The liquid lens based on MEMS technology can be an appropriate solution to improve the imaging capability of a capsule endoscope because it can be realized small enough and also consume negligible power. In this paper, a cylinder-type liquid lens was designed to minimize the dead area and then fabricated with MEMS technology combining the silicon thin-film process and the wafer bonding process where the multiple dielectric layer of Teflon, silicon nitride and thermal oxide was formed on the cylinder wall. The focal length of the lens module including the fabricated liquid lens was changed reproducibly as a function of the applied voltage. With the change of 30V in the applied bias, the focal length of the constructed lens module could be tuned in the range of about 42cm. The fabricated liquid lens was also proven to be small enough to be adopted in the capsule endoscope, which means the liquid lens can be utilized for the imaging capability improvement of the capsule endoscope.

High k dielectric thick films, consisting of BaTiO3, a low softening glass and fluoride compounds, were studied to apply them as potential low temperature N2-fireable capacitors on commercially-available Cu foils. Different additive combinations of LiF, ZnF2 and BaF2 were specifically compared in terms of dielectric constant, dielectric loss and Curie temperature (Tc) for the purpose of optimizing dielectric performance. The thick film consisting of 95BaTiO3-1.5LiF-1.5ZnF2-2 bismuth borosilicate glass exhibited the best performance, i.e., a dielectric constant of 2,382 and a dissipation factor of 0.021 at Tc of 27°C at the firing temperature of 950°C. This result can be regarded as one of the best performance, compared to literature reported on embedded capacitors in Cu-PCB applications. No apparent Cu-diffusion was detected across the Cu-thick film-Cu foil structure.

In this work, a simple, fast and repeatable technique is proposed for tunable integrated thin film material characterizations. The technique does not depend on the type of material development method or special thin film processing. Moreover, additional structures or calibrations are not required. The proposed method can be used to determine the loss of a thin film material using radio frequency capacitance measurements in both parallel plate and interdigital topologies. An analytical formulation is given for the computation of the film loss based on its measured input impedance which is extracted from the measured scattering parameters. This technique is used for barium strontium titanate (BST) thin film material characterizations.

Ultrasonic consolidation (UC) uses high frequency (20-40KHz) mechanical vibrations to produce a solid-state metallurgical bond (weld) between metal foils. UC as a novel layered manufacturing technique is used in this research to embed reinforcing members such as silicon carbide fibers into the aluminium alloy 6061's matrices. It is known that UC induce volume and surface effect in the material it is acting on. Both effects are employed in embedding active/passive elements in the metal matrix. Whilst the process and the two effects are used and identified at macro level, what is happening at micro level is unknown and hardly studied. In this research we are investigating the phenomena occurring in the microstructure of the parts during UC process to obtain better understanding about how and why the process works.

In this research, high-resolution electron backscatter diffraction is used to study the effects of the UC process on the evolution of microstructure in AA6061 with and without fibre elements.

The inverse pole figures (IPF), pole figures (PF) and the correlated misorientation angle distribution of the mentioned samples are obtained. The characteristics of the crystallographic orientation, the grain structure and the grain boundary are analysed to find the effect of ultrasonic vibration and embedding fibre on the microstructure and texture of the bond. The ultrasonic vibration will lead to exceptional refinement of grains to a micron level along the bond area and affect the crystallographic orientation. Additional plastic flow occurs around the fibre which leads to the fibre embedding.

The present letter describes a reliability study of the micro-electromechanical system fabrication with a photoresist layer used as sacrificial layer with an aluminum beam deposited by means of RF sputtering method. This work reports changes of the roughness and planarity of the sacrificial layer beneath the aluminum film following the sputtering deposition. Such changes may be attributed to the alteration of the photoresist properties due principally to the outgassing of hydrogen by decomposition of C-H bonds under argon plasma. A safe deposition parameters area was identified where the photoresist layer keeps its properties and may be used as sacrificial layer.

Self-sensing and interfacial evaluation were investigated with different dispersion solvents for single carbon fiber/carbon nanotube (CNT)-epoxy composites by electro-micromechanical technique and acoustic emission (AE) under loading/subsequent unloading. Optimized dispersion procedure was set up to obtain improved mechanical and electrical properties. Apparent modulus and electrical contact resistivity for CNT-epoxy composites were correlated with different dispersion solvents for CNT. CNT-epoxy composites using good dispersion solvent showed higher apparent modulus because of better stress transferring effect due to relatively uniform dispersion of CNT in epoxy and enhanced interfacial adhesion between CNT and epoxy matrix. However, good solvent showed high apparent modulus but low thermodynamic work of adhesion, Wa for single carbon microfiber/CNT-epoxy composite. It is because hydrophobic high advanced contact angle was shown in good solvent, which can not be compatible with carbon microfiber well. Damage sensing was also detected simultaneously by AE combined with electrical resistance measurement. Electrical resistivity increased stepwise with progressing fiber fracture due to the maintaining numerous electrical contact by CNT.

The microwave tunable capability and its related material optimization of (Ba,Sr)TiO3 thin films in the parallel-plate capacitor form is discussed in terms of the dependence of barium concentration, acceptor doping, and in-plane film stress, based on the present broadband microwave characterization technique under various bias fields. The barium-content dependence indicates the tradeoff between tunability and dielectric loss, and the notable field-induced loss in SrTiO3 is confirmed as an intrinsic quasi-Debye contribution. The Mg dopant incorporated into a perovskite lattice shows almost no effectiveness on tunable device performance, except for enhanced insulation as an electron acceptor, while the low bias-field dependence of the dielectric loss suggests the possibility of the partial occupation of the alkaline-earth-ion site by Mg. The reduction of in-plane thermal stress controlled by the pressure during sputtering deposition leads to higher permittivity and tunability while degrading the film crystallinity by ion bombardment. The low-frequency loss tends to increase with crystal damage; however, the microwave loss remains unchanged, revealing the applicability of sputtering stress control to real microwave devices. In addition, we demonstrate the operation of an analog phase shifter using parallel-plate ferroelectric tunable capacitors and its application to a phased array antenna monolithically integrated on a silicon substrate.

This paper will first address the piezoelectric material characterization using a capacitance measurement technique. An original simple and efficient technique for the determination of the d33 piezoelectric coefficient of lead zirconate titanate thin films is described. Classical capacitor plate theory and piezoelectric material analysis are used to calculate the capacitance variation in lead zirconate titanate film, enabling piezo-electric coefficient to be determined. The technique outlined here avoids the use of mechanical/optical apparatus that may require heavy preparation of sample substrate geometry. Then, this work also treats design and fabrication issues associated with innovative tunable front-end components which combine two different ceramic technologies, namely multilayer ceramic circuit boards (low temperature cofired ceramics or LTCC) and piezoelectric actuator technology within a single device.

Fabrication of truly flexible optoelectronic devices, such as flexible displays and flexible photovoltaics, is highly dependent on the mechanical integrity of individual thin inorganic/organic hybrid device components. A common feature of almost all thin composite film components for flexible optoelectronic applications is indium tin oxide (ITO) coated on polyester.

The mechanical mismatch of the ITO ceramic coating, a few tens of nm thick, with the polyester, either polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), 125 ìm thick, causes the flexible functional structure to fail at moderately low strains under various, externally applied, stress states. It is therefore important to assess the mechanical integrity of such hybrid systems experimentally. We report on the electromechanical behavior of such hybrid systems.

Pb(Zr0.53, Ti0.47)O3 (PZT) thin films are potentially interesting as piezoelectric layer in bulk acoustic wave (BAW) resonators. We investigated properties and performance of {111} and {100} textured, dense films deposited by sol-gel techniques in the frequency range of 1 to 2 GHz. The resonators were fabricated on Si wafers using deep silicon etching to create a membrane structure and using platinum as top and bottom electrodes. The best response of the resonators was observed at a bias voltage of −15kV/cm with values of around 10% for the coupling constant and around 50 for the quality factor. This voltage corresponds to the maximal value of the piezoelectric constant d33 and minimal value of the dielectric permittivity measured as a function of the electric field. Resonance and antiresonance frequencies were strongly influenced by a bias voltage, showing a hysteretic behaviour as expected for ferroelectrics. Both of these frequencies shifted in the same direction. As a consequence, the dc voltage can be potentially used to shift the whole band of a filter. In unipolar operation, the coupling constant could be varied from 6 to 10 %. Materials parameters were extracted from the admittance as a function of frequency. Dielectric, piezoelectric and elastic properties of textured PZT films are reported and compared to direct (low frequency) measurements and to literature values. It was found that PZT thin films have lower stiffness than the one of PZT bulk ceramics and it was observed that {111}-textured films are stiffer than {100}-textured films.

The paper presents a systematic investigation of dielectric charging in low temperature silicon nitride for RF-MEMS capacitive switches. The investigation takes includes both the effect of dielectric film thickness as well as the effect of metal contacts. The investigation demonstrates that the charging process is asymmetric. It is shown that the amount of stored charge depends significantly on the dielectric film thickness, which is caused from the contribution of the space charge polarization mechanism. Finally, the results are compared with those of higher temperature silicon nitride.

In this work stacked boron doped poly-crystalline Silicon-Germanium (poly-SiGe) layers, which can be applied as structural MEMS layers, were studied. A standard 1 µm base layer, deposited at 480 ºC chuck temperature, is stacked until the required thickness (e.g. 10 x for a 10 µm thick layer). This 1 µm base layer consists of a PECVD seed layer (+/− 75 nm), a CVD crystallization layer (+/− 135 nm) and a PECVD layer to achieve the required thickness with a high growth-rate. The top part of this PECVD layer can optionally be used for optimizing the stress gradient by a stress compensation layer. This approach resulted in 4 µm thick poly-SiGe MEMS structural layers with low tensile stress (50 MPa), low resistivity (2 mΩcm) and a low strain gradient (< 1*10−5/µm).

This paper first discusses the reasons for choosing CMOS-MEMS integration, in particular integration by poly-SiGe processing above CMOS. Next the current state-of-the-art for poly-SiGe MEMS integration and the needs for the future will be addressed. Market trends are translated into two roadmaps for MEMS integration. The first roadmap is based on existing poly-SiGe deposition processes at 400 − 450 ºC. The second roadmap explores processing techniques to lower the thermal budget and widen the application field of MEMS integration by using processing techniques such as metal-induced crystallization, laser annealing or self-assembly.

Polyimides thin films, which are the most commonly used group of sensing materials for capacitive humidity sensors, were cured locally using MEMS microhotplates. The polyimide locally cured at temperature over 350 °C for 1 hour was fully cured. There were no significant differences in the polyimide thin films between cured in convection ovens and locally cured on microhotplate. The locally cured polyimide humidity sensor showed a linearity of 0.9995, a sensitivity of 0.766pF/%RH, a hysteresis of 0.6%RH, and a time response of 3 s. These results show the possibility of locally-cured polyimide films as high speed, high-sensitivity humidity sensors.

The convergence paradigm of today, which can be characterized as multi function and high effectiveness, strongly requires an integration of RF/analog function and high-speed digital function into a single IC or package. System on Package (SOP) is a promising technology for system integration in order to meet these current trends and requirements. A passive embedded substrate is one of the most critical issues to achieve small-size and high-functional devices and modules with high integration density and deign flexibility for wireless communications.

This paper will describe integration approach for passive embedded substrate for RF applications. With the several examples such as multi-band front end module and passive/active integrated modules, the advantages of the integration using passive embedded substrates will be described with some design considerations.

The ablation of strontium-doped lead zirconate titanate (PSZT) and lanthanum-doped lead zirconate titanate (PLZT) films has been examined using a 5 ns pulsed excimer laser. Individual squares were patterned with sides in the range of 10-30 µm using single and multiple pulses. The depth of ablation in PLZT films was higher at all fluences than in PSZT films. The morphology of the etched surfaces has comprised the formation of globules which had diameters of 200-250 nm in PLZT and 1400-1600 nm in PSZT films. The diameter of the globules has been shown to increase with fluence until reaching an approximately constant size at >20 J/cm2 in both types of film. The composition of the films following ablation has been analyzed using x-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray (EDX) spectroscopy.