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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.

We develop shunt capacitive RF MEMS switches in III-V technology making use of materials which can be alternative to the ones commonly used, in order to overcome some technological constraints concerning the RF MEMS reliability. Specifically, we evaluate the potential of tantalum nitride (TaN) and tantalum pentoxide (Ta 2 O 5 ) to be used for the switches actuation pads and dielectric layers, respectively. To this scope, a compositional, structural and electrical characterization of TaN and Ta 2 O 5 films as a function of the deposition parameters, such as the substrate temperature and the sputtering mixture composition, is performed. The realized switches show good 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. A comparison between the measured S-parameter values and the results of a circuit simulation is also presented and discussed, providing useful information on the operation of the fabricated switches.

In this paper, two matched microstrip line configurations for the excitation of magnetostatic wave resonators have been studied for optimizing the performances of a Magnetostatic Wave (MSW) Straight Edge Resonator (SER). The first transducer was designed for a band-stop and the second one for a band-pass resonator, both suspended on a silicon micromachined membrane obtained by means of wet anisotropic etching. It has been previously observed that the insertion losses of microstrip lines on silicon membrane for band-stop and band-pass MSW SERs are improved with respect to the same microstrip line structures realized on a silicon bulk substrate. For that reason the modelling of the microstrip lines has been optimized in view of their application in SER devices. The Microwave Office program, a powerful tool for the design of microwave planar devices, has been used. The theoretical S-parameters have been obtained and optimized by changing the geometry in the design of the transmission lines.

Two band-stop SERs (resonator A and resonator B) on silicon membrane were obtained and characterized. The frequency tunability domain of these resonators was between 3 GHz and 9.5 GHz ca. obtained by changing the dc magnetic bias field between H appl = 0.02 T and H appl = 0.34 T. The measurements of the S 21 parameter demonstrate a suppression of more than 20 dB of the high order modes, showing a good selectivity of this kind of resonator. The rejection ratio was better than -20 dB in the frequency domain from f = 3 GHz to f = 9.5 GHz for the resonator A and better than -20 dB between f = 4.2 GHz and f = 9.5 GHz for the resonator B. These results demonstrate the possibility to obtain microwave band-stop resonators supported on silicon membrane with high isolation and rejection ratios. Keywords: Microwave resonators, YIG monocristalline film, Silicon membrane, Micromachining 1. INTRODUCTION Microwave sources and filters having broadband characteristics and high spectral purity are generally required for modern satellite and ground communication systems. Dielectric oscillators, not electronically tunable but characterized by high quality factors Q (about 10000), and varactor oscillators, tunable but having lower Q's (about 1000), have been extensively studied and are currently used depending on the preferred performance (tunability or quality factor). Magnetostatic wave (MSW) technology is well known for providing frequency tunable filters and oscillators for linear and non-linear microwave signal processing [1 - 4]. Planar microwave oscillators and filters based on MSW excitation in epitaxial garnet films propose themselves as a natural improvement of the existing devices, because they exhibit reasonable Q

This paper presents the technological processes developed in order to obtain high quality 1.5micrometers membranes on high resistivity (100) and (111) oriented silicon. To emphasize the outstanding characteristics of the membrane supported elements, coplanar meander-line, 'S'-line and square spiral inductors, as well as interdigitated capacitors were designed and manufactured both on dielectric membranes and on bulk SI GaAs substrates, and their equivalent circuit was developed, too. An improvement of the measured resonant frequencies by a factor of 1.7 to 1.8 was noticed. Equivalent circuits, able to simulate the behavior of the coplanar elements up to twice their resonance frequencies, were developed. The paper brings into relief, quantitatively, the superiority of the membrane supported microwave planar lumped elements.

The aim of this paper is to determine an optimum nonselective etching solution in order to manufacture an as thin as possible, uniform and high quality GaAs membrane. Three different etching systems in various proportions of the components were analyzed. A high quality 10 micrometer thin GaAs membrane was obtained using the [1(H3PO4)]: [1(CH3OH)]: [3(H2O2)] etching solution. The micromachined GaAs membranes are manufactured to be used as support for microwave circuits as well as in high temperature sensor applications.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, the design of a new magneto-optical device based on the resonant interaction between magnetostatic and light waves in a two-port band-pass filter is proposed for potential applications in optical modulation, and its performances are theoretically predicted. The advantages of a microwave resonating filter with respect to delay lines for the magneto-optical interaction are a more compact geometry, owing to the reduced dimensions, an increased optical modes conversion efficiency and the low microwave input power. As a peculiar result on the configuration proposed, the device allows for a possible interaction between light and microwave signals when surface magnetostatic waves are excited.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Diffraction of guided light by magnetostatic waves generated in ferri.magnetic garnets is emerging as a promising new technology for optical signal processing in integrated optics format. Here the design and fabrication criteria for producing suitable single-mode waveguides in an YIG-GGG structure are investigated. A complete analysis of the optical propagation in multilayer waveguides is presented, and the need of further experimental investigations of LPE-grown doped YIG layers is discussed.