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High quality gratings are among the key elements for successful imaging with X-ray grating interferometry. Grating fabrication, specifically of absorption gratings, with high aspect ratio and large area, is a great challenge from a microfabrication point of view. In this paper the fabrication of absorption gratings by seedless electroplating of gold in high aspect ratio silicon moulds that are fabricated by deep reactive ion etching (Bosch process) is presented. We report on our latest results and discuss the possibility of reducing the grating period down to 1.3 μ m . In addition, the quality of the gratings is assessed by performing visibility measurements and imaging various samples on a compact in house X-ray grating interferometer.

We present a method to produce small pitch gratings for X-ray interferometric imaging applications, allowing the phase sensitivity to be increased and/or the length of the laboratory setup to be minimized. The method is based on fabrication of high aspect ratio silicon microstructures using deep reactive ion etching (Bosch technique) of dense grating arrays and followed by conformal electroplating of Au. We demonstrated that low resistivity Si substrates (, Micromachines, 12 (5), ISSN:2072-666X

The research field of metasurfaces has attracted considerable attention in recent years due to its high potential to achieve flat, ultrathin optical devices of high performance. Metasurfaces, consisting of artificial patterns of subwavelength dimensions, often require fabrication techniques with high aspect ratios (HARs). Bosch and Cryogenic methods are the best etching candidates of industrial relevance towards the fabrication of these nanostructures. In this paper, we present the fabrication of Silicon (Si) metalenses by the UV-Nanoimprint Lithography method and cryogenic Deep Reactive Ion Etching (DRIE) process and compare the results with the same structures manufactured by Bosch DRIE both in terms of technological achievements and lens efficiencies. The Cryo- and Bosch-etched lenses attain efficiencies of around 39% at wavelength λ = 1.50 µm and λ = 1.45 µm against a theoretical level of around 61% (for Si pillars on a Si substrate), respectively, and process modifications are suggested towards raising the efficiencies further. Our results indicate that some sidewall surface roughness of the Bosch DRIE is acceptable in metalense fabrication, as even significant sidewall surface roughness in a non-optimized Bosch process yields reasonable efficiency levels.

We report the design and implementation of a unique, wafer sized stretchable and bendable monolithic silicon matrix structure. The achieved stretchability allows for simultaneous omnidirectional folding, required to conform the structure to complex curved 3D surfaces. Moreover, it also enables dynamic mechanical deformation of the structure to cope with a moving environment, like e.g., the wall of the heart muscle. Due to the nature of the fabrication process, normal silicon wafer processing can be performed prior to rendering it stretchable. This is first demonstrated by the fabrication of two metal layers on top of silicon, which act as the electrical interconnects of a final flexible and stretchable LED-matrix. Currently, the possibility to postprocess an existing commercial CMOS process is investigated. This would lead to a revolutionary potential of new applications, especially in the medical field, by enabling complex silicon monitoring systems to be linked to organs without hindering them.

© 2018 IOP Publishing Ltd Printed in the UK. We report the design and implementation of a unique, wafer sized stretchable and bendable monolithic silicon matrix structure. The achieved stretchability not only allows for one directional folding, but is capable of bending in two directions simultaneously, which is required to conform the structure to complex shapes such as spheres, tori, hyperboloids or a combination of them. Moreover, it also enables dynamic mechanical deformation of the structure to cope with a moving environment, e.g. the wall of the heart muscle. The minimal measured bending radius is 8mm, which is 20% smaller than the current state of art. Furthermore, a new fabrication process is proposed that enables the use of common (1 0 0) wafers. This enables a broader and more accessible applicability compared to earlier work, which is based on non-standard (1 1 1) wafers, or the more expensive SOI wafers. The technique can lead to a revolutionary potential of applications, especially in the medical feld, by enabling complex silicon monitoring systems to be linked to organs without hindering them. ispartof: JOURNAL OF MICROMECHANICS AND MICROENGINEERING vol:28 issue:11 status: published

A three-dimensional topography simulation of deep reactive ion etching (DRIE) is developed based on the narrow band level set method for surface evolution and Monte Carlo method for flux distribution. The advanced level set method is implemented to simulate the time-related movements of etched surface. In the meanwhile, accelerated by ray tracing algorithm, the Monte Carlo method incorporates all dominant physical and chemical mechanisms such as ion-enhanced etching, ballistic transport, ion scattering, and sidewall passivation. The modified models of charged particles and neutral particles are epitomized to determine the contributions of etching rate. The effects such as scalloping effect and lag effect are investigated in simulations and experiments. Besides, the quantitative analyses are conducted to measure the simulation error. Finally, this simulator will be served as an accurate prediction tool for some MEMS fabrications.

In this paper, fabrication and testing of a miniaturized microcantilever-based particulate matter detector with integrated electrostatic on-chip ultrafine particle (UFP) separation and collection are presented. Mass added to the sensor causes a resonance frequency shift. To attract naturally charged particles, the cantilever is equipped with a collection electrode. In addition, a µ-channel is integrated, to improve the particle collection efficiency and to enable a size/mass-related particle separation. For electrical read-out, piezo-resistive struts are attached to the cantilever sidewalls near its clamping. This design offers high miniaturization potential, since no integration of transducing electronics on the cantilever beam is needed. The sensors are fabricated using Si bulk material and standard micromachining technology; the cantilevers have a thickness of 3 ± 0.5 µm, a width of 3.1 ± 0.3 µm, 5.9 ± 0.4 µm or 10.5 ± 0.4 µm and a length of 118.7 ± 0.8 µm, 168.8 ± 0.8 µm or 171.2 ± 1 µm, respectively. To this end, a front-side release process using cryogenic inductive-coupled plasma reactive ion etching was developed, which does not require additional sidewall passivation steps. Testing of the resonator function by operating the sensor inside a scanning electron microscope and reference measurements inside a temperature-controlled test chamber using synthetic carbon UFPs (~160 nm average mass concentration distribution) and a fast mobility particle sizer as a reference instrument were carried out. Here, the ability to detect low UFP mass concentrations in the range

The Fraunhofer IMS has recently developed a technique for producing nanoelectrodes that are generated by atomic layer deposition (ALD) in a via deep reactive ion etching (DRIE) structured sacrificial layer. This method enables the fabrication of CMOS- and biocompatible nanoelectrodes with suitable ALD-materials. Improvements of the established fabrication processes and the electrochemical characterization of such electrodes are presented. In the frame of the Fraunhofer-Max-Planckcooperation project ZellMOS different types of nanoelectrodes are studied. Their diameter is in the range of 200 nm and thereby sufficiently small to be taken up by living cells. In addition, the electrodes are mechanically enforced by an oxide layer at the nanoelectrodes’ bottom.

In this paper, we investigate the absorption of mid-infrared light by low resistivity silicon textured via deep reactive ion etching. An analytical description of the wave propagation in black silicon texture is presented, showing agreement with the experiment and the computational analysis. We also study the dependence of absorption spectrum of black silicon structure on the electrical conductivity of silicon substrate. The structures investigated unveil wideband, all-silicon infrared absorbers applicable for infrared imaging and spectroscopy with simple CMOS compatible fabrication suitable for optoelectronic integration.

The fabrication of a novel class of microgrippers is demonstrated by means of bulk microelectromechanical systems (MEMS) technology using silicon on insulator wafer substrates and deep reactive ion etching. Hard masking is implemented to maximize the selectivity of the bulk etching using sputtered aluminum and aluminum–titanium thin films. The micro-roughness problem related to the use of metal mask is addressed by testing different mask combinations and etching parameters. The O2 flow, SF6 pressure, wafer temperature, and bias power are examined, and the effect of each parameter on micro-masking is assessed. Sidewall damage associated with the use of a metal mask is eliminated by interposing a dielectric layer between silicon substrate and metal mask. Dedicated comb-drive anchors are implemented to etch safely both silicon sides down to the buried oxide, and to preserve the wafer integrity until the final wet release of the completed structures. A first set of complete devices is realized and tested under electrical actuation. [2017-0039]

A wide variety of MEMS micro-mirrors are being developed for various optical applications. One such application is Fourier transform spectroscopy (FTS). The design, process optimization, and fabrication of a micro-mirror for this application are presented. Large, nontilting displacements of mirrors are required to achieve high FTS resolution. Although, certain applications require lower resolution, the mirror still needs to be nontilting. In order to obtain this without using deep reactive ion etching (DRIE), the micro-mirrors were fabricated on silicon using bulk micromachining with wet chemical etching. This paper presents the process developed for fabrication of the mirror with the required specifications. In addition, results of the FTS experiments conducted with the micro-mirror will also be presented. � 2006 IEEE.

A novel micromachined X-ray collector using anisotropically etched Si(1 1 1) side walls as X-ray mirrors for future astronomical missions is reported. The collector was designed to converge a ϕ 100 mm parallel X-ray beam into a ϕ 4 mm focus. In order to obtain smooth Si(1 1 1) side walls, dynashock-type ultrasonic waves were added during the anisotropic KOH etching. The surface roughness on the order of nm or less was achieved. The sidewalls or the X-ray mirrors were diced from the wafer as mirror chips and then adhered to a mount formed by deep reactive ion etching. The first light image was successfully obtained at Al K α 1.49 keV in a ISAS 30 m-long X-ray beam line.

We demonstrate high aspect ratio silicon nanorod arrays by cyclic deep reactive ion etching (DRIE) process as a scaffold to enhance the energy density of a Si-based supercapacitor. By unique atomic layer deposition (ALD) technology, a conformal nanolayer of TiN was deposited on the silicon nanorod arrays as the active material. The TiN coated silicon nanorods as a supercapacitor electrode lead to a 6 times improvement in capacitance compared to flat TiN film electrode. Keywords: Supercapacitor, Silicon nanorod array, TiN nano film, DRIE, ALD

This paper covers the main technological and design aspects relevant to the development of a new generation of thin 3D pixel sensors with small pixel size aimed at the High-Luminosity LHC upgrades., 2 pages, 3 figures, 2015 Pisa Meeting

This paper presents a high-performance three-axis capacitive microelectromechanical system (MEMS) accelerometer implemented by fabricating individual lateral and vertical differential accelerometers in the same die. The fabrication process is based on the formation of a glass-silicon-glass multi-stack. First, a 35- $\mu \text{m}$ thick $\langle 111\rangle $ silicon structural layer of an Silicon-On-Insulator (SOI) wafer is patterned with deep reactive ion etching (DRIE) and attached on a base glass substrate with anodic bonding, whose handle layer is later removed. Next, the second glass wafer is placed on the top of the structure not only for allowing to implement a top electrode for the vertical accelerometer, but also for acting as an inherent cap for the entire structure. The fabricated three-axis MEMS capacitive accelerometer die measures $12\,\times \,7\,\times \,1$ mm3. The $x$ -axis and $y$ -axis accelerometers demonstrate measured noise floors and bias instabilities equal to or better than 5.5 $\mu \text{g}/\surd $ Hz and 2.2 $\mu \text{g}$ , respectively, while the $z$ -axis accelerometer demonstrates $12.6~\mu \text{g}/\surd $ Hz noise floor and $17.4~\mu \text{g}$ bias instability values using hybrid-connected fourth-order sigma–delta CMOS application specific integrated circuit (ASIC) chips. These low noise performances are achieved with a measurement range of over ±10 g for the $x$ -axis and $y$ -axis accelerometers and +12/−7.5 g for the $z$ -axis accelerometer, suggesting their potential use in navigation grade applications. [2014-0351]

A micromachined Faraday cup array (MFCA) has been developed using a deep reactive ion etching (DRIE) process for applications in position sensitive charged particle detection. Deeply etched trenches with vertical sidewalls create an effective ion collection structure, and the formation of MOS capacitors on the interior surfaces produces an array of low-leakage, high stability Faraday cups that can be independently addressed. Closely spaced, linear arrays of 64, 128 and 256 cups with pitches of 150 and 250 u?m have been fabricated and characterized. The narrow 50 u?m silicon web between each pair of Faraday cups provides electrostatic isolation with linear fill factors of 67 and 80%, respectively. These Faraday cup arrays enable a new generation of compact mass spectrometers which feature true multi-channel ion detection capability over a wide mass range. Since the entire array is always open to the incident ion flux, no ions are lost as in scanning mass spectrometer systems, and the overall sensitivity is drastically improved by a factor that is approximately equal to the number of cups in the array. The MFCA is thus an ideal component for miniaturized mass spectrometers, ion beam profiling, and chemical analyzers which must handle very small samples.

A new method of fabricating high aspect ratio nanostructures in silicon without the use of sub-micron lithographic technique is reported. The proposed method comprises two important steps including the use of CMOS spacer technique to form silicon nitride nanostructure masking followed by deep reactive ion etching (DRIE) of the silicon substrate to form the final silicon nanostructures. Silicon dioxide is used as the sacrificial layer to form the silicon nitride nanostructures. With DRIE a high etch selectivity of 50:1 between silicon and silicon nitride was achieved. The use of the spacer technique is particularly advantageous where self-aligned nanostructures with potentially unlimited lengths are formed without the need of submicron lithographic tools and resist materials. With this method, uniform arrays of 100 nm silicon nanostructures which are at least 4 μm tall with aspect ratio higher than 40 were successfully fabricated.

3D detectors with electrodes penetrating through the entire silicon substrate have many advantages over conventional planar silicon technology, for example, high radiation tolerance. High aspect ratio through-wafer holes are essential in such fabrication, and deep reactive ion etching (DRIE) is used. A series of DRIE processes were tested and optimised to achieve the required aspect ratio, and in 5-μm wide trenches, aspect ratios of 58:1 were achieved © 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

International audience; Diamond exhibits several attractive properties for bio-sensing applications. In particular its high bio inertness, high electrochemical stability, and optical transparency provide diamond with high interests for neural activity study. The purpose of this study is the realisation of microelectrodes arrays (MEA) in diamond for neurons slices study. Due to a cellular lysis on the edge of the tissue slices studied, electrodes have to be at least 60 μm in height even though the electrode surface has to be minimised in order to achieve good signal noise rate. Silicon MEA with metal contacts were realised using (Deep Reactive Ion Etching) DRIE and coated with Nanocrystaline Diamond (NCD) using (Bias Enhanced Nucleation) BEN technique. We focus the study on the understanding of the BEN nucleation process on such high aspect ratio electrodes. Several parameters such as slope of the substrate, conductivity and chemical nature of the substrate were studied in order to enable selective nucleation necessary to fabricate diamond MEAs. The study leads to the optimised development of a processing route enabling the selective coating of the active tips of high aspect ratio MEAs without altering the electrical insulation between probes.

We combine the particle swarm optimization (PSO) method and the continuous cellular automaton (CCA) in order to simulate deep reactive ion etching (DRIE), also known as the Bosch process. By considering a generic growth/etch process, the proposed PSO-CCA method provides a general, integrated procedure to optimize the parameter values of any given theoretical model conceived to describe the corresponding experiments, which are simulated by the CCA method. To stress the flexibility of the PSO-CCA method, two different theoretical models of the DRIE process are used, namely, the ballistic transport and reaction (BTR) model, and the reactant concentration (RC) model. DRIE experiments are designed and conducted to compare the simulation results with the experiments on different machines and process conditions. Previously reported experimental data are also considered to further test the flexibility of the proposed method. The agreement between the simulations and experiments strongly indicates that the PSO-CCA method can be used to adjust the theoretical parameters by using a limited amount of experimental data. The proposed method has the potential to be applied on the modeling and optimization of other growth/etch processes., We acknowledge the financial support from the National Natural Science Foundation of China No. 51375093, and the Ramón y Cajal Fellowship Program by the Spanish Ministry of Science and Innovation.

The second generation circular digital variable optical attenuator (CDVOA) with an effective area of 1500 μm diameter has been designed and fabricated based on SOI technology. C-band incoming Gaussian light can be reflected to an outgoing fiber from a shiny circular area, which is divided into sectors that can be individually tilted and addressed electrostatically to achieve variable light attenuation. Using a delay mask process, each movable component i) has an underlying ridge frame to maintain flatness, ii) is suspended by two micro beams at a bridge structure that connects to a handle where aluminum electrode is located underneath, and iii) is separated by wall structures at the handle area to reduce crosstalk from adjacent electrodes. Critical fabrication processes including the mirror and chip release are performed using a HF vapor phase etcher. Fluidic pressure and chip-dicing shocks are avoided. Initial results show that a mirror sector suspended by two 345 μm long beams with a cross-section of about 5×5 μm2 can be tilted to 2.8° at about 18 V driving voltage. Initial interferometric measurement gives estimated individual mirror flatness after metallic reflective coating to be about λ/15. The assembled chips are ready for further testing and characterization.

In recent years, optical stimulation in neuroscience has emerged as an alternative to electrical stimulation. In this work, we present the concept and optical simulation of an optrode capable of delivering focused infrared light to brain tissue, while simultaneously recording electrical signals from the surrounding area. The system combines the advantages of silicon microfabrication and silicon's transparency in the near-infrared. For efficient coupling into the probe and controlling the illuminated volume in the brain, silicon microlenses were simulated using MATLAB. The lens system can focus light in 2-D, with configurable focal length and spot size.

The shape and dimensions of an atomic force microscope tip are crucial factors to obtain high resolution images at the nanoscale. When measuring samples with narrow trenches, inclined sidewalls near 90 degrees or nanoscaled structures, standard silicon atomic force microscopy (AFM) tips do not provide satisfactory results. We have combined deep reactive ion etching (DRIE) and focused ion beam (FIB) lithography techniques in order to produce probes with sharp rocket-shaped silicon AFM tips for high resolution imaging. The cantilevers were shaped and the bulk micromachining was performed using the same DRIE equipment. To improve the tip aspect ratio we used FIB nanolithography technique. The tips were tested on narrow silicon trenches and over biological samples showing a better resolution when compared with standard AFM tips, which enables nanocharacterization and nanometrology of high-aspect-ratio structures and nanoscaled biological elements to be completed, and provides an alternative to commercial high aspect ratio AFM tips.