The objective of this paper is to present the compatibilization between a standard CMOS on bulk silicon process and the fabrication of nanoelectromechanical systems using Silicon On Insulator (SOI) wafers as substrate. This compatibilization is required as first step to fabricate a very high sensitive mass sensor based on a resonant cantilever with nanometer dimensions using the crystal silicon COI layer as the structural layer. The cantilever is driven electrostatically to its resonance frequency by an electrode placed parallel to the cantilever. A capacitive readout is performed. To achieve very high resolution, very small dimensions of the cantilever (nanometer range) are needed. For this reason, the control and excitation circuitry has to be integrated on the same substrate than the cantilever. Prior to the development of this sensor, it is necessary to develop a substrate able to be used first to integrate a standard CMOS circuit and afterwards to fabricate the nano-resonator. Starting from a SOI wafer and using very simple processes, the SOI silicon layer is removed, except from the areas in which nano-structures will be fabricated; obtaining a silicon substrate with islands with a SOI structure. The CMOS circuitry will be integrated on the bulk silicon region, while the remainder SOI region will be used for the nanoresonator. The silicon oxide of this SOI region is used as insulator; and as sacrificial layer, etched to release the cantilever from the substrate. To assure the cover of the different CMOS layers over the step of the islands, it is essential to avoid very sharp steps.

In this paper, we have presented the novel method of fabricating multiplayer-stacked SOI (MultiBond). Tight thickness and TTV control was achieved, which allowed the bonding of multiple layers of SOI of up to 4-layer stacks. Investigation of the stress showed that having the handle wafer oxidized at the back significantly reduced the stress by compensating for the buried oxide layers. Study was also made on the effect of incorporating different buried layers on the minority carrier lifetime in the SOI layer. Here, a thermally grown buried oxide layer gave the highest carrier lifetime. We have also investigated the surface defect density with different buried layer materials, and found that samples with tungsten silicide as a buried layer had the highest defect density, while an LPCVD TEOS oxide buried layer showed the lowest level.

Presently, there is a growing demand from the industry for microprocessing of materials. For applications in microsystems technology and biotechnology it is particularly necessary to produce structures with dimensions down to the micrometer scale. This refers especially to materials that can not or not in a sufficiently quality be processed by conventional methods of silicon technologies. In order to fulfil the industrial demands we have investigated the structuring of anodic bondable PYREX glass and of polymers by means of laser microprocessing using the excimer laser mask projection technique (193 nm wavelength, 10 ns pulse duration, 8 mJ pulse energy, 500 Hz repetition rate). In our paper we will show the dependence of the obtained quality especially the roughness of the generated surfaces on the processing parameters. The possibilities of our technology including the creation of holes, channels and three dimensional microstructures will be presented too. Single structures e.g. bridges and grooves are attainable with widths of 10 micrometers and below. Some of the drilled holes (diameter about 50 µm) have been successfully filled inside with aluminium by a laser assisted CVD process.

In this study, stereolithography of PZT films or composites has been successfully carried out. With regard to the PZT suspensions formulation, the process was modified to allow the deposition of films with thickness ranging between 8 to 40 μm. 1-3 and 0-3 piezocomposites as well as other highly loaded structures (maximum 45 % in volume) have been elaborated. Moreover, PZT thick films have been deposited on metallic substrates and silicon wafers. After sintering, crack-free PZT films with thickness ranging between 12 to hundreds of microns have been metallized and polarized. The properties of these microstructures have been studied with permittivity and piezoelectric coefficients measurements. Experiments have shown that the piezoelectric properties of PZT ceramics fabricated by stereolithography are promising (d₃₃ up to 200 pC/N and g₃₃ greater than 30×10^-3 Vm/N), which implies that such structures could be integrated in MEMS for microactuators or sensors applications. Finally, simultaneous fabrications by conventional stereolithography of polymer micropumps and their related piezoelectric transducers have been tested. The upper polymer member of the micropump is 100 μm thick and the inner diameter of the pump is 5 mm. Researches are in progress to improve the micropump flow rate and to manufacture a drop-on-demand inkjet device.

One of the problems faced in the development of micro-gripper is that the actuation displacement or force is too small. In this study, it is aimed to solve this problem with application of shape memory and compliant mechanisms. TiNi film based micro-gripper with compliant structure was design, simulated and fabricated. Some important issues regarding to the preparation of high performance shape memory TiNi films using sputtering methods were discussed.

Hydrogels composed of poly(vinyl alcohol) (PVA) and poly(N-isopropylacrylamide) (PNIPAAm) was prepared by the sequential-interpenetrating polymer network (IPN) method. The equilibrium swelling ratio and bending behavior under electric fields of the IPN hydrogel were measured in aqueous NaCl solution. The IPN exhibited a high equilibrium swelling ratio, in the range 280~380%. When the IPN in aqueous NaCl solution is subjected to an electric field, the IPN showed significant and quick bending toward the cathode. The IPN hydrogel also showed stepwise bending behavior depending on the electric stimulus. In addition, ionic conductivity of the IPN hydrogel was measured using dielectric analysis (DEA). The ionic conductive behavior of IPN hydrogel follows the Arrhenius equation. The conductivity of IPN hydrogel and the activation energy for the form of the IPN were 1.68 ×10^-5 S/cm at 36 °C and 61.0 kJ/mol, respectively.

HAPEX is an artificial bone analogue composite based on hydroxyapatite and polyethylene, which can be applied for growth of bone cells. Due to its biocompatibility and favourable mechanical properties, HAPEX is used for orthopaedic implants like tympanic (middle ear) bones. The morphology of HAPEX surfaces is of high interest and it is believed that surface structuring on a micron scale might improve the growth conditions for bone cells. A new and simple approach for the microstructuring of HAPEX surfaces has been investigated using LIGA technique. LIGA is a combination of several processes, in particular lithography, electroplating and forming/moulding. For HAPEX surface structuring, arrays of dots, grids and lines with typical lateral dimension ranging from 5 μm to 50 μm were created on a chromium photomask and the patterns were transferred into thick SU-8 photoresist (structure height > 10 μm) by UV lithography. Subsequently, the SU-8 structures served as moulds for electroplating nickel on Si wafers and nickel substrates. The final nickel microstructures were used as embossing master for the HAPEX material. Embossing was carried out using a conventional press (> 500 hPa) with the facility to heat the master and the HAPEX. The temperature ranged from ambient to a few degrees above glass transition temperature (T_g) of HAPEX. The paper will include details of the fabrication process and process tolerances in lateral and vertical directions. Data obtained are correlated to the temperature used during embossing.

An improved method is described for the sol-gel preparation of PZT ceramics in the perovskite structure. This method uses acetic acid as a solvent. Details are reported for the modified sol-gel processing route and heat-treatment conditions. By using this method it is possible to prepare single perovskite material with improved properties. The deleterious effect of additional phases is attributed to Pb loss from the surface during thermal processing. The density of the PZT pellets is observed to decrease as the sintering time increases. A ninety-seven percent theoretical density is obtained for samples sintered at 950°C for two hours. The dielectric properties of the PZT are measured and compared with unmodified sol-gel.

Our main objective in this work has been to develop a comunication system applicable between sensors and actuators and the data processing circuitry inside the microsystem in order to develop a flexible and modular architecture. This communication system is based on the use of a dedicated sensor bus composed by only two wires (a bidirectional data line and a clock line for sincronization). The basic philosophy of this development has been to create an IP model with VHDL for the bus driver that can be added to the sensor or the actuator to create an smart device that could be easily plugged with the other componets of the microsystem architecture. This methodology can be applied to a high integrated microsystem based on an extensively use of microelectronics technologies (ASICs, SoCs & MCMs). The reduced number of wires is an extraordinary advatage because produce a minimal interconnection between all the components and as a consequence the size of the microinstrument becomes smaller. The second aspect that we have considered in this development has been to reach a communication protocol that permits to built-up a very simple but robust bus driver interface that minimize the circuit overhead. This interconnection system has been applied to biomedical and aerospatial microsystems applications.

The desirable electrical properties of InO_x thin films and their response towards oxidizing gases has promoted InO_x to be recognized as a promising material for gas sensors. In this study, InO_x films in the thickness range of 10-1000 nm were deposited onto Corning 7059 glass substrates by dc magnetron sputtering. Their structural, electrical, and O₃ and NO₂ sensing properties were analyzed. Structural investigations carried out by XRD and AFM showed a strong correlation between crystallinity, surface topology and gas sensitivity. Moreover, the electrical conductivity exhibited a change of over six orders of magnitude during the processes of photoreduction and oxidation. The films deposited on alumina transducers were calibrated towards O₃ and NO₂ at temperatures from 50-300 °C. The sensors show promising characteristics as they exhibited reproducible and stable responses. The 50 nm thin film had a response of over 10 towards 50 ppb of ozone operating at 50°C, while the 20 nm film had a response of over 22 towards 0.1 ppm of NO₂ at 100°C.

In 1985 Gerd Binnig and Calvin F. Quate from Stanford and Christopher Gerber from IBM (Zurich) designed the Atomic Force Microscope (AFM), since then a big interest arose around one of its main components; micromachined cantilevers. During all these years, authors have employed these tiny devices to sense multiple physical and chemical parameters through diverse transduction principles. Micromachined cantilevers offer many different transduction mechanisms: force sensing, bimetallic effect, mass loading, medium viscoelasticity, thermogravimetry, stress sensing, and more. Along with all these transduction mechanisms, a great variety of detection methods can be employed with cantilever-based sensors as for example: optical detection, resonance frequency measurement, piezoelectric integrated resistors, etc. The design and fabrication process of a micromachined Silicon capacitive gas sensor are described in this paper. Design and testing of the interface circuitry are also shown with preliminary results.

This study investigates magnetic layer structures suitable for devices measuring mechanical responses such as stress, strain and pressure. The sensors are based either on giant magnetoresistiance (GMR) structures or on magnetic tunneling junctions (MTJ's) both intentionally prepared with highly magnetostrictive free layer materials. Results for magnetostrictive Fe₅₀Co₅₀ materials or amorphous Co- or Fe-based alloys serving as sensing (or “free”) layers are discussed in view of possible applications. In general, gauge factors in the range of 300-600 have been obtained for strain sensors based on MTJ's, whereas gauge factors of 2-4 are typical for metal based thin film, and 40-180 for piezoresistive strain gauges.

Ion-selective field transistors (ISFET) are electronic devices that merge solid-state electronic technology with chemical sensors for being sensitive to the concentration of a particular ion in a solution. However, as it has been reported, their response does not only depend on a single ion but is also affected by several interfering ions found in the solution to be measured. These interfering ions can be considered as a noise and consequently, a post-processing stage that increases the SNR is mandatory. Our work shows how neural network (NN) structures, a kind of statistical learning machines, could be used for this purpose. In particular, we introduce several novel neural learning architectures for ISFET source separation from interfering ions, which employ ISFET models as a prior knowledge. The proposed NNs are grouped in two categories: supervised and unsupervised. The supervised NN is a RBF-like solution that could be used using a single ISFET or with an ISFET array. On the other hand, the unsupervised NN is based on non-linear independent component analysis (ICA) that employs two or more ISFETs. Since the RBF-like NN structure needs many training data pairs for calibration, and this could be a practical problem, a synergistic combination of unsupervised and supervised methods is introduced. The proposed hybrid NN is based on a combination of non-linear ICA and a linear predictor that considerably reduces the number of required samples in order to achieve a good solution. In the final work, several experimental results are included, which demonstrate the interest and viability of the proposed solution. The work is in progress, as a part of the SEWING EU project (contract IST-2000-28084).

The requirements of flow measurement and control in the home-appliances field lead to the need of a measurement system able to monitor the flow and the quality of gas. The integration of a set of sensors with different functionalities on a single chip arises as an advantageous solution. In this paper, the description of the structures and technologies required for the gas, flow and temperature sensor devices is presented prior to the complete description of the process flow for the full on-chip compatibilization. In this sense, semiconductor gas sensors and thermal flow sensors have arisen as the best candidates to address the compatibilization.

A pencil-shaped electrochemical transducer system for analysis or surface modification in nanometer dimension has been developed. High aspect ratio tip structures are shaped combining isotropic and anisotropic deep reactive etch processes to form the body of the transducer. In this way, tips with an aspect ratio higher than 20 and a tip radius of smaller than 50 nm can be achieved. Subsequently, a three-layer system (an isolation layer: silicon nitride, a metal layer: platinum or gold and an isolation layer: silicon nitride) was deposited on the tip structure. Planarization of this structure in combination with a back etch process enables a precise exposure of the buried metal layer down to an electrode dimension of 200 nm on the tip. Electrochemical and impedance spectroscopic characterization showed full electrochemical functionality of the transducer system. Due to the high aspect ratio topography, this probe is particularly suited for Scanning Electrochemical Microscope (SECM) - methodologies. Furthermore this technology promises a feasible production possibility for both probe-arrays and probes on cantilevers.

This paper highlights the current technology development activities of the MEMS Technology Group at JPL. A diverse range of MEMS/NEMS technologies are under development, that are primarily applicable to NASA’s needs in the area of robotic planetary exploration. MEMS/NEMS technologies have obvious advantages for space applications, since they offer the promise of highly capable devices with ultra low mass, size and power consumption. However, the key challenge appears to be in finding efficient means to transition these technologies into “customer” applications. A brief description of this problem is presented along with the Group’s innovative approach to rapidly advance the maturity of technologies via insertion into space missions. Also described are some of the major capabilities of the MEMS Technology Group. A few important examples from among the broad classes of technologies being developed are discussed, these include the “Spider Web Bolometer”, High-Performance Miniature Gyroscopes, an Electron Luminescence X-ray Spectrometer, a MEMS-based “Knudsen” Thermal Transpiration pump, MEMS Inchworm Actuators, and Nanowire-based Biological/Chemical Sensors.

Low temperature wafer bonding is a powerful technique for MEMS/MOEMS devices fabrication and packaging. Among the low temperature processes adhesive bonding focuses a high technological interest. Adhesive wafer bonding is a bonding approach using an intermediate layer for bonding (e.g. glass, polymers, resists, polyimides). The main advantages of this method are: surface planarization, encapsulation of structures on the wafer surface, particle compensation and decrease of annealing temperature after bonding. This paper presents results on adhesive bonding using spin-on glass and Benzocyclobutene (BCB) from Dow Chemicals. The advantages of using adhesive bonding for MEMS applications will be illustrated be presenting a technology of fabricating GaAs-on-Si substrates (up to 150 mm diameter) and results on BCB bonding of Si wafers (200 mm diameter).

Three-dimensional polysilicon microstructures, as cantilevers or bridges, give new opportunities to increase the application field of polycrystalline silicon. Polysilicon devices with new functions can be imagined. Air-gap thin film transistors can be built from polysilicon bridges for example. They use a highly doped polysilicon bridge as gate; the gate insulator is the air or any other ambience. Then, these devices can be used as ambience sensors including chemical or biological sensors. They are very interesting as they are deposited on any substrate. Moreover, their main interest is their full compatibility with the microelectronics technology on glass performed at temperature lower than 600°C and developed first for the flat panel displays addressing. Fully integrated sensing systems are then imaginable. Here we present a low temperature process (< 600 °C) to built air-gap-polysilicon-thin-film-transistor with high mechanical and electrical performance. The transistor-active-layer is made of Low Pressure Chemical Vapor Deposition (LPCVD) undoped polysilicon while the suspended gate is made of LPCVD highly doped polysilicon. Deposition and annealing conditions of the doped polysilicon has first optimized to obtain high mechanical performance for the polysilicon micro-bridges. Hence, an optimal tensile stress to obtain longer bridges has been found. The mechanical stress has been determined from micro-Raman analysis. Then, air-gap transistors with 500 nm thick air-gap as gate insulator have been designed and fabricated. The transistor channel is 7-μm long and 7-μm wide, with a 15-μm long and 10-μm wide bridge. Their subthreshold slope, threshold voltage, and field effect mobility are 0.22 V/dec, 2.4 V and 130 cm²/V.sec respectively. These parameters are comparable to that of the best polysilicon thin film transistors with thin silicon dioxide (100 nm) as gate insulator. Then, these transistors are interesting as electronic devices firstly. Moreover they can be involved in ambience sensors. Indeed, they are checked as oxygen sensor in a preliminary experiment. Transistor characteristics are measured in air ambience, then in oxygen and finally in air. The electrical parameters have shown a considerable dependence on the ambience with an excellent recovering after removing oxygen.

An emerging non-photolithographic technology, soft lithography, is applied with the aim of patterning ferroelectric thin film oxides, in particular sol-gel deposited Lead Zirconate Titanate (PZT). Soft lithography relies on the replication of a patterned master using an elastomeric material and then, using this as a stamp to create micro- and nanometer scale patterns and structures. Following this procedure, a set of masters were fabricated both using photolithographic and Focused Ion Beam (FIB) methods. Masters were replicated using a commercial polymer (PDMS), satisfactorily reproducing the negative of the master’s features down to a limit of 500 nm. The obtained stamps were used to produce patterned self-assembled monolayers (SAMs) of alkanethiols over surfaces of gold, using the technique of microcontact printing (mCP). The patterned SAMs were then employed as a molecular thin resist to create microstructures of gold by wet etching. This is a key step for establishing a new route for the fabrication of ferroelectric thin film capacitors made of Pt/PZT/Au by Reactive Ion Etching (RIE) using the patterned gold features as both mask and top electrode, thus avoiding alignment stages in the fabrication procedure.

In this work we obtain some boundary observability inequalities with Dirichlet boundary conditions on displacement vector and an excat controllability of a coupled electro-mechanical system with coefficients depending on both space and time variables. Let us mention that some results on modeling of such coupled systems have been derived by Senouci-Bereksi and Hoffmann for piezoelectric plates and electrical networks and junctions and Senouci-Bereksi and Lenczner for piezoelectric shells coupled to some active electronic networks under different configurations. Some results on observability and exact controllability for general elastic systems with constant coefficients not depending in time, have been obtained by Alabau and Komornik. To our knowledge this work seems to be new and very interesting for researchers working on smart materials and systems investigations.

Data-storage using near-field optical microscopy is a promising technology for the breakthrough of high-density optical disk memory since wavelength limit of conventional lens-optics is not applied. We have proposed a MEMS for the near-field optical data storage, which consists of integrated optical micro-probes and a micro media-translation-table. Three-dimensional lithography based on the bulk micromachining using resist spray coater is applied to the integration of waveguide, micro-pinhole tip, cantilever, and photodiode for the MEMS probes. The media-translation-table consists of the inverted scratch drive actuators (inverted SDAs) fabricated by surface micromachining.

As the recording density of longitudinal magnetic storage increases at a 100% annual growth rate, it will soon approach the superparamagnetic limit where the thermal energy at room temperature starts to induce thermal instability to the grains in the small recorded marks. Thermal magnetic recording schemes, such as those used in magneto-optical recording, help alleviate the problems with the superparamagnetic limit. Recently, a hybrid recording system was proposed where data were recorded thermal magnetically on a magneto-optical disk and read back with a GMR head. In this paper, we propose an integrated planar read that combines an optical fiber lens, a solid immersion lens, a sub wavelength aperture, a micro coil, an air bearing surface, and a GMR head for such a hybrid recording system. Preliminary fabrication and calculation are discussed.

Molecular microsystems, which can operate as actuators, are of high current interest in a variety of diverse micromechanical applications. We present novel polymer-based microsystems, which undergo optomechanical cycles induced by ns laser pulses. It is demonstrated that these opto-actuators can be accurately controlled in a step-by-step manner by proper manipulation of the incident laser pulses. The photoinduced actuation relies on the reversible photochemical changes of photochromic spiropyran molecules incorporated into polymer matrices. In particular, the spiropyran molecule is converted reversibly between its isomeric forms, upon irradiation at appropriate laser wavelengths. These photochromic inter-conversions were found to activate the polymer matrix, resulting in its contraction and lengthening in a highly controllable manner. The reversible optomechancial actuation is demonstrated by laser-induced bending of microcantilevers made of photochromic polymers. The pathways of the optomechanical cycles are being well defined and correlated with stereoisomeric states of the photochromic dopants. The correlation is performed after fluorescence emission measurements of the photochromes in polymers matrices, upon appropriate pulsed laser irradiation.

In this paper a new approach for the design of tong grippers for micro-parts is presented. The grippers are made up of two independent jaw-actuator-sensor units that are coupled by an electronic control instead of a mechanical transmission. Electronic coupling of the jaws lowers the need for expensive precision mechanics and allows extracting information about the gripping situation. Each unit can very precisely position the gripping jaw and measure very small forces. The units act like small adjustable weighing machines. The gripping jaw is guided by a flexure hinge structure. The major characteristic is the frictionless and even movement of the gripping jaws. The jaw movement is driven by a moving coil actuator that takes advantage of the characteristics of the flexure hinge structure. The displacement of the gripping jaw is monitored by a magnetic displacement sensor. This approach allows building smart grippers that are able to analyze the gripping situation. Appropriate actions of the robot could be triggered based upon the gripper’s information. Thereby the efficiency of the assembly process could be improved. Prototypes using this approach have been realized. The properties of these prototypes have been tested in an experimental evaluation.

Shell-type micromechanical resonators operating in radio frequency range were fabricated utilizing mechanical stress that is built into polysilicon thin films. Significant increase of the resonant frequency (in comparison with flat, plate-type resonators of the same size) and the rich variety of vibrating modes demonstrate great potential for "2.5-Dimensional" MEMS structures. A finite curvature of the shell also provides a mechanism for driving resonators by coupling in plane stress with out of plane deflection. By modulating the intensity of a low power laser beam (P~10μWatts) focused on the resonator we introduced a time-variable, in-plane, thermomechanical stress. This stress modulation resulted in experimentally observed, large amplitude, out-of-plane, vibrations for a dome-type resonator. A double laser beam experimental setup was constructed where mechanical motion of a shell-type resonator was actuated by a modulated, sharply focused Ar⁺ ion (blue) laser beam and detected by a red HeNe laser using an interferometric setup. A positive feedback loop was implemented by amplifying the red laser signal (related to the oscillator deflection) and applying it to modulate the blue (driving) laser beam. Stable self-sustained vibrations were observed providing that the feedback gain was high enough. Employing a frequency selective amplifier in the feedback loop allowed excitation of different modes of vibrations. Fine frequency tuning was realized by adjusting the CW component of either lasers' intensity or a phase shift in the feedback loop. Frequency stability better than 1 ppm (10^-6) at 9 MHz was demonstrated for self-sustained vibrations for certain modes of the dome-shaped oscillators.

Electrothermal actuation is not a popular technology for today’s MEMS transducers due to its relatively slow response and large appetite for power. The large displacement with high force and low voltage gives reason to try to improve thermal actuator’s operating characteristics. This paper describes some improvements to thermal actuators, mainly in increased output energy per actuator chip area and area utilization. The devices presented here are a variation of the chevron thermal actuator - one with two sets of thermally expanding beams pushing at a slight angle on either side of a suspended shuttle, causing it to be displaced parallel to the substrate. One improvement is to taper the thermal expansion beams so they exhibit a higher strain energy, allowing a larger thermal input power and hence more output mechanical power per beam. Another improvement is to move (fold) both sets of thermal beams to the same side of the shuttle so all are exerting force on the same side. The thermal expansion beams cause compression against the shuttle and work against one or two orthogonal cold beams in tension to produce an output force and displacement. This resembles a pseudo-bimorph array with the exception of having far fewer non-force-producing beams to bend.

The classical laminated plate theory is modified in the present work to study the nonlinear electro-mechanical coupling in smart electrostrictive actuators. An iterative and a closed-form solutions are developed to estimate the mechanical and electrical response of electrostrictive laminates due to electrical and/or mechanical excitation. Both the numerical and the analytic schemes give almost identical solutions, which shows that a nonlinear coupling term in the constitutive relation of electrostrictive materials is insignificant.

An electronic circuitry is proposed and implemented to optimize the ignition process and the robustness of a microthruster. The principle is based on the integration of propellant material within a micromachined system. The operational concept is simply based on the combustion of an energetic propellant stored in a micromachined chamber. Each thruster contains three parts (heater, chamber, nozzle). Due to the one shot characteristic, microthrusters are fabricated in 2D array configuration. For the functioning of this kind of system, one critical point is the optimization of the ignition process as a function of the power schedule delivered by electronic devices. One particular attention has been paid on the design and implementation of an electronic chip to control and optimize the system ignition. Ignition process is triggered by electrical power delivered to a polysilicon resistance in contact with the propellant. The resistance is used to sense the temperature on the propellant which is in contact. Temperature of the microthruster node before the ignition is monitored via the electronic circuitry. A pre-heating process before ignition seems to be a good methodology to optimize the ignition process. Pre-heating temperature and pre-heating time are critical parameters to be adjusted. Simulation and experimental results will deeply contribute to improve the micropyrotechnic system. This paper will discuss all these point.

Several microsystem realizations are presented in this paper, which embed MEMs within a sigma-delta analog to digital (A/D) converter. A first category performs the readout and A/D conversion of capacitive sensors, while a second category, in addition to the readout and A/D conversion, provides advanced control techniques such as Proportional-Integral (PI) or Proportional-Integral-Derivative (PID) servo control to improve linearity and stability. A design methodology for this latter category is presented. For the readout-only microsystems category, the examples of pressure and acceleration readout are presented with SOI-based micromachined MEMs. Worst-case A/D conversion resolutions of 12 bits on 100Hz bandwidths are reported, with typical power consumptions for the A/D parts of around 500 μWatts. The pressure sensor microsystem includes full on-chip digital filtering and an RF powering and data transmission module for implanted applications. For the readout and servo control category, a porous silicon needle integrating a heating resistor and thermopiles is used to perform thermal conductivity measurements. Average A/D conversion resolution of 13 bits for 100Hz bandwidth is obtained and worst-case temperature regulation accuracy is 0.08 °C. Power consumption of the circuit remains around 500 μWatts. Detailed measurement results underline the valididy of the considered approaches for the implementation of high-compactness, high-resolution, improved-stability and low-power microsystems.

A simple valveless micropimp is fabricated using optical lithography and copper electroplating. The micropump is activated by magnetic force produced by two opposite spiral flat coils. Each coil consists of 30 tracks with 6mm diameter and 320m2 cross section. The micropump is fabricated between the two flat coils. By applying a square wave signal to the coils, they generate an alternative magnetic field, which contracts and expands the pumping chamber repeatedly causing the liquid in the pump to flow. Increasing the activating frequency, up to 300Hz, appears to increase the flow rate. Increasing the applied current, which is limited to the cross-section of the coil tracks, will increase the magnetic force and hence improve the pumping rate.

The increasing demands in MEMS fabrication in the past led to new requirements in production technology for these devices. Especially the packaging and assembly of optical devices like high power diode lasers require high accuracy in positioning and high reproducibility in combination with low production costs. Conventional assembly technology and mechanical adjustment methods are time consuming and exspensive. Therefore a need of new assembly procedures arose. Each component of the system has to be positioned and fixed. The equipment for manipulating is very expensive. Also adjustment of the parts after joining requires additional mechanical devices that need to be accessible after joining. The decreasing dimensions of the microsystems cause problems in assembly and increase dramatically the tolerance conditions The laser beam micro forming as a non-contact tool offers the possibility of active adjusment after the assembly is completed. This paper describes this new technology pointing out the used mechanisms of laser induces deformation: From the basic mechanisms dedicated structures are derived to achieve the desired degrees of freedom for the adjustment process. Based on the upsetting mechanism the positioning of a cylindrical lens in front of a high power diode laser is shown. The adjustment in two degrees of freedom can be realized by irradiating the actuating structure from one direction. The achieved accuracy is in the micron range. The knowledge transfer to a tube-like actuator will be demonstrated. The tilting of a mirror in two rotational movements will be shown. The results to be presented have partially been achieved within the Collaborative Research Center (SFB) 440 "Assembly of Hybrid Microsystems" which was financially supported by the Deutsche Forschungsgemeinschaft DFG.

Although lots of works have been devoted to develop the microactuators or microstructures, few researches have been done on three-dimensional microactuators. Here the feasibility investigation on a three-dimensional electro-thermally driven long-stretch micro drive (LSMD) is proposed by integrating the LSMD and mechanical hinge mechanism. The LSMD (about 2000 μm×500μm) consists of two cascaded compliant structures in parallel. Each cascaded structure is formed by connecting several basic actuation units in series. The mechanical hinge is used to allow the LSMD to be lifted as a three-dimensional structure. One of the important issues in fabricating the three-dimensional microactuator is the conducting circuit to actuate the microactuator. Here the Ni electroplating process is used to fabricate the mechanical hinge structure and the LSMD, then the mechanical hinge itself can act as the conductive circuit easily. From the LSMD simulation results, several design parameters are found to have significant influence on the output displacements. Larger out-stretching displacements are feasible by proper choice of design parameters. Preliminary fabrication results of nickel-made LSMD exhibit output displacement of 190 μm at input voltage of 3 volts. Fabrication results of nickel-made three-dimensional LSMD are also presented

Combinations of micromachined platforms and chemically sensitive micro-beads have been demonstrated for use as multi-analyte chemical and biological agent detectors. Two critical requirements for bead-based chemical detection platforms are bead retention and assembly. Separate “cover layers” have been used in the past for retention, but this constrains fluid flow through the device, and may require the use of precision spacers. In addition, since chemical sensing molecules within the beads can be quite sensitive exposure to high temperatures or harsh chemicals used in micromachining must be avoided after beads are placed in the platform. Here we present a new device whose fabrication is completed before placing the beads, and that provides both bead confinement and a means for self-assembly of arrays. Simple micromachined flexible “fingers” are used for all functions. The micromachined fingers are designed to bend out of the way as a bead is placed into a micromachined storage well, but then snap back after the bead is fully inserted into the well. We have also demonstrated that by designing different sized openings over each well it is possible to construct self-assembling bead arrays.

Micrometer sized cantilevers can be used as highly sensitive bio/chemical sensors and are usually fabricated in silicon. Here, we demonstrate the integration of an array of polymeric cantilever sensors into a microfluidic system designed for bio/chemical detection. The cantilever-sensors as well as the microfluidic system are fabricated in the polymer SU-8. Gold strain gauge resistors are incorporated in the cantilevers in order to make them sensitive to changes in surface stress. The cantilever device is fabricated as two separate parts, which are subsequently bonded together using SU-8 as glue. The sensitivity and noise response of the polymeric cantilevers are measured. The measured noise level indicates that the device is suitable for molecular recognition measurements.

To win the cancer is one of the most important mankind task to be decided in III Millenium. New technology of treatment is to recognize and kill cancer cells with the laser light not by surgery operation, but by soft painless therapy. Even though from the beginning of the 80s of the last century this technology, so-called photodynamic therapy (PDT) has received acceptance in America, Europe and Asia it is still considered in the medical circles to be a new method with the little-known approaches of cancer treatment. Recently the next step was done, and the unique method of PDT combined with laser-induced thermotherapy (LITT) was developed. Compact and smart diode laser apparatus “Modul-GF” for its realization was designed. In this report the concept of this method, experimental materials on clinical trials and ways of optimization of technical decisions and software of apparatus “Modul-GF”, including the autotuning of laser power dependently on tissue temperature measured with thermosensors are discussed. The special instruments such as fiber cables and special sensors are described to permit application of “Modul-GF” for the treatment of the tumors of the different localizations, both surface and deeply located with using of the endoscopy method. The examples of the oncological and nononcological pathologies’ treatment by the developed method and apparatus in urology, gynecology, gastroenterology, dermatology, cosmetology, bronchology, pulmonology are observed. The results of clinical approval the developed combination of PDT&LITT realized with “Modul-GF” leads to essentially increasing of the treatment effectiveness.

This paper presents an overview of fluidic technology - a technology that provides an additional dimension to conventional microfluidic technology by adding sensing, computation (both analog and digital) and control. The US Army Diamond Ordnance Fuze Labs officially recognized fluidics as a comprehensive technology comparable to electronics with its announcement in 1959. Because fluidic elements have very few or no moving parts the technology provides significant operational advantages in harsh environments (EMI, radiation, high temperature and vibration). It also offers advantages when dealing with fluid variables (flow, pressure, density, viscosity, etc.) by eliminating the need for interfaces. With the elimination of the inertia and friction associated with moving parts there are even greater advantages as a result of higher speed of operation. Where mechanical and micromechanical devices may be limited to only hundreds of hertz true microfluidic systems can operate at tens of thousands of hertz. We discuss the fundamental principles of jet deflection amplification and vortex modulation and present circuit building blocks such as the laminar proportional amplifier, vortex valve, oscillators, and positive-feedback digital components. However, most importantly, we present and discuss three specific applications illustrating the power of fluidics in microfluidics and MEMS. These are: a gas analyzer-on-a-chip, capable of simultaneous analysis of multiple gas mixtures with clinical accuracies; an intermittent oxygen delivery system that provides supplemental oxygen to ambulatory patients through a nasal cannula; and, an array of vortex microvalves capable of controlling propellants for micropropulsion systems or for the temporal and spatial modulation of fuel for the optimal control of gas turbine combustors. A sampling of other fluidic in microfluidic application are mentioned to include pressure and acoustic amplification (a kosher public address system is referenced), active noise cancellation for aircraft engines and passenger compartments, optical-pneumatic transduction in optical fiber missile controls and natural gas processing, angular rate sensing, and microcytometry for cellular processing. Fluidics may be the enabling technology for many as yet undeveloped applications, particularly when recent advances micro-fabrication are taken advantage of.

In this paper, we present the details of a optical fiber sensor, based on evanescent wave absorption in Long periodic grating (LPG) in multimode optical fibers, for measuring trace amounts of chromium concentration in water. The detection limit of the sensor is a few parts per billion (ppb) and the operating range is more than 3 orders of magnitude. The sensing length of the sensing element is only 10mm, but the dynamic range is as good as that of the conventional unclad evanescent wave sensors. A plastic clad silica core (PCS) fiber with LPGs on its middle region acts as the sensing element. Exposure of this sensing region to water samples containing spectroscopic reagents for the detection of chromium causes evanescent wave absorption, which increases with increasing concentration of chromium. The use of a super-bright green light emitting diode (LED) as light source reduces the size and cost of the system considerably. In order to reduce the effect of power supply fluctuations or ambient variations of the LED, a reference arm and ratio detector are employed.

The aim of this paper is to report the experimental setup designed, developed and tested in order to achieve the first vibrating mode of a lateral cantilever with mechanical excitation. The on-plane oscillating cantilever is the basis of a proposed mass sensor with an expected resolution in the atto-gram scale. In a first system design, the cantilever is driven electrostatically by an electrode, which is placed parallel to the cantilever. The cantilever is driven to its first resonant mode applying an AC voltage between the cantilever and a driver. Also, a DC voltage is applied to increase the system response. The signal read-out of the transducer is the capacitive current of the cantilever-driver system. The mass sensor proposed, based on this cantilever-driver structure (CDS), is integrated with a CMOS circuitry in order to minimize the parasitic capacitances, that in this case take special relevance because of the low level output current coming from the transducer. Moreover, the electrostatic excitation introduces a parasitic current that overlaps the current due to the resonance. The mechanical excitation is an alternative excitation method which aim is to eliminate the excitation current. Here we describe the experimental facilities developed to achieve mechanical excitation and report preliminary results obtained by this excitation technique. The results are complemented with dynamic simulations of an equivalent system model that are in accordance with the experimental values.

In this paper a novel capacitive micro-vibration sensor with multi-folding beams, fabricated by bulk micromachining, is presented. The microstructures of the vibration sensor are simulated by the finite element method (FEM). The relations between the structural parameters and the sensitivity and frequency response of the sensor were considered in the simulation. The static and modal analyzing results of the sensors show that the higher sensitivity and mechanical strength with multi-folding beam structure were achieved. The microstructure with beam thickness under 400um can be fabricated with DRIE technology. When the area of silicon proof mass is 2.5×10⁵ μm2, and the thickness of the proof mass vary from 40 μm to 80 μm, the mechanical noise is about 9×10^-6g/√Hz. The sensor with resonant frequency up to 5kHz can be used to measure the vibration signal in a wider frequency range.

A simple, easy-to-use and reliable method called nano-bending method is proposed to measure the residual stresses of surface-micromachined structures for MEMS (Micro-Electro-Mechanical Systems). The basic concept is based on the fact that the linear bending stiffness of the surface-micromachined bridge is affected by the residual stress of the consisting materials. It is preferentially necessary to know anchor stiffness and bending stiffness of the surface-micromachined cantilevers in the stress free state which are composed of the same materials as the surface-micromachined bridges. The usefulness of the method was demonstrated by poly-silicon surface-micromachined structures under various residual stresses. The results indicated that the measured residual stress of the as-deposited poly-silicon film is 142.70 MPa with standard deviation of 3.5 percent and the compressive residual stress decreases as growing the annealing effect.

We are going to present a new technology for laser bending of silicon microstructures based upon a suggestion of and carried out in cooperation with Prof. Dr. J. Frühauf from the Technical University Chemnitz (see acknowledgement). We investigated the influence of various laser process parameters on the bending angle and its reproducibility. Bending of the silicon element as a result of the laser induced thermal stresses in the material occurs toward the incident laser beam. The bending angle depends on a lot of laser process and material parameters. In particular we found that the irra-diation regime is well suited to control the bending angle. First substantial FEM based calculations of laser induced temperature fields using a moving laser heat source show the temperature field propagation in the material and reveal some regions of complicated overheating. As a result of our experiments we show a variety of examples including mul-tiple and also continuous bendings. There are several essential advantages compared to conventional bending technologies with this new method: Laser bending is contactless without using additional tools or external forces. Because of the local laser treatment the heat flux to the neighbouring material is minimized. The laser beam can be applied through windows of glass that means to al-most hermetically sealed micro devices. So laser technology is suitable for machining of already finished microsystems. It opens up a wide field of applications in micro system technologies: clip-chip-mechanism or sliding chips for micro optical benches, the adjustment of optical mirrors or other components or the ability of continuous bending for electro-static drives and so on.

Micromechanical devices and systems sometimes require a nanostructured addition or subtraction of material to obtain a more specific functionality. Silicon micro-technology is able to generate smart devices, but is facing a very complex processing to generate nano-structured areas to specialize the device, which are required only in small numbers. Here the very high resolution technique of three-dimensional electron beam nanolithography with chemically induced reactions can help. This technique is performed as a bottom up direct write or etch technique using a dedicated electron beam system with beam control and the possibility to add on chemicals using molecular beams, which can be switched on and off, and with a concentration matching the chemicals required to the lithography action. Etching oxides and carbides allows to structure very hard materials. Depositing oxides, metal or metal carbon compounds allows to add on specific three-dimensional nano-structures. Surfaces can potentially be modified to become specially chemically active or protected, and electronic circuitry can potentially be added in situ, which are built using vacuum micro-electronic devices to amplify or switch signals. This leads to novel nano-analytical devices and many applications. The technology is described. Applications are presented, e.g. in nano-optics with the rapid prototyping of photonic crystals, in nano-electronics with a micro-triode, and in nano biotechnology with surface structures. A comparison of electron-, ion- and laser-beam induced reactions is given.

Thin-film Pt nano interdigitated electrodes realized by combining e-beam lithography and standard photolithography are presented. The resulting nano-IDAs have an active area of 76 μm × 100 μm, an electrode pitch of 785 nm and a gap of 250 nm. The initial results show that this technology is well adapted for the realization of sub-micrometer metallic structures.

A method of characterization without contact of passive microstructures is presented in this paper. Samples of different SiO₂-Au microcantilevers (lengths from 100μm to 300μm, width 40μm, thickness 1.1μm) were studied by means of a Michelson interferometer. Two measurement techniques were employed, one by impulse response and the other by synchronous detection, in order to obtain the microcantilevers Eigen resonant spectrum and thus to determine their first three resonant frequencies. The knowledge of these frequencies makes possible the determination of the Young’s modulus of material and thus simplifies the modeling of the microsystem.

Electron beam lithography (EBL) is widely used for patterning of sub-micron and nano-scale patterns. Patterns in the order of tens of nano meters have been successfully realized using EBL. There are increasing needs in high aspect ratio structures in sub-micron and nano scales for microelectronics and other applications. Traditionally, high aspect ratio structures in sub-micron and nano scales have been realized by precision lithography techniques and subsequent dry etch techniques. In this work, we present commercially available SU-8 as a potential resist that can be used for direct resist patterning of high aspect ratio structures in sub-micron and nano scales. Such resist pattern can be used as a polymeric mold to create high aspect ratio metallic sub-micron and nano scales structures using electroplating technology. Compared to the most commonly used EBL resist, PMMA (poly methylmethacrylate), SU-8 requires a factor of 100~150 less exposure doses for equal thickness. It results in a significant reduction of EBL processing time. In this paper, characterization results on the patterning of up to 4:1 aspect ratio SU-8 structures with minimum feature size of 500 nm is reported. In addition, preliminary results on high aspect ratio metallic sub-micron structures using electroplating technology are also reported.

SU-8 photoresist has been popularly used as a mold for electroplating and facilitated low-cost MEMS production in many previous researches. However, the reachable thickness of electroplated structures standing on the substrate were limited to 50 μm below due to the internal stress and deformation of the SU-8 resist in final stripping process. In order to fabricate thicker structures, an embedded root method has been proposed to consolidate the adhesion of the metal structures to the substrate during the SU-8 removal process. In this paper, detailed investigation on this method is conducted to characterize the relationship among the root depth, the line-width and the allowable thickness of the electroplated structures. Some test patterns with embedded roots are designed and tested to generalize the possible extent of various structural scales associated with different niches in depth, which are completely defined through SiO₂ masking and KOH etching processes. Based on establishment of the relationship between the root depth and the geometric sizes, a 3-D integrated coil with 200 μm in thickness, 80 μm in width and 4 μm in root depth is successfully released by the SU-8 mold with 400 μm in height, which can not be achieved by the standard SU-8 molding process. The UV-LIGA process presented herein may be applied to the fabrication of other microstructures and microactuators.

As telecom networks increase in complexity there is a need for systems capable of manage numerous optical signals. Many of the channel-manipulation functions can be done more effectively in the optical domain. MEMS devices are especially well suited for this functions since they can offer large number of degrees of freedom in a limited space, thus providing high levels of optical integration. We have designed, fabricated and tested optical MEMS devices at the core of Optical Cross Connects, WDM spectrum equalizers and Optical Add-Drop multiplexors based on different fabrication technologies such as polySi surface micromachining, single crystal SOI and combination of both. We show specific examples of these devices, discussing design trade-offs, fabrication requirements and optical performance in each case.

We present a new MEMS mirror device that fulfills the requirements needed for its use in a wavelength selective switch. The MEMS device consists of a 1D array of individually controllable tilt micromirrors with almost 100% filling factor. Each mirror in the array is used to manipulate an individual wavelength channel, attenuating or redirecting it into a different output. The mirrors are electrostatically rotated around a fixed pivot and they use a novel concept of angle amplification to increase their out-of-plane angular rotation. A detailed analysis of their mechanical and optical response is presented.

In recent years, the image of the MEMS based fiber-optic industry has been plagued by a wave of product launch delays and cancellations. Long been of great interest to the academic community, MEMS based solutions have suffered from a focus on the MEMS alone and an underestimation of the complexity of productization. What is needed for successful development is the implementation of the system approach in MEMS product development. The essence of this approach lies in developing a thorough understading of all the requirements and constraints at the product level, not just the MEMS level. This will reveal all the intricate design interdependencies and trade-offs between all the different technologies involved, from MEMS to manufacturing, and provide confidence in the development timeline and marketability of the final product. A variable optical attenuator is presented that was designed from the ground up using the system approach which has resulted in the smallest size, lowest cost, market accepted solution.

We report our progress on the design and fabrication of electrostatically-actuated microelectromechanical (MEM) tunable wavelength filters and vertical cavity surface-emitting lasers (VCSELs). We investigate both an all-semiconductor monolithic approach and a hybrid approach based on the combination of conventional polysilicon microelectromechanical systems (MEMS) and III-V semiconductor thin-film distributed Bragg reflector (DBR) and VCSEL structures. In the tunable hybrid structures the III-V semiconductor layers are flip-bonded onto specially designed polysilicon foundry MEMS structures and separated from their lattice-matched parent substrates by a novel post-bonding lift-off process.

In this paper, a back-to-back micromirror device fabricated through surface-micromachining and flip chip packaging technologies is developed for optical add/drop multiplexer applications. Pre-stressed beams were designed to elevate micromirror devices after the release and thermal heat-treatment processes. Torsion flexure structure design provides a reliable rotation degree of freedom for micromirror devices. A mechanical stopper was bonded using flip chip packaging on the top of micromirror devices to constrain the popped-up micromirror to obtain precise deflecting angle. Preliminary experiments had demonstrated the feasibility of the micromirror devices.

Here the attenuation effect of a variable optical attenuator (VOA) with a tunable non-smooth mirror is investigated experimentally and analytically. The working principle of this VOA is based on the non-uniform deformation shape of a mirror membrane by thermally driven bimorph actuators. Before deformation, the surface roughness of Rymax and insertion loss of the mirror membrane are calibrated as 15 nm and 0.53 dB, respectively. The attenuation tests on smooth and non-smooth concave mirrors are also conducted. In simulation, the attenuation effects by various smooth spherical shapes are modeled by ray tracing method and Gaussian beam theory, and the simulation results are compared with experimental data. It is found that the attenuation behaviors between simulation and calibration results on smooth, spherical concave mirrors have good agreement. Also, by comparing the experimental results from smooth and non-smooth concave mirrors, the attenuation is found to be enhanced by the non-smooth mirror surface evidently. The maximum dynamic range of attenuation is found to be more than 40 dB at input voltage of 46 V.

Hexagonal micropillar (μ-pillar) cavities have been studied using 2-D finite-difference time-domain (FDTD) method. Singlemode resonances have been observed from a 2-μm sized hexagonal μ-pillar cavity that is selectively input-coupled. The simulated resonance wavelengths are consistent with the wavefront-matching condition based on ray-optics. The resonant field distribution has an integer number of field maxima along the cavity rim similar to whispering-gallery modes. Laterally waveguide-coupled hexagonal μ-pillar cavity channel add/drop filters with parallel and non-parallel waveguides have also been designed and simulated. Preliminary simulation of a 20-μm sized hexagonal μ-pillar cavity laterally coupled with 0.4-μm wide parallel waveguides demonstrated an extinction ratio of ≈ 8 dB, a signal/background ratio of ≈ 11 dB and a finesse of ≈ 5.

Silicon-on-insulator (SOI) technology offers tremendous potential for the integration of optoelectronic functions on a silicon substrate. In this research, we report on the fabrication process of a Mach-Zehnder interferometer on an SOI with 0.5μm wide waveguides in a Si layer of the order of ~1μm thick. These small dimensions increase the speed of these devices. However, with these small dimensions several fabrication difficulties such as alignment and thickness accuracy are present.

Because of their interesting electrical, mechanical and thermal properties at high frequencies, polymers are becoming more and more attractive in the development of RF and millimeterwave applications. Their process ease and characteristics indeed permit improvement in the performance of passive components as well as their integration especially with active devices. Investigated in this paper are a few technological solutions based on the use of thick polymer layers. The first one consists of a thick organic layer that may be employed as a dielectric membrane on bulk silicon micromachined substrates in order to realize suspended components, which exhibit thus very low losses and dispersion on a large frequency range. The elevation of passive circuits through thick polymers represents another attractive solution to minimize the losses induced by the silicon substrate, which through a low thermal budge provides a particularly attractive method for post-processing over active devices. The use of polymers for additional surface micromachining into coplanar slots on silicon substrates can also improve both losses and quality factor. Finally, an application using a thin polymer layer as dielectric protection for a MEMS device is described.

Numerical simulation of the affect of a micromachined tunable Fabry-Perot cavity on the performance of microbolometer is conducted. In particular, the ability of such a tuning structure to allow the determination of effective temperature of an object is studied. Assuming incoming infrared radiation from a blackbody source has a certain distribution of wavelengths for a specific temperature, and scanning over different Fabry-Perot gaps while using a total power detector such as a microbolometer, it is possible to predict the original blackbody spectrum. Comparing the original blackbody spectrum with the predicted spectrum, the optimum interval over which the gaps must be scanned can be determined.

Recent development of finline 35 GHz MEM modules like Gunn oscillator, PIN switch, and filters at Nanyang Technological University will be discussed. The design tools and measurement equipments like Advanced Design System (ADS), High Frequency Structure Simulator (HFSS) and Vector Network Analyzer (VNA) are used extensively throughout the work.

High frequency and high quality factor, Q, (defined as a half-width of the resonant peak) are the key factors that determine applications of microelectromechanical (MEMS) oscillators for supersensitive force detection or as elements for radio frequency signal processing. By shrinking the dimensions of MEMS resonators to the sub-micron range one increases the resonant frequency of the devices. Shrinking the devices, however, also increases the surface-to-volume ratio leading to a significant degradation of the quality factor (to below 5,000) due to the increased contribution of surface-related losses. We demonstrate that local annealing performed by focused low-power laser beams can improve the quality factor of MEMS resonators by more than an order of magnitude, which we attribute to the alteration of the surface state. Quality factors over 150,000 were achieved after laser annealing 3.1 MHz disc-type oscillators (radius R=10 micrometers, thickness h=0.25 micrometer) compared with a Q=6,000 for the as-fabricated device. The mushroom-type design of our resonator (a single-crystal silicon disc supported by a thin silicon dioxide pillar at the center) provides low heat loss and also confines the electron-hole gas created by laser excitation, enhancing light absorption. The combined power of a red HeNe laser (P_red=4mW) and a blue Ar+ ion laser (P_blue=5mW) focused on the periphery of the mushroom provides enough energy for surface modification. The post-treatment quality factor, exceeding 100,000 for MHz-range resonators, boosts the performance of MEMS to be comparable to that of lower frequency single-crystal quartz devices. The local nature of laser annealing, safe for surrounding electronics, is a crucial element for integration of MEMS resonators into an integrated circuit environment.

A multi-layer technology for electrical high-density connections between the two opposing sides of a wafer has been developed. Openings in a double-side polished wafer were created by applying a deep reactive ion etching technique. Hole structures with a diameter of 20 μm were formed through a 350-μm thick wafer. A multi-layer system of up to eight layers consisting of alternating conducting layers (N-type doped poly-silicon) and isolating layers (silicon-oxide) were grown until the vias were filled. Subsequently, all layers on the wafer surface were then removed in a CMP process. In this way, a multi-connection structure embedded in the silicon wafer can be fabricated. The applied low-pressure chemical vapor deposition techniques guarantee a sufficient homogenous coating outside and inside of the entire structure to a minimum layer thickness of one µm. The connection quality has been examined combining impedance spectroscopy and Focused Ion Beam technology. Depending on the geometry and the doping profile of the poly-silicon layers, a connection resistance of less than 80 Ohms can be achieved with sufficient DC isolation. In this way, a multi-connection of up to four isolated signal lines per opening was manufactured. This corresponds to a local connection density higher than 30.000/cm². The achievable connection density and the full CMOS compatibility of the applied processes make this multi-layer connection technology particularly well suited for combined MEMS and CMOS applications

Recently discovered extraordinary transmission of light through a thick metal plate perforated by regular hole array is in this paper studied for switching applications. Although this extraordinary transmission effect was first found in optical regime, it also occurs at microwave frequencies. In this study transmission of microwave radiation at normal incidence is theoretically studied through a semiconductor layer covered on both sides by a metal plate with regular hole array. At first, an analytical model for a metal plate perforated by dense regular hole array is presented. The metal hole array plate is modeled as a frequency dependent lumped inductance applicable for transmission-line modeling. Secondly, the properties of the semiconductor layer are considered. Silicon is a photoconducting material whose conductivity increases when exposed to optical illumination. With enough high optical illumination the perforated metal plate backed by semiconductor slab is like a metal conductor, and transmission through the structure is negligible. The whole structure, two perforated plates and the slab between them, is modeled using transmission-line techniques. The reflection and transmission coefficients are presented. Because the properties of the semiconductor slab can be controlled with optical illumination, we have optically controlled switch device for microwave transmission.

We report in this paper a new concept for 2.7 THz superconducting Niobium nitride (NbN) Hot-Electron Bolometer mixer (HEB). The membrane process was developped for space telecommnunication applications a few years ago and the HEB mixer concept is now considered as the best choice for low-noise submillimeter-wave frequency heterodyne receivers. The idea is then to join these two technologies. The novel fabrication scheme is to fabricate a NbN HEB mixer on a 1 μm thick stress-less Si₃N₄/SiO₂ membrane. This seems to present numerous improvements concerning : use at higher RF frequencies, power coupling efficiency, HEB mixer sensitivity, noise temperature, and space applications. This work is to be continued within the framework of an ESA TRP project, a 2.7 THz heterodyne camera with numerous applications including a SOFIA airborne receiver. This paper presents the whole fabrication process, the validation tests and preliminary results. Membrane-based HEB mixer theory is currently being investigated and further tests such as heterodyne and Fourier transform spectrometry measurement are planed shortly.

Observation and analysis of submillimeter-wave radiation (300GHz-3THz) in astronomy and atmospheric sciences requires increasingly performant receivers. The most sensitive receivers working in this range of electromagnetic spectrum use superconductor-insolator-superconductor (SIS) junctions. In order to increase the bandwidth and the sensitivity, we are developing a quantum-noise limited heterodyne receiver based on several parallel SIS junctions with broad (larger than 30%) fixed tuned bandwidth. These circuits can be viewed as passband filters which have been optimized by varying the spacings between junctions. We have designed such 5-junction arrays for operation in the range 480-640 GHz. Fabrication and heterodyne characterization of these devices has been done. The 1 μm² junctions current density ranges from 4 to 13 kA/cm², using optical lithography and Nb/Al2Nb5/Nb trilayer sputtering technology. The fabrication process and yield are presented in this paper, along with measured performances

In this work, a novel technology to fabricate small sized (~1cm²) c-Si photovoltaic minimodules is shown. This technology combines two main bulk micromachining techniques: fusion bonding and anisotropic etching of silicon. Due to the fact that the photovoltaic cells are fabricated in the same wafer, it is mandatory to etch the whole substrate to ensure electrical isolation. Once the individual cells are bulk-isolated they can be connected in series so as to scale up the output voltage of the miniarray. A handle wafer is required to provide mechanical stability to the device wafer. Fusion bonding is used to join the handle and the device wafer. First electrical results, under standard Air Mass 1.5 (AM 1.5) solar spectrum light (100mW/cm²), using a 9-cell serial connected minimodule, leads to a total open circuit voltage of 4.2V, a short circuit current of 2.5mA, and a maximum delivered power of 3.8mW each minimodule.

The effects of various deposition and annealing conditions of Plasma Enhanced Chemical Vapour Deposited (PECVD) oxide films on residual stress, optical index, BHF etch rate, surface roughness for thick PECVD oxide films are investigated. Rapid Thermal Annealing (RTA) and annealing in regular furnaces are both considered and compared. AFM measurements were required to measure the oxide surface roughness. Thick PECVD oxide films of 1.5 μm were deposited on 380 μm bulk silicon wafer. Starting from a conventional recipe the power, the [N₂O/SiH₄] ratio and the total gas flow were successively varied. An increase of the total gas flow or/and a decrease of power lead to an increase of the BHF etch rate and surface roughness but on the other hand decrease the residual stress. A high ratio N₂O/SiH₄ yields to oxide with low BHF etch rate but characterized by higher residual stress. RTA reduces the stress and the BHF etch rate drastically and it is more efficient than conventional annealing in standard furnace. Actually, RTA reduces stress in a very short period of time (few seconds) compared to standard annealing, and then it does not contribute to doping diffusion of the already implanted regions of the wafer. From a compressive stress of about 80 MPa, RTA of 15 s leads to a residual stress of only 30 MPa and bring the BHF etch rate to acceptable values in the range of 2000 Α/min for high N₂O/SiH₄ ratio oxide. One main application of this RTA stress release of oxide is to provide processed wafers with a bow compatible(less than 10 μm) with Chemical Mechanical Polishing (CMP) or wafer bonding.

Scanning Spreading Resistance Microscopy (SSRM) and Scanning Capacitance Microscopy (SCM) are two techniques based upon the atomic force microscope (AFM), which are used to obtain two-dimensional carrier maps of a semiconductor device’s cross-section. As all AFM techniques, they require probes with sharp tips to get good resolution images. Additionally, a hard and wear resistant tip material is needed to withstand the extreme mechanical stress tips are submitted to while a good conductivity is necessary for the characterization of highly doped areas of modern devices. In this work, several types of materials are evaluated based upon their mechanical and electrical characteristics: metals, hardmetals, conductive oxides and doped diamond. Commercial metal and diamond coated silicon tips are currently used (only diamond for SSRM). However, tips with thin metal coatings wear fast while the high resistivity of diamond limits the dynamic range. In both cases, the radius of curvature of coated tips is fairly large limiting the resolution. Probes with tips made out of TiN, a hardmetal, were manufactured using the molding technique. Using these tips, an ohmic point contact was obtained on Si. In SSRM mode, resistivity contrast was observed for the first time for a metallic tip. TiN tips also proved to be hard enough to penetrate the oxide and obtain SSRM images on InP. A good contrast and a monotonic behavior on n-type silicon in the absence of bias were obtained in SCM. The wear rate of TiN tips is lower than that of coated Si tips. However, despite their high hardness, TiN tips wore fast under high pressure and the tips died after a few SSRM scan lines on Si, and after a few images on InP.

MEMS device fabrication can benefit from accurate front- to backwafer alignment (FTBA) using Wafersteppers. To characterize FTBA an electrical overlay test structure is designed and fabricated to measure front- to backwafer overlay in a bulk micromachining process. Only two lithographic steps are required to fabricate these devices. The conductive film on the frontwafer, TiN, is virtually insensitive for mechanical damage during backwafer processing, and features a low etch rate in anisotropic KOH etching (2.4 nm/hr). Both FTBA overlay and FTBA CD variations are measured. The measurements shows that the front to backwafer overlay accuracy in bulk micro machining are limited by non-lithographic process errors.

The materials owning the rough surface have been adopted in many applications, such as MEMS devices, solar cell, DRAM, and so on. However, the modified targets on the previous methods were almost limited to silicon-type materials, and some had the limitations in the material properties. Recently, a process combining spin-on photoresist and one-step RIE was proposed to modify various materials, which can be etched by RIE. Here, a modification process, which combines spin-on photoresist, two-step RIE, and wet etching, is proposed to extend the feasible materials to be modified, because more materials can be etched by chemical solutions. Also, it is a low temperature process, and no extra mask is needed. From the experimental results, the modified surface can be used to alleviate stiction of microstructures, and a detachment length is found to be about 2.2 times longer than the cantilevers without the modified surface. Moreover, the related parameters for the anti-stiction are also developed, and the effects are compared with the previously developed one-step RIE method.

Color filter process is after passivation layer technology. Front end wafers may be produced by different size masks. For example, if front end stepper were 5" mask system, but color filter production line is 6 " mask, throughput will be very slow (6" mask but is 5" layout). Different foundries used different size masks & stepping systems (avoid guard ring) for production caused more complicated for different size masks matching. Color process use high energy, so may impact stepper throughput & Lens quality also. Improve throughput & prolong Lens life are very important for production. Using the matching system we can improve stepper (Example: 5"layout changed to 6" layout on 6" mask) throughput effectively & prolong ASML lens life.

This paper is about the definition and requirement of Compact lens system. One important application of the CMOS image sensor module is to capture a still image or continuous images when it is bundled with cellular phones (embedded, not add-on module). This type of application is related to the so-called “compact lens system.” We will make a description of image forming at pixel and image forming at chip and introduce the experiments of microlens shift. The discussion of the experimented results will include several factors: a) the color filter stack thickness b) the IC stack thickness c) fill factor d) the shape of photo diode. At last, check what problems may happen in actual microlens shift applications. From all above, we can understand the requirement of compact lens system.

Selective laser sintering (SLS) is a process that uses a rastering laser to sinter powder particles into a computer defined shape. In order to fabricate micro part with laser sintering the laser beam spot should be focused smaller, on the other hand the size of sintered powder particles should be smaller too. Therefore Nd:YAG laser doubling frequency is used to obtain mini-focus. Based on theories of nonlinear and resonant cavity, an equipment which perform frequency doubling on YAG laser(1.06μm) by the external resonant ring cavity has been designed. With the equipment the wave length of 0.532μm green light was output. The focused laser spot of 15μm diameter was obtained with 10W power. Meanwhile the micron metal powder was used in selective laser micro sintering (SLMS). The behavior of laser sintering different metal powder was investigated. Finally the micro Chinese characters which is small as a tip of match made with laser selective micro sintering micron metal powder are shown.

Micromechanical optical switches have good quality for free-space optical cross connects, particularly in terms of the low insertion loss, low crosstalk, polarization and wavelength-independence, and bit-rate transparency. In micromechanical optical switches, the electrostatic torsion beam actuator is widely used. But this actuator needs high-applied voltage. In this paper, using mechanical and electric characteristic, the relation between the translocation at the end of upper electrode and the applied voltage was derived. The applied voltage is in direct proportion to the cube of the torsion beam thickness, and reduces with the shorten of original distance between two adjacent electrodes. The actuator with the inclined under electrode was proposed and fabricated with certain tilting angle (111) silicon. Theoretical analysis indicates that the drive voltage based on the slant under electrode actuator can decrease half of that based on the flat under electrode.

There currently exists many optoelectronic methods of characterization of microstructures. We present here a dynamic method which uses the principle of the optical vibrometer in order to determine the oscillatory modes of microstructures. This measurement makes it possible to go up with the mechanical properties. It is a method without contact, based on the lighting of a microstructure using a laser beam guided by a lensed tapered optical fiber which will be used. Principal evolution of this technique is its miniaturization. It allows to integrate the device within a cryostat, where we will be able to carry out measurements with a control of temperature, pressure and composition of the atmosphere.

A bistable compliant micro-mechanism possesses the distinguish characteristics of both the bistable mechanism and the compliant one. It can be suitably employed in various MEMS devices, such as a micro-relay, an impact sensor, etc. Currently, preventing fracture and enhancing reliability are the most important issues in the application of bistable compliant micro-mechanisms. Through a systematic design methodology, including tuning the parameters of geometric shapes, adding a stopper at the proper position, etc., one can obtain a more appropriate micro-mechanism for designated applications. This paper proposes a systematic methodology for the design of bistable compliant micro-mechanisms.

A new type of resonator structure has been developed in thin film SOI applications. The resonator has circular shape and vertical vibration. By using conventional SOI chips with other electronics it is possible to add this resonator in same structure without complex process steps. The resonator is low mass resonator. It can be used in low frequencies (MHz) and high frequencies (GHz). The resonator has two electrostatically driven electrodes, one directly in resonator and another in substrate. Coupling rods are not needed. Also it is possible to build some kind of transistor on the resonator. By using this component, the transistor can be driven electrostatically. It can have higher voltage-current amplification- ratio rather than conventional transistor because of mechanical impact. Both structures will at least have Q-value of 700, which has been measured in 3,3MHz in normal room conditions.

A probabilistic approach has been used to analyze the stability of the various finite difference formulations for propagation of signals on a lossy transmission line. We extend the concept to consider the effects of space and time discretisations on the signs of the coefficients in a probabilistic finite difference implementation of the Telegraphers’ equation. We have found that if the sign of certain transition probabilities is negative then the algorithm is found to be unstable. The results of numerical analysis show that the following formulations of the diffusion and the Telegrapher’s equation gives the acceptable solutions: the backward difference, the central difference and Telegraphers’ equation with combination of central and backward differences. However the forward difference formulation of the diffusion equation gives the different results.

Micromechanical accelerometers are microscale sensors, whose operating principles and design theories are similar to those of conventional accelerometers. However, surface forces between mechanical structures become more important factors that affect the performance as microstructural size decreases. This paper discusses the effects of the electrostatic forces on the performance of open- and closed- loop micromechanical accelerometers, which are stiffness and damping change, and difference of the transfer function of the system.

Boron highly doped silicon is now widely used as etch stop layer in MicroElectroMechanical Systems (MEMS) devices fabrication. The present paper shows the advantages of replacing the p⁺⁺ Si etch stop layer by a p⁺⁺ polysilicon layer. The etch rate of Tetramethylammoniunhydroxide (TMAH) is measured for LPCVD polysilicon and silicon doped with Boron at concentrations from 8.10¹⁸ up to 4.10²⁰ atoms/cm³ which is the Boron solubility limit into Si. TMAH etch being often used during back-end process, selectivity to aluminium is usually needed. The etch selectivity of various TMAH solutions for p⁺⁺ Si, p⁺⁺ Poly and aluminium have been measured, from 25 % to 5 % TMAH pure and mixed with silicon powder and ammonium persulfate. Contrarily to silicon, polysilicon is etched isotropically in TMAH solution which constitutes a great advantage when cavities with vertical walls have to be opened. Although the polysilicon etch rate is higher than the silicon one, the selectivity (doped/undoped) is the same for the both materials, allowing identical uses. Another great advantage of polysilicon is that it can be deposited at any process step and does not require clever epitaxy steps or wafer bonding as for silicon. The surface roughness of the etched Poly region is considerably decreased with TMAH mixed with silicon powder and ammonium persulfate mixture compared to pure 25 % TMAH solution. The definition of buried masks in polysilicon layer through Boron implant is the main foreseen application. The p⁺⁺ Poly buried mask brings solutions for the fabrication of self-aligned double gate MOS, microfluidic or optical networks in MEMS field.

Ti_50.6Ni_19.4Pd₃₀ high-temperature shape memory alloy has been prepared exhibiting two kinds of phase transformation behavior. Tensile and thermal mechanical experiments were carried out to characterize the mechanical properties. It is found that the mechanical properties of the alloy showing B2-B19-B19’ two-stage phase transformation behavior changes compared with that showing B2-B19 one-stage phase transformation behavior. Complete linear superelasticity is obtained in both the two alloys. Owing to the high elastic modulus of B19’, a step exists in the modulus curves corresponding to B19-B19’ in the B2-B19-B19’ transformation; B2-B19 transformation is responsible for a trough in the modulus curves. A certain kind of training can significantly increase both the transformation strain and the superelastic strain, which are meaningful parameters in functional materials and smart structures.

High-precision laser radars and 3D vision systems with millimetre resolution require high-power picosecond optical pulses from laser diodes with direct current pumping in order to satisfy the requirements of low price, compactness and high reliability. A new laser diode capable of generating ~50 W / 20 ps optical pulses for such applications has been proposed recently, but one very important technical limitation for many industrial applications lies in its repetition rate, which is at present limited to ~ 50 kHz. This limitation originates from the heat dissipation in the Si-based, high-current nanosecond avalanche transistors used for laser pumping. It is shown in the paper, by using the 2D semiconductor device simulator, that the heat generation is powerfully localized in the avalanche transistor structure during the switching-on stage, but that in spite of this the associated thermal dynamics permits a higher maximum repetition rate than that observed experimentally. Moreover, smart designing of the semiconductor layers and construction of the heat sink should allow the limitation to exceed 1MHz. The lower limit observed so far in the experiments is caused by the stage of the voltage recovery across the transistor and may be softened by advanced circuit design.

A new circular position sensor based on giant magnetoresistances has been developed. The sensing film is an Ag_x-Co_1-x nanogranular thin film patterned in a circular Wheatstone bridge configuration over an alumina substrate. This alloy shows a high magnetoresistance of 8% at room temperature within the field generated by a neodymium-iron-boron permanent magnet. The sensor provides a sensitivity of 440 μV/V/(degrees) with an input voltage of 5V. The operation temperature range of this device is -40 degrees C~+120 degrees C although the magnetic film withstands higher temperatures up to 200 degrees C. The sensor assembly is able to attach an electronic interface in the rear of the alumina substrate to amplify and compensate the output signal. These parameters and the contact-less way of sensing make this device suitable for automotive applications. In addition, the sensor is insensitive to contamination, and devoid of friction and electrical contact noise therefore the sensor have a long lifetime.

The technique for investigation of thermoelectric, galvanomagnetic and thermomagnetic effects at ultrahigh pressure (up to 30 GPa) is presented. For micro-samples of chalcogens (Te,Se,S) and chalcogenides (n-PbTe,p-PbSe,p-PbS) the thermoelectric power, magnetoresistance and longitudinal and transverse Nernst-Ettingshausen effects have been measured. The systematical comparison of various effects in different materials are done. Effects obtained allowed to estimate the scattering parameter and mobility of charge carriers. It was shown the advantages of thermomagnetic technique over galvanomagnetic ones. Thus, from thermomagnetic effects the gapless state of materials was observed for the first time at room temperatures. The technique developed seems to be perspective for using in micro-device technology and thermosense industry. The work was supported by the Russian Foundation for Basic Research, Gr. No. 01-02-17203.

This paper mainly presents a briefly review for recent progress in MEMS-based transmission lines for use in microwave and millimeterwave range. MEMS-based transmission lines including different transmission line structure such as membrane-supported microstrip line microstrip line, coplanar microshield transmission line, LIGA micromachined planar transmission line, micromachined waveguides and coplanar waveguide are discussed. MEMS-based transmission lines are characterized by low propagation loss, wide operation frequency band, low dispersion and high quality factor, in addition, the fabrication is compatible with traditional processing of integrated circuits (IC’s). The emergence of MEMS-based transmission lines provided a solution for miniaturizing microwave system and monolithic microwave integrated circuits.

A 4-bit digital MEMS phase shifter, based on RF MEMS series switches and switched-line design, is presented. The phase shifter is fabricated on a 360 μm-thick silicon substrate, and the chip size is smaller than 5×8 mm ². The simulation performance of 16 phase states shows that at X-band the worst insertion phase deviation is 8 degree from the desired value, the insertion loss is less than -2.0dB and the VSWR is less than 1.8.

The oxidised porous silicon buried channel waveguides were fabricated by selectively anodized with a PMMA film mask and controlling the electric current density intensities and anodisation time during anodisation process is reported in this paper. The propagaion loss of this oxidised porous silicon buried channel waveguides was measured to be 9.2dB/cm.

Interpenetrating polymer network (IPN) hydrogel composed of sodium alginate (SA) and poly(diallyldimethylammonium chloride) (PDADMAC) exhibited electrical-sensitive behavior. The SA/PDADMAC IPN hydrogel was synthesized using the sequential IPN method. The swelling behavior of the IPN hydrogel was studied by immersion of the gel in aqueous HCl solutions at various concentrations and pHs. The stimuli response of the IPN hydrogel in electric fields was also investigated. When swollen IPN hydrogel was placed between a pair of electrodes, the IPN exhibited bending behavior upon the application of an electric field. The IPN also showed stepwise bending behavior depending on the electric stimulus.

A novel architecture for a lab-on-a-chip is presented. The architecture consists of a microfluidic system including integrated optical sensors and thin film transistors. The concept is based on the TFA (Thin Film on ASIC) technology that was developed at University of Siegen. The device consists of two substrate plates that are sandwiched together using oxygen plasma bonding. The thicker bottom plate contains the contacts to the microfluidic channels, while the thinner top plate contains the microfluidic system. The top plate is bonded face down onto the bottom substrate, and, on its reverse side, hydrogenated amorphous silicon (a-Si:H) based pin-diodes and thin film transistors (TFTs) are deposited for optical detection and data transfer. The pin-diodes and the TFTs are manufactured by PECVD (Plasma Enhanced Chemical Vapor Deposition) from silane, ammonia and dopant gases at temperatures around 200°C. Sputtered ZnO:Al is used as semitransparent front contact for the diodes, while Al and Cr are used as contacts to the transistors. The TFTs are used as switches to read out an array of pin-diodes. Experimental results for an electrokinetic microfluidic pump and the a-Si:H devices are reported. Further developments and potential applications for microanalysis are outlined.

The production of X-ray masks is one of the key techniques for X-ray lithography and the LIGA process. Different ways for the fabrication of X-ray masks has been established. Very sophisticated, difficult and expensive procedures are required to produce high precision and high quality X-ray masks. In order to minimize the cost of an X-ray mask, the mask blank must be inexpensive and readily available. The steps involved in the fabrication process must also be minimal. In the past, thin membranes made of titanium, silicon carbide, silicon nitride (2-5μm) or thick beryllium substrates (500μm) have been used as mask blanks. Thin titanium and silicon compounds have very high transparency for X-rays; therefore, these materials are predestined for use as mask membrane material. However, the handling and fabrication of thin membranes is very difficult, thus expensive. Beryllium is highly transparent to X-rays, but the processing and use of beryllium is risky due to potential toxicity. During the past few years graphite based X-ray masks have been in use at various research centers, but the sidewall quality of the generated resist patterns is in the range of 200-300 nm Ra. We used polished graphite to improve the sidewall roughness, but polished graphite causes other problems in the fabrication of X-ray masks. This paper describes the advantages associated with the use of polished graphite as mask blank as well as the fabrication process for this low cost X-ray mask. Alternative membrane materials will also be discussed.

In this paper, a concept for a monolithically integrated chemical lab on microchip is presented. It contains an ASIC (Application Specific Integrated Circuit), an interface to the polymer based microfluidic layer and a Pyrex glass cap. The top metal layer of the ASIC is etched off and replaced by a double layer metallization, more suitable to microfluidic and electrophoresis systems. The metallization consists of an approximately 50 nm gold layer and a 10 nm chromium layer, acting as adhesion promoter. A necessary prerequisite is a planarized ASIC topography. SU-8 is used to serve as microfluidic structure because of its excellent aspect ratio. This polymer layer contains reservoirs, channels, mixers and electrokinetic micro pumps. The typical channel cross section is 10μm•10μm. First experimental results on a microfluidic pump, consisting of pairs of interdigitated electrodes on the bottom of the channel and without any moving parts show a flow of up to 50μm per second for low AC-voltages in the range of 5 V for aqueous fluids. The microfluidic system is irreversibly sealed with a 150μm thick Pyrex glass plate bonded to the SU-8-layer, supported by oxygen plasma. Due to capillary forces and surfaces properties of the walls the system is self-priming. The technologies for the fabrication of the microfluidic system and the preparation of the interface between the lab layer and the ASIC are presented.

This paper describes the development of a technological process that allows the integration of gas sensors and thin film CMOS circuitry. The main technological points for the integration of gas sensors in a standard CMOS process and the effects on the full process will be described. A set of preliminary tests have been done prior to the definition of a CMOS compatible process for µ-structures and a complete test of sensitive materials are presented in order to determine the materials with most appropriate annealing temperatures for CMOS compatibility. Results show that gas sensors can be integrated with their circuitry, although require of special materials and non-CMOS standard processing as post-processing sequences.

Up to now, collimators have been generally produced by handwork and only a few companies have fabricated by semi-automatic system. Under this situation, automatic system for assembly of optical collimators has risen as the most essential technology in the development of optical communication components. In this study, it was projected to develop optical collimator with high-efficiency, and we manufactured it with a GRIN rod lens using automatic system. And then we carried out a performance test through a comparison of collimators made by automatic system and handwork system with angle alignment, beam size. Also we compared a common product with an auto-manufactured sample. As a result, it brought reduction of the tact time, improvement of efficiency and productivity of optical collimators. Therefore, it was found that automatic system was indispensable for commercialization of optical collimators with high-capacity.

Photoinduced absorption by VIS radiation in a-Si:H has been studied in-guide, in order to realise a novel all-optical waveguide micromodulator for application at 1.3 and 1.55 μm fiber communication wavelengths. In a-Si:H the photoinduced effects and the NIR absorption both involve dangling bonds states. The density of these states, deep in the gap, can be varied with doping. Therefore three waveguide prototypes have been fabricated by Plasma Enhanced Chemical Vapour Deposition on a silicon wafer. Their structure consist of a a-Si:H/SiO2 stack where the a-Si:H cores have different doping. The upper cladding is air. Optical measures on the core materials and signal transmission analysis in-guide at bit rates up to 200 kBit/s have been carried out. The excitation source of the VIS pump system for in-guide analysis consisted of simple, low cost AlInGaP LED’s controlled by a pulse generator. The pump and probe measures have been performed with different pump wavelengths and by varying the illumination intensity. LED’s with wavelengths of 644, 612, 590 and 571 nm have been alternatively used. For each pump wavelength, the light intensity was varied between 0,15 and 0,85 mW/mm². The results confirms that the optical modulation of the NIR signal enhances at high doping levels and for longer wavelengths. The modulation speed is probably limited by recombination phenomena.

The optical properties (the reflectance and the absorption) of the systems thin metal film - thick lithium niobate substrate (with film thicknesses of 15, 20, 30 and 40 nm) implanted by Ar⁺ ions with energies of 50, 100 and 150 keV and doses of 10¹⁵ - 10¹⁶ cm^-2 are investigated in the wide spectral range (λ = 0.2 - 15 μm). It is shown that ion implantation influence on the absorption and the reflectance of such systems. Intensive atoms intermixing on the interface “film - substrate” change the optical properties of such systems. Different materials result to different effects. The changes of surface structure of Ni and Mo film on lithium niobate substrate slowly influence on their optical properties. But Pd film on lithium niobate substrate result to independence of reflectance from wavelength in the wide spectral range with magnification of an adhesion of the film to the substrate. AFM investigations of such systems show changes of the surface structure of the samples after the implantation. The effective use of such materials for pyroelectric photodetectors is proposed. The characteristics of pyroelectric photodetectors on the base of the systems “thin metal (Ni, Mo, Pd) film - thick lithium niobate substrate” implanted by Ar⁺ ions were investigated and compared with similar photodetectors. Such photodetectors have high sensitivity, response, radiation stability, detectivity, large dynamic range. Their functional characteristics not worse that characteristics of similar photodetectors. Owing to high radiation stability (large adhesion of metal film to substrate) such metal film based pyroelectric photodetectors can effectively use for registration of power laser radiation. The production process of metal film based pyroelectric photodetectors implanted by Ar⁺ ions is also proposed.

In this paper we report about investigation of laser and laser-magnetron fabrication of nitride thin films (AlN, AlN:Mn, GaN, GaN:Zn, GaN:Cr) in quasi-closed chemically active ambience. On the base of conducted investigations it was found that the mode of deposition from both excited atoms and ions and chemically-active gas (nitrogen) can be realized depending on laser pulse energy, nitrogen pressure in the chamber and target-substrate distance what results in films formation with minimal deviation from stoichiometrical composition. Films crystallinity level and structure perfection depend on their growth rate on substrate surface. The complex of experimental and theoretical works on study of mechanical pressure in system AlN-Al₂O₃, is carried out by the analysis of elastic deformations. Is established, that the condensed layers as by laser and laser-magnetron methods were in is intense the deformed condition of compression. Basic regularities of pulse laser crystallization and cathodoluminescent brightness alteration dependencies on energy density of laser annealing were studied.

The work contains results of investigation on the phenomena of the field induced electron emission in thin oxide layers. As the emitters were used the thin doped films of In₂O₃ and SnO₂ (ITO-indium tin oxide) of thickness 10-300 nm deposited on 0.2 mm thick sodium glass plate. A negative voltage U_pol was applied to the sample’s field electrode. The ITO film was subjected to the bombardment by primary electron beam of energy E_p, which equals 200 eV. The field induced the secondary emission effect was studied in the 10^-7 hPa vacuum. The dependence of the secondary emission coefficient δ on the electric field was found to be not monotonic. The dependence δ= f(E_p) was also found to be different from that typically described in the literature. Energy examination of the emitted electrons revealed some electrons of energy higher than E_p. After removing the primary electron beam the electron emission still existed due to the applied electric field and it is called the electric field induced electron emission (EFIEE). The emission currents were of the order of nA. About 80% of the emitted electrons were found of energy within 1-2 eV, however few percent of the electrons exhibited energy approaching 10 eV. With increasing the applied voltage the emitted electron flux increased. It concerns mainly the low-energy electrons. The energy distribution of the electrons emitted under the EFIEE conditions from SI-SiO₂-ITO structures was also studied. The phenomenological model was proposed of the EFIEE effects. The main assumptions of the model are supported on the basis of the field induced division of the ITO semiconductor into two zones: depleted and enhanced of electrons.

A three-axis micro probe with wiring of the piezoresistors to Wheatstone bridges on the silicon membrane was currently developed for application in high precision coordinate measuring machines (CMM). The methods and results of the experimental investigation of the main properties of the 3d micro probe are presented. The influence of temperature and light onto the probe performance is described. Finally a brief outlook on the optimization of the threshold sensitivity is given.

One of main exploitation parameters of scanners, which determine their efficiency, is reflected beams deflection range. At present, this angle does not exceed ±3 to ±5 mrad, which does not satisfy modern requirements. Specific calculations for particular design versions do not reflect general rules of electrostatic microsensors’ snap-into-action. We have obtain the relations enabling to reveal general snap-into-action rules for torsion electromechanical devices due to introduction of relative values of the turn (bend) and the distance from the torsions’ axis to the beginning and to the end of immovable electrodes. Analysis of dependencies has shown that in equilibrium state condition it is possible, in principle, to obtain controllable anchor turning along the whole inter-electrodes gap. Design versions are proposed, which enable: to reduce electrostatic attraction forces due to reduction of immovable electrode length and giving a pointed shape to its end; to increase reactive moments in torsions under the anchor’s turn to a critical angle; to reduce electrostatic moment due to enlargement of inter-electrodes distance under the movable electrode ends to n times comparing to calculated values. The proposed directions of electrostatic fields and mechanical reactions change allow, under a permissible voltage increase in 1.5 to 2 times, to improve the main exploitation parameter of microscanners - mirror’s turning angle, which provides substantial broadening of their functional abilities.

New micro-machined VOA (Variable Optical Attenuator) is proposed, which has a micro shutter coated with light dissipative material such as Ti. A couple of tapered fibers are aligned with each other through optical path on the VOA chip. The optical path is composed of air path and the shutter of a microstructure. In the conventional study, reflective materials such as Au, Al, Cu and so on are used as a coated material for the micro mirror or micro shutter to improve the optical performance of VOA. The optical performances are composed of polarization dependent loss (PDL), wavelength dependent loss (WDL), return loss (RL) and so on. The optical characteristics of VOA usually depend on the shape of micro shutter, and on the coated material of micro shutter and on optical path. This paper proposes a new shape of shutter and a dissipative material like titanium to improve the optical performances. The new VOA in this paper is fabricated using silicon micro machining process. The structure of VOA is fabricated by ICP (Inductively Coupled Plasma) deep etch process, with SOI (silicon-on-insulator) wafer, which has 80μm thick layer and 3μm thick oxide layer. The new proposed VOA shows fast response time of the MEMS actuator and the excellent optical performances such as PDL and WDL. This paper shows that new designed shape and proposed material of micro shutter are useful to get excellent optical performances, compared with conventional model.

SiO₂/rotated Y-cut, X-propagating LiNbO3 leaky SAW substrates with a large k²(over 0.2) and zero TCF at a small thickness of SiO₂ of H/λ=0.2 (H: SiO₂ film thickness, λ: (SAW wave-length) compared to those of other substrates and zero propagation attenuation in the case of metalized surface. Theoretical and experimental results for low-loss filters, resonators and resonator filters are described. The low-loss filters using (FEUDT) showed an insertion loss of below 1dB at a center frequency of 400MHz and bandwidth of 20MHz using micro-fabrication technology. Also, the resonator showed wide-band characteristics and resonator filters showed a bandwidth of 89MHz at a center frequency of 500MHz.

Tungsten oxides thin films were obtained by electron beam deposition and annealed in the temperature range 350-800°C for 1-3 h. The structure, morphology and phase composition of the as-deposited and annealed films were characterized by X-ray diffraction and AFM. The electrical response towards NO₂ and O₃ was studied both experimentally and theoretically. In order to interprete the kinetic characteristics of tungsten oxide thin films upon exposure to different gases a model, based on surface adsorption/desorption processes coupled with bulk diffusion was used. A link between the geometrical and chemical heterogeneities of the tungsten oxide film surfaces and their performance characteristics as gas sensors was established. It was shown that the nature and the amount of the surface adsorption sites of the different non-stoichiometric phases (W_nO_3n-2 or W_nO_3n-1) or WO₃, and their conductive mechanism are defined from: the phase composition of the film, the crystallographic and electronic structure of the phases, the orientation of the crystallites within the film, and the geometrical form and dimensions of the crystallites. All tungsten oxide thin films investigated in this work are suitable to detect very low concentrations of NO₂ (0.05-0.5 ppm in N₂ and synthetic air) and ozone (25-90 ppb) at very low working temperatures (80-160°C). The films annealed at 400°C for 1-2 h are very selective to ozone and the films annealed at 400°C for 3 h and at 800°C for 1 h are very selective to NO₂.

It is common to underestimate the challenges of integrating the at least four technologies in any MEMS product: the three technologies of any semiconductor device (electronics, packaging and testing) plus the MEMS microstructure. For some specific areas of application, for example for photonics, optics technology/components must also be integrated. While traditional semiconductor devices utilize standardized and inexpensive packaging and testing procedures and equipment, MEMS require custom solutions that introduce multiple physical domains, such as light in the case of photonics, directly to a potentially moving structure on the die. This heightened complexity coupled with nonstandard packaging, testing and other (optics) technologies has a dramatic impact on functionality, reliability and cost. Being developed and successfully proven for a period of about twenty-five years the System Approach to MEMS Commercialization is based on three major principles: A priori understanding of the interdependence of technologies integrated into MEMS products: micro-machining, IC technology, packaging, testing and other (optics) technologies. Parallel development or implementation of these technologies within the MEMS product. Redistribution of manufacturing complexity from individual to batch realm. Integrating packaging and testing and other (optics) components into the microstructure and including some of the testing and functional algorithms in the ASIC reduce cost by simplifying more expensive individual manufacturing steps. The overall results of redistribution complexity from individual manufacturing technologies into batch manufacturing technologies are dramatic cost reduction, performance and quality improvement and shorter time to market.

Wafer-to-wafer bonding is the second, after wafer micromachining, most fundamental technology for MEMS. Independent on the specific application, bonding should provide certain level of bonding strength, which can be characterized by either pull or shear force required for delamination of the bonded wafers. It also should provide certain level of hermiticity or permability and some other characteristics such as level of induced stress during bonding, maximum temperature, thermo-mechanical stress due to the TCE difference, etc. The goal of presented novel class of bonding technologies is to decrease bonding area and increase mechanical strength and hermeticity of the bonding. This goal was achieved by a combination of the following: microprofiling the bonding area; making negative slope on the side walls of the trenches; making bridges; matching system of trenches and ridges; system of hooks; system of electrical outputs; spacers; barriers; system of capillaries for external true hermetization, etc. The common principle here is to use the third dimension - thickness of the wafer to achieve new quality, for example, to decrease bonding area on the surface of the wafer but increase total bonding surface and, therefore, increase mechanical strength and hermeticity.

Microfabrication techniques such as bulk micromachining and surface micromachining currently employed to conceive MEMS are largely derived from the standard IC and microelectronics technology. Even though many MEMS devices with integrated electronics have been achieved by using the traditional micromachining techniques, some limitations have nevertheless to be underlined: 1) these techniques are very expensive and need specific installations as well as a cleanroom environment, 2) the materials that can be used up to now are restricted to silicon and metals, 3) the manufacture of 3D parts having curved surfaces or an important number of layers is not possible. Moreover, for some biological applications, the materials used for sensors must be compatible with human body and the actuators need to have high strain and displacement which the current silicon based MEMS do not provide. It is thus natural for the researchers to look for alternative methods such as Microstereolithography (MSL) to make 3D sensors and actuators using polymeric based materials. For MSL techniques to be successful as their silicon counterparts, one has to come up with multifunctional polymers with electrical properties comparable to silicon. These multifunctional polymers should not only have a high sensing capability but also a high strain and actuation performance. A novel UV-curable polymer uniformly bonded with functionalised nanotubes was synthesized via a modified three-step in-situ polymerization. Purified multi-walled nanotubes, gained from the microwave chemical vapor deposition method, were functionalised by oxidation. The UV curable polymer was prepared from toluene diisocyantae (TDI), functionalised nanotubes, and 2-hydroxyethyl methacrylate (HEMA). The chemical bonds between -NCO groups of TDI and -OH, -COOH groups of functionalised nanotubes help for conceiving polymeric based MEMS devices. A cost effective fabrication techniques was presented using Micro Stereo Lithography and an example of a micropump was also described. The wireless concept of the device has many applications including implanted medical delivery systems, chemical and biological instruments, fluid delivery in engines, pump coolants and refrigerants for local cooling of electronic components.

Polymer based MEMS is rapidly gaining momentum due to their potential for conformability and other special characteristics not available with silicon microsystems. The polymer based nano- and micro-devices are flexible, chemically and biologically compatible, available in many varieties, and can be fabricated in truly 3-D shapes. The conceived devices thus are cheap and disposable. However, in order to conceive fully functional microsystems, necessary electronics have to be integrated. A modified organic thin film TFT is used for such integration. Although the existing technology of organic TFTs can not rival the well-established silicon semiconductor technology, especially in terms of speed, they are still useful in displays, disposable devices, and sensors. Although organic TFT and polymeric MEMS have several common features that make them compatible with each other, to the best of our knowledge, no serious attempt has been made thus far for combining these technologies. This paper is aimed at bridging this gap. Examples of potential micro sensors and systems, such as accelerometers and gyroscopes derived from polymer with functionalised carbon nanotubes are presented. A sensor-in-shoe demonstration will be performed at the Conference. Many issues and challenges in the design and development of polymer-based sensors with organic electronics are also addressed.

Infrared radiation imager is of important for a wide range of applications. IR infrared imagers have not been widely available due to cost and complexity issues. A major cost of IR imager is associated with the requirements of cooling and pixel-level integration with electronic amplifier and read-out circuitry that are often incompatible with the detector materials. Recent research activities have lead to a new class of IR imager based on thermally isolated MEMS (micro-electromechanical systems) arrays whose bending can be directly detected by optical means. This approach eliminates the need for cooling and complex electronic multiplexers, holding the potential to drastically reduce IR imager cost. However, MEMS based IR imaging devices demonstrated to date are less sensitive than the commercially available ones. We have established a comprehensive finite element model (FEM) using Ansys tool. An accurate computer model for the proposed MEME IR detector is critical for the device development and fabrication. The model greatly enhanced our capability to cost effectively optimize the design from concept to fabrication layout. Our model predicts the deformation of this pixel structure under a surface stress for both thermal and photo-induced effects under various conditions. This simulation model provided a design base for new generation of optical MEMS IR sensors that has higher sensitivity and the potential of incorporating passive thermal amplification. Our simple MEMS design incorporates optical read-out, which eliminates the drawback of electronic means that inevitably introduce additional signal loss due to thermal contact made to the detector element. When packaged under vacuum environment, significant sensitivity improvement is anticipated. The deflection of a cantilever as a function of a rise in its temperature is determined by the classical thermomechanical governing equation for a bimaterial cantilever beam. Our finite element model is established using brick element to mesh the structure for good accuracy. Numerical simulation procedures are as following:

A multi-layered surface acoustic wave (SAW) transducer employing an R.F. magnetron sputtered tungsten trioxide (WO₃) thin film as a selective layer, for low concentration nitrogen dioxide (NO₂) gas sensing is presented. The layered SAW device structure is fabricated on a 36° Y-cut, X-propagating LiTaO₃ substrate with a zinc oxide (ZnO) guiding layer. The dominant mode of acoustic propagation in the sensor is a combination of mainly a shear and a longitudinal displacement types. Such a structure has the advantage of confining the acoustic wave energy to the surface of the device, which increases the sensitivity of the system. A frequency shift of 30 kHz is shown for a concentration of 500ppb of NO₂ in synthetic air, highlighting the possibility of such a sensor being targeted towards the sub-ppb levels of NO₂.

This paper presents an optical fringe projection method for measuring the dynamic micro-components. Using a programmable liquid crystal display (LCD) projector and a long working distance microscope (LDM), sinusoidal fringes are projected onto a micro-component. The image of the fringe pattern is captured by another LDM and a high-speed camera and subsequently processed by the Fast Fourier Transform (FFT) technique. A simple procedure is described which enables calibration of the optical setup for subsequent amplitude and frequency measurement of the vibrating components. To overcome the underexposure problem, a white light source (WLS) is incorporated and the dynamic range of the camera is increased by a factor of 6. Discrepancy in the measured vibration amplitude is less than 1%.