Sabrina Colpo
fondazione bruno kessler
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Publication
Featured researches published by Sabrina Colpo.
ieee eurocon | 2009
Jacopo Iannacci; Flavio Giacomozzi; Sabrina Colpo; Benno Margesin; M. Bartek
In this paper we present a power attenuator for RF (RadioFrequency) and microwave signals entirely designed in MEMS (MicroElectroMechanical-System) technology. It is fabricated in the RF-MEMS technology available at Fondazione Bruno Kessler (FBK) based on a surface micromachining process. The network is realized in a low-cost manufacturing process and its dimensions are significantly compact compared to traditional implementations of RF power attenuators. More interestingly, employment of MEMS technology for such architecture enables a very large reconfigurability, making the network compatible with different standards and usable in several wireless communication systems. Electromechanical and RF behaviour of the discussed network are simulated and compared against experimental results collected by the first fabricated samples. RF measured performances are rather promising in spite a technology issue occurred during the fabrication deteriorating the attenuator low-frequency characteristic. RF modelling of such issue (already fixed in the batches being currently fabricated) is shown and discussed through this paper.
international semiconductor conference | 2011
Flavio Giacomozzi; V. Mulloni; Sabrina Colpo; Jacopo Iannacci; Benno Margesin; Alessandro Faes
The paper reports about the technology platform for the fabrication of RF-MEMS devices developed at FBK. The most important process features, requirements and possible applications are presented and described. The basic fabrication process, together with some of the more important process variations and its capabilities are reported. Finally, some examples of produced devices and their performances are briefly presented.
Applied Physics Express | 2011
A. Picciotto; D. Margarone; Michele Crivellari; P. Bellutti; Sabrina Colpo; L. Torrisi; J. Krása; Andriy Velhyan; J. Ullschmied
An ad hoc microfabrication technique was employed for the optimization of thin hydrogenated silicon membranes for the first experimental application in the field of laser-driven proton acceleration. The tetra methyl ammonium hydroxide wet etching and further microfabrication processes allowed the optimization of the target structure and geometry. Samples were doped in a H2 environment during an annealing process at 420 ?C in order to increase the hydrogen concentration in the silicon matrix. This solution enabled the production of high-current (about 100 mA at 1 m from the source) and multi-MeV proton beams.
IEEE Transactions on Microwave Theory and Techniques | 2011
Marco Antonio Llamas; David Girbau; Miquel Ribo; L. Pradell; Flavio Giacomozzi; Sabrina Colpo
In this paper, a new compact broadband uniplanar 180° phase switch, based on an air-bridged coplanar-waveguide (CPW) cross loaded with two capacitive-contact microelectromechancial systems (MEMS) switches in opposed (on/off) states, is presented. The two phase-switch states (0°/180°) are defined by actuating the MEMS switches from on/off to off/on. The asymmetry in the states of the MEMS switches results in a complex multimodal interaction between the two fundamental even and odd CPW modes at the air-bridged cross. Using the multimodal theory, the phase switch is analyzed, its frequency-in dependent 180°-phase-shift properties are proven, and a set of design equations for perfect port matching are derived. A multi modal circuit model for the phase switch is then presented, and design equations and conditions for compact phase switches are derived. Finally, a very compact phase switch is designed and fabricated using an eight-mask surface micromachining process, featuring a measured phase shift of 180° ± 1.8° in a very wide frequency range (1-30 GHz) and an insertion loss better than 2.1 dB in the design band (10-20 GHz). Experimental results are in very good agreement with electromagnetic and multimodal circuit simulations, thus validating the proposed approach and design procedure.
international semiconductor conference | 2012
Abdul Qader Ahsan Qureshi; Sabrina Colpo; Dan Vasilache; Stefano Girardi; Paolo Conci; Benno Margesin
The paper presents preliminary results on Au-Au and Ag-Ag thermocompression bonding at low temperature. For both materials, sample structures have been prepared and different bonding conditions experimented. Results are compared in order to evaluate Au and Ag bond strength and to establish the optimum parameters. Shear tests were performed to quantify the bond strength and after that SEM was employed to examine the bonded joints. Bond strength of Ag-Ag compare to Au-Au (at 300°C and under the pressure of 0.196 MPa) seems more promising.
IEEE\/ASME Journal of Microelectromechanical Systems | 2014
Jasmina Casals-Terré; Marco Antonio Llamas; David Girbau; L. Pradell; A. Lazaro; Flavio Giacomozzi; Sabrina Colpo
In this paper, the dynamic behavior of electrostatically actuated radio frequency-microelectromechanical system (RF-MEMS) switches is analyzed using energy considerations. An analytical model for bridge-type RF-MEMS switches is proposed and the time evolution of the system total energy is calculated numerically. Switch actuation, release times, and damped release response are derived from energy analysis with focus on the effect of increasing the actuation voltage on the RF-MEMS dynamic behavior. The dynamic and RF characteristics of different RFMEMS ohmic-contact switches have been measured using an experimental set-up based on microwave instrumentation. The measured results show a good agreement with simulations, thus validating the proposed analytical model. It is shown (theoretically and experimentally) that the damped release response increases the effective time to reach the RF/microwave OFF-state switch isolation (up to three natural periods of the mechanical system).
Smart Sensors, Actuators, and MEMS V | 2011
Dan Vasilache; Sabrina Colpo; Flavio Giacomozzi; Sabina Ronchin; Abdul Qader Ahsan Qureshi; Benno Margesin
This paper reports a method on the manufacturing of through wafer via holes in silicon with tapered walls by Deep Reactive Ion Etching (DRIE) using the opportunity to change the isotropy in the DRIE equipments during processing. By using consecutively anisotropic and isotropic etching steps it is possible to enlarge the dimension of via holes on one side of the wafer, while on the other side dimension is set by the initial etching window. The method was used for two etching windows sizes (100μm and 20μm respectively) on 200μm and 300μm thick wafers. The aim was to manufacture tapered walls via having a good control over the walls angle. Different Bosch process recipes providing different walls roughness were used. Via holes with tapered walls (2° to 22°) were manufactured using this method. An angle deviation smaller than 10% of the manufactured via holes along the wafers was observed.
international semiconductor conference | 2010
Dan Vasilache; Sabrina Colpo; S. Ronchin; Flavio Giacomozzi; Benno Margesin
A new process for through-wafer interconnects was studied by our group. This new process was developed to facilitate metallised through wafer via holes manufacturing. V-shape profile can contribute to an easier metallisation process and better adhesion. Manufacturing process use the possibility to change the isotropy in the Deep Reactive Ion Etching (DRIE) equipments from anisotropic to completely isotropic. Two slightly different processes were used in order optimize the technology and to see the changes introduced by isotropic/anisotropic processes sequence.
Smart Sensors, Actuators, and MEMS VI | 2013
A. Q. A. Qureshi; L. Pelliccia; Sabrina Colpo; Jacopo Iannacci; P. Farinelli; Benno Margesin
This paper presents the design and fabrication of a 2nd order L/S band filter used as a test vehicle for the development of a fabrication technology for cavity microwave filters based on micromachining in order to preliminary explore all the technological constraints on a simpler structure. The multilayered 2nd order pseudo-elliptic L/S band filter is based on λ/4 TEM mode resonators which are patterned on a dielectric layer. For convenience 500 μm thick Si wafers have been used even if this limits the simulated Q factor of the 2nd order L/S band filter to about 200. The test structures presented here amount to the more sophisticated 4th order filters in an extended technological concept (i.e. 1500 μm thick Si wafer and two additional modules) but still based on similar resonating elements aiming to replace the existing bulky metallic waveguide filters installed in many satellite transceivers. A five mask fabrication process is employed for the realization of the elements of said filter which is based on three modules. Module A and B are fabricated on the same wafer while module C which served as ground is fabricated on a separate wafer. A 2 μm high sealing ring is etched on the back of module A and B by DRIE (Deep Reactive Ion Etching) while cavities and TSVs (Through Silicon Vias) are etched by TMAH (TetraMethylAmmonium Hydroxide). The surface mounting compatibility of the filter is obtained by adopting vertical via holes to connect the external feeding lines (e.g. microstrip or coplanar) with the filter resonators. Such a transition separates the input/output from the filter input/output coupling mechanism. The final wafers are diced and specimens are vertically stacked and bonded through thermocompression bonding. The overall filter dimensions are 48x20x1.5 mm3.
Smart Sensors, Actuators, and MEMS V | 2011
V. Mulloni; Jacopo Iannacci; R. Bartali; V. Micheli; Sabrina Colpo; N. Laidani; Benno Margesin
In RF-MEMS switches many reliability issues are related to the metal contacts in the switching area. The characteristics of this contact influence not only contact resistance and insertion loss, but also the most relevant switch failure mechanisms that are wear of ohmic contact, adhesion and stiction. Gold is widely used for this purpose because of its good conductivity and chemical inertness, but is a soft metal, and the development of hard contact materials with low resistivity is of great interest for RF-MEMS switch reliability. It is possible to increase the contact hardness preserving the convenient gold properties alternating gold layers with thin layers of different metals. The material becomes harder not only by simple alloying but also by the presence of interfaces which act as barriers for mechanical dislocation migration. A detailed study of mechanical, electrical and morphological properties of gold-chromium, gold-platinum and gold-palladium multilayers is presented and discussed. It is found that the annealing treatments are important for tuning hardness values, and a careful choice of the alloying metal is essential when the material is inserted in a real switch fabrication cycle, because hardness improvements can vanish during oxygen plasma treatments usually involved in RF-switches fabrication. Platinum is the only metal tested that is unaffected by oxidation, and also modifies the chromium adhesion layer diffusion on the contact surface.