able to give richer information in terms of scattering parameters, including amplitude and phase measurements, by means of the two-port arrangement.

In this work, microwave characterization of magnetic materials using the scanning microwave microscopy (SMM) technique is presented. The capabilities of the SMM are employed for analyzing and imaging local magnetic properties of the materials under test at the nanoscale. The analyses are performed by acquiring both amplitude and phase of the reflected microwave signal. The changes in the reflection coefficient S-11 are related to the local properties of the material under investigation, and the changes in its magnetic properties have been studied as a function of an external DC magnetic bias. Yttrium iron garnet (YIG) films deposited by RF sputtering and grown by liquid phase epitaxial (LPE) on gadolinium gallium garnet (GGG) substrates and permalloy samples have been characterized. An equivalent electromagnetic transmission line model is discussed for the quantitative analysis of the local magnetic properties. We also observed the hysteretic behavior of the reflection coefficient S11 with an external bias field. The imaging and spectroscopy analysis on the experimental results are evidently indicating the possibilities of measuring local changes in the intrinsic magnetic properties on the surface of the material. (C) 2016 Elsevier B.V. All rights reserved.

Shunt capacitive RF MEMS switches have been developed using III-V technology and employing (tantalum pentoxide) Ta2O5thin films as dielectric layers. In order to evaluate the potential of the Ta2O5thin films for the considered application, the compositional, structural, and electrical characterization of the deposited films has been performed, demonstrating that they are good candidates to be used as dielectric layers for the fabrication of RF MEMS switches. Specifically, Ta2O5films are found to show a leakage current density of few nA/cm2forE∼1 MV/cm and a high dielectric constant of 32. Moreover, the charging process has been investigated, finding that it follows a stretched exponential law. The fabricated switches show actuation voltages in the range 15–20 V, an insertion loss better than −0.8 dB up to 30 GHz, and an isolation of ~−40 dB at the resonant frequency which is around 25 GHz.

In this paper a new approach to manufacture low losses coplanar waveguide (CPW) lines for microwave and millimeter wave signal processing is presented. A photolithographic process is performed by using SU-8 thick negative photo-resist on low resistivity silicon wafers, to obtain CPW lines elevated with respect to the substrate, in order to take advantages, in terms of propagation losses, from transmission line structures which are almost on-the-air.

The analytical modelling of a grounded truncated metallic cone is presented in this work as a contribution to the de-embedding and calibration of a scanning microwave system based on capacitance measurements for imaging and spectroscopy purposes. First, an expression for the capacitance of a uniform cylinder is derived, and successively a procedure to determine an effective uniform cylinder radius for the truncated cone is developed. The truncated cone was chosen as a suitable geometry for the calculation of the stray capacitance versus ground of a metallic tip used for scanning probe microscopy and, more specifically, microwave sensing. An accurate calculation of the aforementioned capacitance is of outmost importance for system calibration in scanning microwave microscopy (SMM) technique.

Shunt capacitive radio-frequency microelectromechanical (RF MEMS) switches were modelled, fabricated and characterized in the K-band domain. Design allowed to predict the RF behaviour of the switches as a function of the bridge geometric parameters. The modelled switches were fabricated on silicon substrate, using a surface micromachining approach. In addition to the geometric parameters, the material structure in the bridge-actuator area was modified for switches fabricated on the same wafer, thanks to the removal/addition of two technological steps of crucial importance for RF MEMS switches performance, which are the use of the sacrificial layer and the deposition of a floating metal layer on the actuator. Surface profilometry analysis was used to check the material layer structure in the different regions of the bridge area as well as to investigate the mechanical behaviour of the moveable bridge under the application of a loaded force. The RF behaviour of all the fabricated switches was measured, observing the impact on the isolation of the manipulation of the bridge size and of the variations in the fabrication process.

In this work, we present the analytical modeling and preliminary experimental results for the choice of the optimal frequencies when performing amplitude and phase measurements with a scanning microwave microscope. In particular, the analysis is related to the reflection mode operation of the instrument, i.e., the acquisition of the complex reflection coefficient data, usually referred as S-11. The studied configuration is composed of an atomic force microscope with a microwave matched nanometric cantilever probe tip, connected by a lambda/2 coaxial cable resonator to a vector network analyzer. The set-up is provided by Keysight Technologies. As a peculiar result, the optimal frequencies, where the maximum sensitivity is achieved, are different for the amplitude and for the phase signals. The analysis is focused on measurements of dielectric samples, like semiconductor devices, textile pieces, and biological specimens. (C) 2015 AIP Publishing LLC.

A methodology towards de-embedding contact mode scanning microwave microscopy (SMM) reflection measurements is presented. A calibration standard that consists of differently doped stripes is required, while the reflection coefficient amplitude |S11|, is modeled and analyzed in the linear scale, instead of the commonly adopted dB scale. This allows the straightforward experimental determination of important parameters such as the effective tip radius and the magnitude of stray capacitances. Values of 145 nm and 22 fF have been obtained respectively. The proposed methodology can be easily and repeatedly performed during the experimental procedure, offering in this way the necessary de-embedding to get an enhanced accuracy on SMM measurements for semiconductors characterization.

Triangular metamaterial resonators, designed by RF MEMS cantilevers in coplanar waveguide (CPW) configuration, have been fabricated on alumina substrate and tested up to 40 GHz. A triangular split ring resonator has been etched in the central conductor of the CPW transmission line and the split is provided by a technologically actuated cantilever beam, i.e. with metal directly deposited without the sacrificial layer, to emulate the ideal actuation. Two main configurations of the triangular transmission line have been studied for narrowband microwave switching, the first one without the MEMS cantilever and the second one with a technologically actuated MEMS cantilever switch. Because of the contributions of both the resonator and the switch, the device has a narrow band switching feature. Moreover, the parameters extraction obtained by both the experiment and the simulation, show a metamaterial behavior of the exploited configuration.

Reflection mode scanning microwave microscopy (SMM) is compared to a newly developed transmission mode imaging hardware for extended scattering S11 and S12 measurements. Transmission mode imaging is realized by an SMA connector placed below the sample to excite an electromagnetic wave towards the cantilever acting as nanoscale-sized receiver structure. The frequency response was investigated between 1–20 GHz and a circuitry model of the SMM matching network was combined with a 3D finite element model of the tip-sample system. Modeling results include the local 3D electric field distribution around the nanoscale cantilever tip in contact to the sample. Reflection mode measurements were calibrated using a simple three error-parameter workflow allowing for quantitative impedance and capacitance imaging. A qualitative agreement was obtained between measurements and SMM models for both S11 and S12.

The paper presents a calibration of scanning microwave microscopy signals for doping profiling in MOS systems. The experimentally obtained S-parameters are matched through a linear relation to the calculated MOS system capacitance and then to doping. The proposed approach is verified by simulations with the equivalent LCR circuit as well as by experimental results obtained on a calibration sample with differently doped areas.

The effect of dispersion on the propagation of linear rectangular pulses of magnetostatic waves in YIG films is studied. With surface magnetostatic waves propagating in YIG filins and composite ferrite-insulator-metal structures. it is demonstrated that, for the near-rectangular phase-unmodulated input pulse and the distance between input and output transducers equal roughly to half the dispersion length of' the pulse, the FWHM of the output pulses is 50-60% of the initial value. This fact can be used for estimating the dispersion coefficient of magnetostatic waves.

Bulk and micromachined magnetostatic wave frequency tunable resonators have been designed, realized, and tested. Four resonator configurations, two on a silicon bulk substrate and other two on a micromachined silicon membrane, have been characterized and compared by measuring their S parameter responses at different dc magnetic bias fields. The frequency has been swept between 2 GHz and 5 GHz for silicon bulk resonators and between 2 GHz and 6.5 GHz for the resonators supported by the silicon membrane. By using the membrane technological solution, the insertion losses for membrane supported resonators decrease by about 18 dB with respect to the bulk silicon supported ones. Moreover, the quality factor measured for these configurations was Q(L)approximate to450, about twice that for silicon bulk supported straight edge resonators. The obtained results demonstrate both: (i) the possibility to combine the magnetostatic wave technology with the micromachining one, and (ii) the improvement of the electrical performances for the resonators supported on a silicon membrane, with a strong decrease in the insertion losses and a doubling of the value for the quality factor. Finally, the obtained electrical response is quite good as compared to the classical alumina-based devices, with the novelty to have realized the resonators in an all-silicon environment.

This paper describes the design, the realization and the experimental characterization of a micromachined band-pass filter with a working frequency of 38GHz. The synthesis of the structure has been carried out by means of the image parameter representation of two-port networks. A coupled line coplanar configuration has been adopted for the filtering network. The good agreement between theoretical and experimental results demonstrates the validity of the proposed design approach. Copyright © 2003 John Wiley & Sons, Ltd.

A 12×12 Switch Matrix Unit featuring silicon RF MEMS assembled on LTCC boards has been developed under a Contract with the European Space Agency (ESA) for satellite communication application. The Switch Matrix is a complete Engineering Model unit, housed in a mechanical box in aluminum with RF coaxial connectors and DC connectors for powering and commanding. To the authors' knowledge, it is the first complex equipment realized in Europe exploiting the advanced features of the RF MEMS and multilayer LTCC technology to achieve a significant mass and size reduction. Full wave simulations of entire structure are reported, as well as test results. Their agreement is good up to the satellite downlink C-band (3.7–4.2 GHz). An insertion loss of −20dB, return loss of −10dB and isolation of 40–45dB have been measured. The matrix is passive (not provided with amplifiers), having a DC power consumption of less than half watt due to the digital command circuitry.

Space components need a ground characterization based on several solicitations, including mechanical and thermal stress, before their final qualification. In this paper, RF MEMS switches designed for redundancy logic have been extensively measured with promising results in terms of thermal and mechanical cycles. Packaging contributions have been also discussed.

This paper presents the design of distributed MEMS phase shifters by means of the image-parameters method. The proposed analytic approach utilizes a more precise modeling of the MEMS device with respect to that one usually adopted in literature. The most important analytic aspects concerning the synthesis technique are presented. As a demonstration of the method a structure characterized by a differential phase shift value of 90° is designed and simulated, exhibiting very good electric performance.

A 12×12 Switch Matrix Unit featuring silicon RF MEMS assembled on LTCC boards has been developed under a Contract with the European Space Agency (ESA) for satellite communication application. The Switch Matrix is a complete Engineering Model unit, housed in a mechanical box in aluminum with RF coaxial connectors and DC connectors for powering and commanding. To the authors' knowledge, it is the first complex equipment realized in Europe exploiting the advanced features of the RF MEMS and multilayer LTCC technology to achieve a significant mass and size reduction. Full wave simulations of entire structure are reported, as well as test results. Their agreement is good up to the satellite downlink C-band (3.7-4.2 GHz). An insertion loss of -20dB, return loss of -10dB and isolation of 40-45dB have been measured. The matrix is passive (not provided with amplifiers), having a DC power consumption of less than half watt due to the digital command circuitry.

The structural stability of Al layers in contact with 3.5 wt.% NaCl water solution was investigated at a temperature of 25 °C and hydrostatic pressures from 1 to 600 atm using neutron reflectometry. A pressure–temperature (P–T) Neutron Reflectometry (NR) cell developed at Los Alamos National Laboratory (LANL) was used to understand the behavior of thin (∼900 A) aluminum layers in contact with saline liquid. Experimental results suggest that in the preliminary stages of corrosion the influence of pressure accelerates the mechanism of interactions of the oxide film with Cl− and H2O with lower speed compared to results found in the literature.

International audience

This paper is focused on the design of the transmission lines utilized in microelectromechanical capacitive shunt connected switches. These transmission lines sections are employed as matching elements to improve the performance of the component in the on state. The image phase parameter is used to develop an analytic procedure for the synthesis of such transmission lines. The proposed method is applied for the design of a switch, adopting for the capacitive element the experimental data of a microelectromechanical device previously realized by the authors.

This paper presents the fabrication processes for micromachined millimetre-wave devices, on two different types of semiconductor substrates. The first process uses micromachining on high-resistivity oriented silicon. A three-layer dielectric membrane, with a total thickness of 1.5 µm is used as support for the millimetre-wave structures. This process was used for the manufacturing of two coupled line filters, with central operating frequencies of 38 and 77 GHz, respectively. The second process is based on GaAs micromachining. For the first time, a 2.2 µm thin GaAs/AlGaAs membrane, obtained by molecular beam epitaxy growth and micromachining of semi-insulating GaAs, is used as a support for millimetre-wave filter structures. Cascaded coplanar waveguide open-end series stubs filter type structures, with central frequencies of 38 and 77 GHz, respectively, were designed and manufactured on a GaAs micromachined substrate. `On wafer' measurements for the filter structures were performed. Losses of less than 1.5 dB at 38 GHz and less than 2 dB at 77 GHz have been obtained for both the silicon as well as for the GaAs-based micromachined filters.

This Special Issue is composed by seven papers, selected and expanded from the contributions presented at the 2014 DTIP Symposium on MEMS and MOEMS (Design, Test, Integration & Packaging of MEMS/MOEMS), held in Cannes, Cote d’Azur on 1–4 April 2014. It was a successful experience in the now long history of the DTIP Symposium, chaired by Bernard COURTOIS, CMP, Grenoble, France, with the significant contribution of the Vice General Chair Pascal NOUET, LIRMM, Montpellier, France and the Co-Chair Jean Michel KARAM, MEMSCAP, Bernin, France. This edition of the Symposium ended with the passing of the baton between Bernard Courtois, who diligently and with great efficiency has played the role of organizer of the event since 1999, and Pascal Nouet, which will continue in the role of Chair from 2015 onwards. So far, first of all the Editor conveys special thanks to Bernard for his continuous and valuable efforts for the past years and good luck to Pascal for the future and successful organization of the DTIP Symposium. Last, but not least, I would like to thank Prof. Yoshio Mita, from the University of Tokyo, Japan, for helping me as a Co-Chair in the CAD conference organization. Technical areas covered by the CAD Conference of DTIP 2014, from which the papers belonging to this special issue have been selected, span from DC to RF applications including technological efforts, mechanical nonlinear properties and nano-characterization of the exploited device configurations. In detail: The first paper: ‘‘Real-Time Characterization of Dielectric Charging in Contactless Capacitive MEMS’’, by Manuel Dominguez-Pumar et al., presents a new method to characterize the dynamics of the charge trapped in the dielectric layer of contactless microelectromechanical systems (MEMS). For sampled-time systems, this allows knowing the state of the net charge at each sampling time without distorting the measurement. The second paper ‘‘Analysis of the adhesion effect in RF-MEMS switches using atomic force microscope’’, by Corina Birleanu and Marius Pustan, is an investigation of the adhesion effect on the mechanical response of MEMS components for RF switch application by using an atomic force microscope (AFM). The occurrence and strength of adhesion effects in MEMS devices depend on a variety of environmental, geometrical and operational parameters, carefully discussed in this contribution. The third paper ‘‘Resonant Behavior Study of PZT Sensor Partially Immersed in Liquid Using PSO Method: Modeling and Experiment’’, by Mahnaz Shamshirsaz and Mohammad Maroufi, is an analysis of resonant piezoelectric-excited millimeter-sized cantilevers (PEMCs) in applications such as liquid level and density sensing. In this work, a PEMC is designed and fabricated to be used as a liquid level sensing platform. An analytical model is developed and applied to evaluate the behavior of this device with respect to different tip immersion depths. The fourth paper ‘‘Analysis and Design of an Electrostatic MEMS Microphone using the PolyMUMPs Process’’, by Owen Casha et al., is the analysis and design of an electrostatic MEMS microphone using the PolyMUMPs process with an additional back-etch processing step. Circular and square (simply supported and clamped) diaphragm designs are considered and analyzed, with the R. Marcelli (&) Institute for Microelectronics and Microsystems (CNR-IMM Roma), National Research Council of Italy, Via del Fosso del Cavaliere, 100 00133 Rome, Italy e-mail: Romolo.Marcelli@cnr.it

Magneto-optic interactions between guided optical waves and nonlinear magnetostatic forward volume waves are studied. For the discussed configuration, when the rf input power reaches 33 dBm and the frequency is lower than 4.2 GHz, the power level of the magnetostatic forward volume wave exceeds the power threshold of the four-magnon process, and the nonlinear magneto-optic dynamic characteristics due to the magnetostatic forward volume wave instability are predicted. The theoretical pattern is supported by experimental results on the magneto-optic mode conversion.