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Recently lithium niobate on insulator (LNOI) has emerged as a promising platform for photonic integrated circuits (PICs) owing to the material’s high second order nonlinearity, a large transparency window and high piezo electric coefficients. Published results on LNOI range from efficient electro-optic modulators [1] to broadband supercontinua [2] – [4] . However, lithium niobate has a comparably high sensitivity towards optical damage processes such as photorefractive damage [5] , [6] . Their exact mechanisms are not yet fully understood and the impact on the long-term stability of LNOI devices has not yet been examined. Here, we present long-term measurements showing that during 400 hours of continuous irradiation with a mode-locked laser the supercontinuum spectrum remains stable.

We demonstrate that lithium niobate integrated photonics allows for reliable nonlinear applications under continuous femtosecond laser irradiation. Over >100 hours, a stable octave-spanning supercontinuum plus second-harmonic generation allows for direct self-referencing of a frequency comb.

The paper describes the fabrication of a silicon carbide piezoresistive pressure sensors intended for operating temperatures of up to 600°C. The different fabrication aspects, such as the metallization scheme, the etching of a 300μm deep cavity, and the bonding to a silicon carbide back plate are discussed in detail.

In future space missions for Universe and Earth Observation, scientific return could be optimized using MOEMS devices. Large micromirror arrays (MMA) are used for designing new generation of instruments. In Universe Observation, multi-object spectrographs (MOS) are powerful tools for space and ground-based telescopes for the study of the formation and evolution of galaxies. This technique requires a programmable slit mask for astronomical object selection; 2D micromirror arrays are perfectly suited for this task. In Earth Observation, removing dynamically the straylight at the entrance of spectrographs could be obtained by using a Smart Slit, composed of a 1D micro-mirror array as a gating device. We are currently engaged in a European development of micro-mirror arrays, called MIRA, exhibiting remarkable performances in terms of surface quality as well as ability to work at cryogenic temperatures. MMA with 100 × 200 μm2 single-crystal silicon micromirrors were successfully designed, fabricated and tested down to 162 K. In order to fill large focal planes (mosaicing of several chips), we are currently developing large micromirror arrays to be integrated with their electronics. 1D and 2D arrays are built on wafer with Through Wafer Vias in order to allow routing of the device on wafer backside, foreseeing integration with dedicated ASICs. The yield of these devices as well as contrast enhancement have been successfully implemented.

We have designed, fabricated and tested narrow-band Fabry-Perot filters in the infrared using gold porous mirrors and a silicon spacer layer. The filter peaks at 10 μm and 15 μm have approximately 10% transmission and a 1.5% linewidth. A Fabry-Perot structure with plane metal layers having a similar linewidth would have a transmission of only 0.2%. Thus, for the same linewidth we have improved the transmission by a factor of 50. Apart from the optical enhancements, these filters also have the advantage that they can be made inexpensively in a standard silicon MEMS technology and that their resonances can be finely tuned through post processing.

A method to improve the conduction and wear properties of nanometric conducting tips by forming silicides of Pt at the tip apex is presented. Tips with PtSi apexes are fabricated in conjunction with standard Si tips. Wear measurements are carried out on both tip types of similar geometries, and a one-on-one comparison between Si and PtSi at the nanoscale is shown for the first time. Both the wear properties on tetrahedral amorphous carbon and the conduction on Au of the PtSi tip apexes are shown to be superior to the Si tips. © 2006 IEEE.

Understanding friction1,2,3,4 and wear5,6,7,8,9,10,11 at the nanoscale is important for many applications that involve nanoscale components sliding on a surface, such as nanolithography, nanometrology and nanomanufacturing. Defects, cracks and other phenomena that influence material strength and wear at macroscopic scales are less important at the nanoscale, which is why nanowires can, for example, show higher strengths than bulk samples12. The contact area between the materials must also be described differently at the nanoscale13. Diamond-like carbon is routinely used as a surface coating in applications that require low friction and wear because it is resistant to wear at the macroscale14,15,16,17,18,19,20, but there has been considerable debate about the wear mechanisms of diamond-like carbon at the nanoscale because it is difficult to fabricate diamond-like carbon structures with nanoscale fidelity. Here, we demonstrate the batch fabrication of ultrasharp diamond-like carbon tips that contain significant amounts of silicon on silicon microcantilevers for use in atomic force microscopy. This material is known to possess low friction in humid conditions, and we find that, at the nanoscale, it is three orders of magnitude more wear-resistant than silicon under ambient conditions. A wear rate of one atom per micrometre of sliding on SiO2 is demonstrated. We find that the classical wear law of Archard21 does not hold at the nanoscale; instead, atom-by-atom attrition7,8 dominates the wear mechanisms at these length scales. We estimate that the effective energy barrier for the removal of a single atom is ∼1 eV, with an effective activation volume of ∼1 × 10−28 m3. Ultrasharp scanning probe microscope tips made of diamond-like carbon that contains silicon and oxygen demonstrate very high levels of wear resistance.

Structural variability and flexibility are crucial factors for biomolecular function. Here we have reduced the invasiness and enhanced the spatial resolution of atomic force microscopy (AFM) to visualize, for the first time, different structural conformations of the two polynucleotide strands in the DNA double helix, for single molecules under near-physiological conditions. This is achieved by identifying and tracking the anomalous resonance behavior of nanoscale AFM cantilevers in the immediate vicinity of the sample.

This paper presents a new fabrication technology for conducting AFM cantilevers with integrated AlN-based piezoelectric actuators. A major effort has been done for the process integration of a high quality AlN layer onto the Si cantilever together with a high wear resistance, PtSi-based conducting tip. Functional AFM devices have been successfully tested in tapping mode imaging experiments. Such type of cantilevers are of great interest for dynamic AFM applications especially for tapping or dithering mode AFMs as well as for using the piezoelectric structures as an integrated position sensor.

For patterning organic resists, optical and electron beam lithography are the most established methods; however, at resolutions below 30 nanometers, inherent problems result from unwanted exposure of the resist in nearby areas. We present a scanning probe lithography method based on the local desorption of a glassy organic resist by a heatable probe. We demonstrate patterning at a half pitch down to 15 nanometers without proximity corrections and with throughputs approaching those of Gaussian electron beam lithography at similar resolution. These patterns can be transferred to other substrates, and material can be removed in successive steps in order to fabricate complex three-dimensional structures.

We report on wafer-level transfer technologies to integrate PZT-based radio frequency (RF) microelectromechanical-systems switches on CMOS. Such heterogeneous integration can overcome the incompatibility of PZT material with back-end-of-the-line (BEOL) CMOS technology. The PZT stack and the transfer process have been optimized to avoid degradation of the PZT actuators during the transfer. In particular, we have optimized the seed layer for the growth of highly oriented PZT on a patterned TiO2-Pt layer, optimized the electrodes structure, and developed an Al2O3 capping layer to prevent degradation of PZT during the transfer process. A full wafer-level transfer process and a selective transfer technology allowing the distribution of RF switches from one source wafer to many receiving wafers has been demonstrated. The latest transfer process demonstrated exhibits great potential for cost optimization of wafer-level transfer of microdevices. In a separate experiment, we have demonstrated the BEOL CMOS compatibility of our integration technique. Switch characterization showed insertion loss of less than 0.5 dB and an isolation better than 30 dB for the 0.4- to 6-GHz frequency range with 15-V actuation voltage.

In this work we describe the design, fabrication, and testing of a mass-balanced planar x/y-scanner designed for parallel-probe data storage applications. The scanner is actuated by comb drives, whose finger shape is improved using finite-element analysis to increase the force output. A mass-balancing concept is used for in-plane shock resistance; in the out-of-plane direction passive shock resistance is achieved using 1:40 aspect-ratio springs that are fabricated by deep reactive ion etching through the full thickness of a [email protected] wafer. A prototype device is presented and its performance is reported.

A microelectromechanical system actuator based on thermophoretic, or Knudson, forces is proposed using analytical calculations. It can potentially execute scanning or spinning motions of a body that is not mechanically attached to the reference substrate. For a silicon device of 100-mum diameter, it is calculated that it can be levitated at a distance of about 0.5 mum from a substrate and that it can execute scanning motion and use quasi-springs by laterally acting thermal forces. In this way, an engine with spinning motion of a floating body having a diameter of 200 mum with up to 5 kHz can be achieved.

Ultrahigh storage densities can be achieved by using a thermomechanical scanning-probe-based data-storage approach to write, read back, and erase data in very thin polymer films. High data rates are achieved by parallel operation of large two-dimensional arrays of cantilevers that can be batch fabricated by silicon-surface micromachining techniques. The very high precision required to navigate the storage medium relative to the array of probes is achieved by microelectromechanical system (MEMS)- based x and y actuators. The ultrahigh storage densities offered by probe-storage devices pose a significant challenge in terms of both control design for nanoscale positioning and read-channel design for reliable signal detection. Moreover, the high parallelism necessitates new dataflow architectures to ensure high performance and reliability of the system. In this paper, we present a small-scale prototype system of a storage device that we built based on scanning-probe technology. Experimental results of multiple sectors, recorded using multiple levers at 840 Gb/in2 and read back without errors, demonstrate the functionality of the prototype system. This is the first time a scanning-probe recording technology has reached this level of technical maturity, demonstrating the joint operation of all building blocks of a storage device.

We have developed a generic cost-efficient CMOS-compatible heterogeneous device integration method at wafer-scale level. This method enables the distribution of devices from one to numerous wafers using selective transfer technology. We have applied this method for the distribution of atomic force microscopy (AFM) cantilevers and successfully demonstrated the population of multiple wafers from one source wafer. The distribution function has been designed such as to populate 42 wafers with only one source wafer. This CMOS back-end-of-the-line compatible method is particularly suitable for microelectromechanical systems and integrated circuits. Electrical interconnects are compatible with this technology. We present the concept, the selective transfer method, including a laser ablation technique used for the transfer, as well as the process and results of the application for AFM cantilever distribution.

We describe a planar microelectromechanical systems (MEMS)-based x/y nanopositioner designed for parallel-probe storage applications. The nanopositioner is actuated electromagnetically and has x/y motion capabilities of plusmn60 mum. The mechanical components are fabricated from a single-crystal silicon wafer using a deep-trench-etching process. To render the system robust against vibration, we utilize a mass-balancing concept that makes the system stiff against linear shock, but still compliant for actuation, and therefore results in low power consumption. We present details of the finite-element model used to design the device as well as experimental results for the frequency response, actuation, and vibration-rejection properties of the nanopositioner

The thermomechanical scanning-probe-based data storage concept, internally known as the ''millipede'' project, combines ultrahigh density, small form factor, and high data rates. Ultrahigh storage densities of more than 1 Tb/in^2 can be achieved by using local-probe techniques to write, read back, and erase data in very thin polymer films. In this paper special focus is given to the crucial role of the polymer storage medium in thermomechanical probe storage systems. High data rates are achieved by parallel operation of large 2D arrays with thousands micro/nanomechanical cantilevers/tips that can be batch-fabricated by silicon surface-micromachining techniques. The very high precision required to navigate the probe tips over the storage medium is achieved by MEMS-based x/y actuators that position the large arrays of probe tips for parallel write/read/erase operations. The inherent parallelism, the ultrahigh areal densities and the small form factor may open up new perspectives and opportunities for application in areas beyond those envisaged today.

We successfully fabricated single-crystal silicon cantilevers with spring constants as low as 10−5 N m−1 for use in magnetic resonance force microscopy applications. The fabricated ultra-thin silicon cantilevers had thicknesses ranging from 200 to 400 nm, lengths ranging from 340 to 450 µm and a width of 5 µm. We characterized their force sensitivity in the vacuum range from ambient pressure to 10−3 Pa and the temperature range from 15 to 300 K. A minimum value is observed for the internal friction, Q−1, at 160 K, which corresponds to an activation peak due to phonon scattering by atomic-scale defects. The best force sensitivity was achieved at 20 K, where it was increased by a factor of 10 as compared to that observed at room temperature.

We have developed a robust, CMOS back end of the line (BEOL) compatible, wafer-scale device transfer, and interconnect method for batch fabricating systems on chip that are especially suitable for MEMS or VLSI-MEMS applications. We have applied this method to transfer arrays of 4096 free-standing cantilevers with good cantilever flatness control and high-density vertical electrical interconnects to the receiver wafer (typically CMOS). Such an array is used in a highly parallel, scanning-probe-based data-storage system, which we internally call "millipede." A very high-integration density has been achieved, even for wafer-scale transfer, thanks to the interlocking nature of the interconnect structure, which provides easy alignment with an accuracy of 2 /spl mu/m. The typical integration density is 100 cantilevers/mm/sup 2/ and 300 electrical interconnects/mm/sup 2/. Note that only the cantilevers, not a chip with cantilevers, are transferred and, unlike flip-chip technology, our method preserves the device orientation, which is crucial for MEMS applications, where often the MEMS device should have access to its environment (in our case, the cantilever tips are in contact with the storage medium). After device transfer, the system is mechanically and electrically stable up to at least 500/spl deg/C, allowing post-transfer wafer processing.

Ultrahigh storage areal densities can be achieved by using thermomechanical local-probe techniques to write, read back, and erase data in the form of nanometer-scale indentations in thin polymer films. This paper presents single-probe experimental results in which large data sets were recorded at 641 Gbit/in/sup 2/ and read back with raw bit-error rates better than 10/sup -4/. (d,k) modulation coding is used to mitigate the effect of partial erasing, occurring when subsequent indentations are spaced too closely together, and to increase the effective areal density. The physical indentation profile, the sensitivity of the probe in readback mode, and noise sources that affect data detection are also discussed. Quantitative measurements of the partial erasing effect in both the on-track and cross-track directions are reported.

We describe a cantilever device for a novel time-of-flight scanning force microscopy (TOF-SFM) concept. The cantilever device consists of a switchable cantilever (SC), a microfabricated extraction electrode, and an Interlocking microstage. It allows quasi-simultaneous topographical and chemical imaging of a sample surface to be performed in the same way as with conventional scanning probe techniques. This is achieved by the micromachined SC with a bimorph actuator that provides a reasonable switching speed. Secondly, a short tip-electrode distance to minimize the ion extraction voltage can be realized by the help of the Interlock type assembling. The measured SC tip deflection is -100 µm at 35 mW, corresponding to an estimated heater temperature of ∼ 250 °C. The maximum switching speed between the two modes is ∼ 50 ms, and the sensitivity ΔR/R of an integrated piezoresistive deflection sensor is ∼ 6.7 × 10-7/nm. The tip-electrode distance is only 10 mm. The TOF-SFM system is currently being integrated in an ultra-high-vacuum system to perform first experiments.

We present the fabrication of thermomechanical cantilevers with nanometer-sized heaters used for data-storage application as implemented in the large two-dimensional cantilever array, known as the Millipede concept. Our goal is to explore how the power consumption of these cantilevers for the thermomechanical writing and reading process can be reduced by reducing the size of the heater structure. Such data are crucial for predicting the power consumption and data rate of storage devices using state-of-the-art CMOS manufacturing technology to achieve its associated minimum feature sizes. We describe the fabrication process and critical issues in connection with a complex device process that merges mix and match e-beam/optical lithography with the micro/nano electromechanical system (M/NEMS) fabrication technique. Fabricated cantilevers typically have a thickness of 100 nm, heater structures with lateral dimensions down to 180 nm, and critical feature alignment in the 50 nm range. We also present first experiments with such cantilevers, which highlight the scaling of the heater energy for the writing process provided by a nanometer-sized thermal constriction.

In thermomechanical data writing, a resistively-heated atomic force microscope (AFM) cantilever tip forms indentations in a thin polymer film. The same cantilever operates as a thermal proximity sensor to detect the presence of previously written data bits. This paper uses recent progress in thermal analysis of the writing and reading modes to develop new cantilever designs for increased speed, sensitivity, and reduced power consumption in both writing and reading operation. Measurements of cantilever electrical resistance during heating reveals physical limits of cantilever writing and reading, and verifies a finite-difference thermal and electrical simulation of cantilever operation. This work proposes two new cantilever designs that correspond to fabrication technology benchmarks. Simulations predict that the proposed cantilevers have a higher data rate and are more sensitive than the present cantilever. The various cantilever designs offer single-bit writing times of 0.2 /spl mu/s-25 /spl mu/s for driving voltages of 2-25 V. The thermal reading /spl Delta/R/R sensitivity is as high as 4/spl times/10/sup -4/ per vertical nm in near steady-state operation.

Present a new scanning-probe-based data-storage concept called the "millipede" that combines ultrahigh density, terabit capacity, small form factor, and high data rate. Ultrahigh storage density has been demonstrated by a new thermomechanical local-probe technique to store, read back, and erase data in very thin polymer films. With this new technique, nanometer-sized bit indentations and pitch sizes have been made by a single cantilever/tip into thin polymer layers, resulting in a data storage densities of up to 1 Tb/in/sup 2/. High data rates are achieved by parallel operation of large two-dimensional (2-D) atomic force microscope (AFM) arrays that have been batch-fabricated by silicon surface-micromachining techniques. The very large-scale integration (VLSI) of micro/nanomechanical devices (cantilevers/tips) on a single chip leads to the largest and densest 2-D array of 32/spl times/32 (1024) AFM cantilevers with integrated write/read/erase storage functionality ever built. Time-multiplexed electronics control the functional storage cycles for parallel operation of the millipede array chip. Initial areal densities of 100-200 Gb/in/sup 2/ have been achieved with the 32/spl times/32 array chip.

This paper reports an amorphous carbon (a-C) contact coating for ultra-low-ower curved nanoelectromechanical (NEM) switches. a-C addresses important problems in miniaturization and low-ower operation of mechanical relays: i) the surface energy is lower than that of metals, ii) active formation of highly localized a-C conducting filaments offers a way to form nanoscale contacts, and iii) high reliability is achieved through the excellent wear properties of a-C, demonstrated in this paper with more than 100 million hot switching cycles. Finally, a full inverter using a-C contacts is fabricated to demonstrate the viability of the concept. QC 20140521

Scanning probe microscopy (SPM) is a well-established technique for surface analysis, but batch-fabricated, low-cost probes still remain a challenging issue. The design and fabrication of entirely photoplastic probes for scanning force microscopy (SFM) have been developed and used for imaging DNA molecules. Using a polymer for the cantilever facilitates the realization of mechanical properties that are difficult to achieve with classical silicon technology. Single lever and cassettes of multiple single-lever probes are presented. The probes are made of an epoxy-based photoresist, which can be structured by standard photolithography and molding techniques. The fabrication process is a simple batch process in which the integrated tips and the levers are defined in one photolithography step. Imaging soft, condensed matter with photoplastic levers, which uses laser beam deflection sensing, exhibits a resolution that compares well with that of commercially available silicon cantilevers. A similar fabrication technique was also developed to fabricate photoplastic tips for scanning near-field optical microscopy (SNOM) that are to be attached to optical fibers. This technique allows optical apertures to be integrated at the end of the well-defined tip directly by probe fabrication, without the need for any post-processing for the aperture formation. Simple fabrication, as well as topographical and optical imaging with such probes, demonstrate the potential of photoplastic-based probes for AFM and SNOM applications.

We report on the 3D integration and interconnect of top-emitting VCSEL and photodiode (PD) arrays on a CMOS substrate. This technology represents a radically new way to increase the I/O bandwidth of processors and enables a path beyond 10Tb/s I/Os by using a high level of integration of opto-electrical devices (OED) directly on the processor. The integration process developed includes an OED placement of better than [email protected], OED thinning down to [email protected], and an interconnect technology with copper vias into the planarization polymer. Although the process is fully compatible with the back-end-of-line of CMOS, the experiments performed were done on dummy CMOS wafers. The opto-electrical characterization performed revealed a minimal impact of the integration process on the OED performance, demonstrating the high potential of the concept.

We report on a new atomic force microscope (AFM)-based data storage concept called the “Millipede” that has a potentially ultrahigh density, terabit capacity, small form factor, and high data rate. Its potential for ultrahigh storage density has been demonstrated by a new thermomechanical local-probe technique to store and read back data in very thin polymer films. With this new technique, 30–40-nm-sized bit indentations of similar pitch size have been made by a single cantilever/tip in a thin (50-nm) polymethylmethacrylate (PMMA) layer, resulting in a data storage density of 400–500 Gb/in. 2 High data rates are achieved by parallel operation of large two-dimensional (2D) AFM arrays that have been batch-fabricated by silicon surface-micromachining techniques. The very large scale integration (VLSI) of micro/nanomechanical devices (cantilevers/tips) on a single chip leads to the largest and densest 2D array of 32 × 32 (1024) AFM cantilevers with integrated write/read storage functionality ever built. Time-multiplexed electronics control the write/read storage cycles for parallel operation of the Millipede array chip. Initial areal densities of 100–200 Gb/in. 2 have been achieved with the 32 × 32 array chip, which has potential for further improvements. In addition to data storage in polymers or other media, and not excluding magnetics, we envision areas in nanoscale science and technology such as lithography, high-speed/large-scale imaging, molecular and atomic manipulation, and many others in which Millipede may open up new perspectives and opportunities.

We report the microfabrication of a 32×32 (1024) 2D cantilever array chip and its electrical testing. It has been designed for ultrahigh-density, high-speed data storage applications using thermomechanical writing and readout in thin polymer film storage media. The fabricated chip is the first very large scale integration (VLSI)-NEMS (NanoEMS) for nanotechnological applications. For electrical and thermal stability, the levers are made of silicon, and the heater/sensor element is defined as a lower, doped platform with the tip on top. Freestanding cantilevers are obtained with surface-micromachining techniques, which yield better mechanical stability and heatsinking of the chip than bulk-micromachining releasing techniques do. Two-wiring levels interconnect the cantilevers for a time-multiplexed row/column addressing scheme. By integrating a Schottky diode in series with each cantilever, a considerable reduction of crosstalk between cantilevers has been achieved.

The “Millipede” data storage concept is based on the parallel operation of a large number of micromechanical levers that function as AFM sensors. The technique holds promise to evolve into a novel ultrahigh-density, terabit-capacity, and high-data-rate storage technology. Thermomechanical writing and reading in very thin polymer (PMMA) films is used to store and sense 30–40 nm sized bits of similar pitch size, resulting in 400–500 Gbit/in 2 storage densities. High data rates are achieved by operating very large arrays (32 × 32) of AFM sensors in parallel. Batch-fabrication of 32 × 32 AFM cantilever array chips has been achieved, and array reading and writing have been demonstrated. An important consideration for the Millipede storage project is the polymer dynamics on the size scale of one bit. Scaling of rheological parameters measured for macroscopic polymer samples is likely to be incorrect due to the finite length of the underlying molecular polymer chain, a size that is comparable to the bit itself. In order to shed light on these issues we performed lifetime studies of regular arrays of nanometer size patterns using light-scattering techniques.

We present a 3D shadow mask technique for patterned modification of an area that is deeply recessed from the top surface with a large topographical step. The silicon shadow mask is micromachined such that it fits in a self-aligned fashion into the removed area of the device wafer and thus approaches the apertures close to the surface. Furthermore, owing to self-alignment between shadow and target, the lateral overlay precision is improved. The use of this technique is demonstrated for direct evaporation of metal patterns 10×50 μm 2 in size on the backside of a membrane of a bimorph-actuated device that is recessed by 500 μm. The same pattern dimensions were achieved in positive and negative resist by exposing it through the shadow mask aperture. We also show an application that uses a different type of shadow mask for the evaporation of an array of 25-μm wide metal wires across a step of 120 μm with no loss of dimension control. Full-wafer processing with the reusable shadow mask is demonstrated.

We report on an AFM-array concept (''Millipede'') for data storage of potentially ultrahigh density, terabit capacity, and high data rate. Thermomechanical writing and reading in very thin polymer films is used to store and sense 30-40-nm-sized bits with similar pitch size in very thin layers of PMMA, resulting in 400-500 Gbit/in^2 storage densities. Data rates of several hundred Mbit/s are envisioned by operating very large (32x32) 2D AFM arrays in parallel. We have successfully batch-fabricated first all-silicon 5x5 and 32x32 AFM cantilever array chips. They constitute a major step of the Millipede concept towards terabit storage systems with small form factor and high data rates. Our 32x32 array chip is the first VLSI-NEMS (Nano ElectroMechanical Systems) for nanotechnological applications.

New types of piezoresistive cantilevers for torque magnetometry have been microfabricated and tested. The design is optimized to detect the flexion and torsion of the cantilever corresponding to a torque in two directions, which is induced by a microscopic magnetic sample mounted on the lever surrounded by an external magnetic field. The high sensitivity (up to ≈10 −14 N m) of the device is achieved by its special geometrical design featuring cantilever legs with only 3-μm-wide beams. The microfabrication process makes use of silicon-on-insulator wafers for precise etch-stop of a novel deep-trench etch process from the backside to fabricate the individual chips. One cantilever version has an integrated metal loop for absolute calibration of the sensor within 1%. The loop can also be used to actuate the lever mechanically. Owing to their small dimension and mass, the new devices feature ultrahigh sensitivity combined with short response time, which allows the characterization of microscopic magnetic samples with very high resolution.

We describe a new O-ring setup for wet-etching processes of microelectromechanical systems (MEMS) . Our new low-cost approach using siloxane-based seal rings entails the single-side etching of silicon and silicon dioxide using potassium hydroxide and buffered hydrofluoric acid, respectively. With this approach, the wafer is not immersed into the etching solution, but only the side to be etched is in contact with the solution, hence the previously fabricated device elements on the other side of the wafer are not damaged. In one process for etching silicon the etch solution is heated by an infrared lamp. We describe the fabrication of various cantilever-based sensors, such as arrays of 0.8-um thick levers for a chemical/electronic nose, and 5-um-thick silicon cantilevers having piezoresistive sensors. Our technique has gooduniformity and process control and, in addition, eliminates mechanical stress on the fragile wafers incurred by wafer chucks, which are required for the conventional immersion approach. It has improved process yield and reduces the waste of chemicals.

An innovative method for fabrication and rapid prototyping of high-aspect ratio micromechanical components in photoresist is discussed. The photoresist is an epoxy-negative-tone resist, called SU-8, which can be structured to more than 2 mm in thickness by UV exposure. Small gears of 530 mu m in diameter and 200 mu m in thickness have been realized in this photoplastic and their functionality has been demonstrated. In addition a process called MIMOTEC(TM) (MIcroMOlds TEChnology) has been established for the fabrication of metallic micromolds. MIMOTEC(TM) is based on the use of the SU-8 spun on high thicknesses and electrodeposition of nickel. Thermoplastic microcomponents have been injected and mounted in watches.

We have built and operated a novel setup for the characterization and identification of gases or vapors based on sequential position readout via a beam-deflection technique from a microfabricated array of eight cantilever-type sensors. Each of the cantilevers can be coated on one side with a dif- ferent sensor material to detect specific chemical interactions. We demonstrate that disturbances from vibrations and turbu- lent gas flow can be effectively removed in array sensors by taking difference signals with reference cantilevers. For ex- ample, H2 can be detected by its adsorption on a Pt-coated sensor because a change in surface stress causes a static bending of the sensor. The diffusion of various alcohols into polymethylmethacrylate induces resonance frequency shifts in a dynamic measuring mode and bending in the static mode, which allows one to distinguish between the various alcohols. Sensor devices for detection of gases and vapors via spe- cific coatings are gradually gaining importance in chemistry, materials science, and biochemistry owing to the increas- ing demand for detection of analytes at monolayer coverage. A field of increasing interest is the construction of so-called "electronic noses" capable of discerning different odors via a typical response pattern of the receptor layers to an analyte. Most devices currently applied involve square centimeter- sized detection areas and comparatively large gas volumes (typically 50- 1000 cm 3 ) resulting in relatively long response

Detailed investigations of the limits of a new negative-tone near-UV resist (IBM SU-8) have been performed. SU-8 is an epoxy-based resist designed specifically for ultrathick, high-aspect-ratio MEMS-type applications. We have demonstrated that with single-layer coatings, thicknesses of more than 500 μm can be achieved reproducibly. Thicker resist layers can be made by applying multiple coatings, and we have achieved exposures in 1200 μm thick, double-coated SU-8 resist layers. We have found that the aspect ratio for near-UV (400 nm) exposed and developed structures can be greater than 18 and remains constant in the thickness range between 80 and 1200 μm. Vertical sidewall profiles result in good dimensional control over the entire resist thickness. To our knowledge, this is the highest aspect ratio reported for near-UV exposures and the given range of resist thicknesses. These results will open up new possibilities for low-cost LIGA-type processes for MEMS applications. The application potential of SU-8 is demonstrated by several examples of devices and structures fabricated by electroplating and photoplastic techniques. The latter is especially interesting as SU-8 has attractive mechanical properties.

Selective Ga + ion implantation and miring by focused ion beam exposure and subsequent wet chemical etching is used to fabricate micro/nanomechanical elements in Si. Freestanding elements with a ~ 30 nm membrane thickness are made by controlled selective underetching between unexposed and exposed areas. Ultrahigh-frequency cantilever beams have been made with resonances in the tens of MHz range. Using a U-shaped beam cross section, mechanical stiffness could be increased 100-fold, which in turn increased the beam resonance frequency to several hundreds of MHz. The direct-write patterning/milling technique was used to fabricate various arbitrary shapes with vertical sidewalls such as submicrometer-sized containers, cups, and other nanomechanical devices.

Heated tips offer the possibility to create arbitrary high-resolution nanostructures by local decomposition and evaporation of resist materials. Turnaround times of minutes are achieved with this patterning method due to the high-speed direct-write process and an in-situ imaging capability. Dense features with 10 nm half-pitch can be written into thin films of organic resists such as self-amplified depolymerization (SAD) polymers or molecular glasses. The patterning speed of tSPL has been increased far beyond usual scanning probe lithography (SPL) technologies and approaches the speed of Gaussian shaped electron beam lithography (EBL) for

THz-imaging enables promising applications in the medical and security domain, such as detectors for skin cancer or full-body scanners. These new possibilities arise the need for detectors in the THz frequency range. An antenna-coupled bolometer approach in a standard CMOS-SOI process, followed by a MEMS post CMOS process, is suggested to fabricate such a detector. Therefore, in this paper a cloverleaf shaped antenna design for the frequency range 0.5 THz to 1.5 THz is presented. Several design steps are shown together with measurement results regarding the influence of the MEMS process.

Thermal scanning probe lithography is used for creating lithographic patterns with 27.5 nm half-pitch line density in a 50 nm thick high carbon content organic resist on a Si substrate. The as-written patterns in the poly phthaladehyde thermal resist layer have a depth of 8 nm, and they are transformed into high-aspect ratio binary patterns in the high carbon content resist using a SiO2 hard-mask layer with a thickness of merely 4 nm and a sequence of selective reactive ion etching steps. Using this process, a line-edge roughness after transfer of 2.7 nm (3σ) has been achieved. The patterns have also been transferred into 50 nm deep structures in the Si substrate with excellent conformal accuracy. The demonstrated process capabilities in terms of feature density and line-edge roughness are in accordance with today’s requirements for maskless lithography, for example for the fabrication of extreme ultraviolet (EUV) masks.

A reduced-order model for NEM relays is presented that combines electro-mechanical beam actuation and landing of beam tip on the surface electrode. This model shows a deviation of less than 2%, for the DC as well as the transient response for beam actuation in a circuit simulation, when compared to a finite-element simulation. It also shows an excellent match for the energy. The model allows accurate circuit simulation to aid in NEM-relay based logic design, and facilitates the quantification of key gate-level metrics.

A new type of traveling wave antenna is presented. Key features of the antenna are planar, low mass and wide bandwidth of operation. One such antenna was designed for terahertz radiation detection and realized in standard IBM CMOS-SOI process with subsequent MEMS post processing. Measurements performed at 655GHz showed very good agreement with the theoretical predictions based on full wave simulations. The present article describes the antenna physics, design, fabrication and measurement results.