Add to Wishlist. USD Sign in to Purchase Instantly. Explore Now. Buy As Gift. Overview Master's Thesis from the year in the subject Engineering - Mechanical Engineering, grade: 1. The forerunner of this technology was mostly the electronics industry with their need of manufacturing processes for electronic components, like printed circuit boards and integrated circuits. The market of microsystem technologies is in general a very fast growing market.
However, the focus of the development is distributed different in certain countries. While the US has for example a focus on parts for micro-electro-mechanical systems MEMS , equipment for information technology, biomedicine and genetic engineering, Germany dominates in sensor technology for the automotive industry. Japan has traditionally a strong position in fine mechanics and precision engineering as well as in equipment for information technology and consumer goods. Until recently, the production of miniature components was focused on technologies, traditionally used in the electronics and semiconductor industry, like etching and other photofabrication techniques.
Using these technologies extremely small feature sizes can be produced. Optical lithography for example produces features as small as 0. Table 1. An introduction to these techniques is given in some papers which brie y summarize different micromachining methods. A very good paper was published by Masuzawa. The most complete description of different processes is included in the book 'Fundamentals of microfabrication: the science of miniaturization' by Marc J. Chris Mack. Application of artificial neural networks to compact mask models in optical lithography simulation. Compact mask models provide an alternative to speed up rigorous mask diffraction computation based on electromagnetic field modeling.
The high time expense of the rigorous mask models in the simulation process challenges the exploration of innovative modeling techniques to compromise accuracy and speed in the computation of the diffracted field and vectorial imaging in optical lithographic systems. The artificial neural network ANN approach is presented as an alternative to retrieve the spectrum of the mask layout in an accurate yet efficient way.
The validity of the ANN for different illuminations, feature sizes, pitches, and shapes is investigated. The evaluation of the performance of this approach is performed by a process windows analysis, comparison of the spectra, best focus, and critical dimension through pitch. The application of various layouts demonstrates that the ANN can also be trained with different patterns to reproduce various effects such as shift of the line position, different linewidths, and line ends. Comparisons of the ANN approach with other compact models such as boundary layer model, pulses modification, spectrum correction, and pupil filtering techniques are presented.
Inverse e-beam lithography on photomask for computational lithography. Computational lithography, e. The ideal design of a curvilinear mask for computational lithography requires many changes during photomask fabrication. These range from preparation of the mask data to measurement and inspection. The manufacturability of a photomask for computational lithography is linked to predictable and manageable quality of patterning.
Impact of nm photomask uncertainties on computational lithography solutions. Computational lithography solutions rely upon accurate process models to faithfully represent the imaging system output for a defined set of process and design inputs. These models rely upon the accurate representation of multiple parameters associated with the scanner and the photomask. Many input variables for simulation are based upon designed or recipe-requested values or independent measurements.
It is known, however, that certain measurement methodologies, while precise, can have significant inaccuracies.
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Additionally, there are known errors associated with the representation of certain system parameters. With shrinking total critical dimension CD control budgets, appropriate accounting for all sources of error becomes more important, and the cumulative consequence of input errors to the computational lithography model can become significant.
In this work, we examine via simulation the impact of errors in the representation of photomask properties including CD bias, corner rounding, refractive index, thickness, and sidewall angle. The factors that are most critical to be accurately represented in the model are cataloged. CD bias values are based on state-of-the-art mask manufacturing data, and other variable changes are speculated, highlighting the need for improved metrology and communication between mask and optical proxmity correction model experts.
The simulations are done by ignoring the wafer photoresist model and show the sensitivity of predictions to various model inputs associated with the mask. Impact of realistic source shape and flexibility on source mask optimization. Source mask optimization SMO is widely used to make state-of-the-art semiconductor devices in high-volume manufacturing.
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To realize mature SMO solutions in production, the Intelligent Illuminator, which is an illumination system on a Nikon scanner, is useful because it can provide generation of freeform sources with high fidelity to the target. Proteus SMO, which employs co-optimization method and an insertion of validation with mask three-dimensional effect and resist properties for an accurate prediction of wafer printing, can take into account the properties of Intelligent Illuminator. We investigate an impact of the source properties on the SMO to pattern of a static random access memory.
Quality of a source made on the scanner compared to the SMO target is evaluated with in-situ measurement and aerial image simulation using its measurement data. Furthermore, we discuss an evaluation of a universality of the source to use it in multiple scanners with a validation and with estimated value of scanner errors. Holistic optimization architecture enabling subnm projection lithography.
Parallel with the introduction of EUV lithography, immersion lithography is being extended to the and nm node, and the lithography performance requirements need to be tightened further to enable this shrink. Next to generic scanner system improvements, application-specific solutions are needed to follow the requirements for critical dimension CD control and overlay. The application-specific solutions need a holistic optimization approach for the scanner, the mask, and the patterning process.
We will describe the holistic lithography systems architecture that enables dynamic use of high-order scanner optimization based on advanced actuators of projection lens and scanning stages. Next to the scanner system, key components of this architecture are an angle-resolved scatterometer to measure CD, overlay, and focus, and an off-tool computation server to calculate application-specific recipes for the scanner.
Based on real production wafer data, we will show the benefit for CD control, focus control, and overlay control, and demonstrate lithography performance levels required for and nm node production. Hotspot prevention and detection method using an image-recognition technique based on higher-order local autocorrelation. Although a number of factors relating to lithography and material stacking have been investigated to realize hotspot-free wafer images, hotspots are often still found on wafers.
For the nm technology node and beyond, the detection and repair of hotspots with lithography simulation models is extremely time-consuming. Thus, hotspots represent a critical problem that not only causes delays to process development but also represents lost business opportunities. In order to solve the time-consumption problem of hotspots, this paper proposes a new method of hotspot prevention and detection using an image recognition technique based on higher-order local autocorrelation, which is adopted to extract geometrical features from a layout pattern.
To prevent hotspots, our method can generate proper verification patterns to cover the pattern variations within a chip layout to optimize the lithography conditions. Moreover, our method can realize fast hotspot detection without lithography simulation models. Obtained experimental results for hotspot prevention indicated excellent performance in terms of the similarity between generated proposed patterns and the original chip layout patterns, both geometrically and optically.
Sidewall profile engineering for the reduction of cut exposures in self-aligned pitch division patterning. As nm immersion lithography will likely be required to be extended beyond nm half-pitch, multiple patterning lithography will become a necessity in that scenario. We present a cost-effective approach for double patterning with extendibility to subnm half-pitch division, which is a very promising candidate for advanced logic nodes. Spacers on sufficiently sloped sidewalls directly transferred from a low-contrast photoresist profile can be removed by anisotropic etching.
Alternatively, spacer gaps for defining trenches may be prevented from penetrating to the substrate by the use of sloped sidewalls. These sloped sidewalls are defined by attenuated phase-shift mask features, which impart phase shifts other than deg or 0 deg. Loop trimming and sidewall spacer definition are accomplished in a single photomask. In addition, there is now an extra ability to define random, arbitrary breaks in the spacer-defined pattern, without using an extra exposure for specified cuts. In this way, a single exposure using a modified attenuated phase-shift photomask, followed by a low-contrast development process around the sensitivity limit, is sufficient to pattern regularly arranged spacer-defined lines at fixed pitch while including some predetermined line cut locations.
The section includes outstanding new results in commercial research and development in photonics where micro-optics and MEMS are merged and innovative breakthrough devices come to light. High dynamic range digital micromirror device-based infrared scene projector. OPTRA is developing a next generation digital micromirror device DMD based two-band infrared scene projector IRSP with infinite bit depth independent of frame rate and an order of magnitude improvement in contrast over the state of the art.
Traditionally, DMD-based IRSPs have offered larger format, superior uniformity, and pixel operability relative to resistive and diode arrays. The source-conditioning DMD is operated in binary mode, and the relay optics that form the structured illumination act as a low-pass spatial filter. The structured illumination is, therefore, spatially grayscaled and more importantly is analog with no PWM. In addition, the structured illumination concentrates energy where bright objects will be projected and extinguishes energy in dark regions; the result is a significant improvement in contrast.
Resonant biaxial 7-mm MEMS mirror for omnidirectional scanning. Low-cost automotive laser scanners for environmental perception are needed to enable the integration of advanced driver assistant systems into all automotive vehicle segments, which is a key to reduce the number of traffic accidents on roads. Within the scope of the European-funded project MiniFaros, partners from five different countries have been cooperating in developing a small-sized low-cost time-of-flight-based range sensor.
An omnidirectional deg laser scanning concept has been developed based on the combination of an omnidirectional lens and a biaxial large aperture MEMS mirror. The concept, design, fabrication, and first measurement results of a resonant biaxial 7-mm gimbal-less MEMS mirror that is electrostatically actuated by stacked vertical comb drives is described. Identical resonant frequencies of the two orthogonal axes are necessary to enable the required circle scanning capability.
A tripod suspension was chosen, since it minimizes the frequency splitting of the two resonant axes. Digital micromirror device as a diffractive reconfigurable optical switch for telecommunication. Digital micromirror devices DMDs by their high-switching speed, stability, and repeatability are promising devices for fast, reconfigurable telecommunication switches.
However, their binary mirror orientation is an issue for conventional redirection of a large number of incoming ports to a similarly large number of output fibers, like with analog micro-opto electro-mechanical systems. We are presenting here the use of the DMD as a diffraction-based optical switch, where Fourier diffraction patterns are used to steer the incoming beams to any output configuration.
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Fourier diffraction patterns are computer-generated holograms that structure the incoming light into any shape in the output plane. This way, the light from any fiber can be redirected to any position in the output plane. The incoming light can also be split to any positions in the output plane. Wavefront control in space with MEMS deformable mirrors for exoplanet direct imaging.
Deformable mirrors DMs are a key element of a wavefront control system, as they correct for imperfections, thermal distortions, and diffraction that would otherwise corrupt the wavefront and ruin the contrast. The goal of the CubeSat DM technology demonstration mission is to test the ability of a microelectromechanical system MEMS DM to perform wavefront control on-orbit on a nanosatellite platform. We consider two approaches for an MEMS DM technology demonstration payload that will fit within the mass, power, and volume constraints of a CubeSat: 1 a Michelson interferometer and 2 a Shack-Hartmann wavefront sensor.
We clarify the constraints on the payload based on the resources required for supporting CubeSat subsystems drawn from subsystems that we have developed for a different CubeSat flight project. We discuss results from payload laboratory prototypes and their utility in defining mission requirements. Three-dimensional profiling using a still shot. Mahesh Kondiparthi. The proposed method uses an amplitude-modulated Ronchi grating, which allows one to extract phase and unwrap the same with a single image. Ronchi equivalent image can be derived from modified grating image, which aids in extracting wrapped phase using Fourier transform profilometry.
The amplitude of the modified grating aids in phase unwrapping. As we only need a projector that projects an amplitude-modulated grating, the proposed method allows one to extract three-dimensional profile without using full video projectors. This article also deals with noise reduction algorithms for fringe projection techniques. Cryogenic testing of a unimorph-type deformable mirror and theoretical material optimization. The testing of a lightweight unimorph-type deformable mirror DM for wavefront correction in cryogenic instruments is reported.
The presented mirror manufactured from the titanium alloy TiAl6V4 with a piezoelectric disk actuator was cooled to 86 K and characterized for thermally induced deformation and the achievable piezoelectric stroke between room temperature and 86 K. Through a finite element analysis, we obtained a first approximation in determining the exact temperature-dependent coefficient of thermal expansion CTE of the piezo material PIC These investigations will enable the improvement of the athermal design of a unimorph-type DM.
Full-frame programmable spectral filters based on micromirror arrays. Steven Love , David Graff. Such a device is created by placing a DMD at the spectral plane of an imaging spectrometer and by using it as a spectral selector that passes some wavelengths down the optical train to the final image and rejects others.
Although simple in concept, realizing a truly practical DMD-based spectral filter has proved challenging. Versions described to date have been limited by the intertwining of image position and spectral propagation direction common to most imaging spectrometers, reducing these instruments to line-by-line scanning imagers rather than true spectral cameras that collect entire two-dimensional 2-D images at once.
Here, we report several optical innovations that overcome this limitation and allow us to construct full-frame programmable filters that spectrally manipulate every pixel, simultaneously and without spectral shifts, across a full 2-D image. So far, our prototype, which can be programmed either as a matched-filter imager for specific target materials or as a fully hyperspectral multiplexing Hadamard transform imager, has demonstrated over programmable spectral bands while maintaining good spatial image quality.
We discuss how diffraction-mediated trades between spatial and spectral resolution determine achievable performance. Polygonal pyramidal reflector-based micromachined microscanners for bioimaging. Senthil Kumar , Fook Siong Chau. In order to alleviate problems arising from the dynamic deformation of thin microelectromechanical systems MEMS micromirrors and to realize full circumferential scanning FCS that is highly desired in some clinic applications, such as gastrointestinal and intravascular investigations, three prototypes of polygonal pyramidal reflector-based MEMS microscanners have been developed and are described.
The cascaded chevron-beam electrothermal actuator, comb-drive electrostatic actuator with double T-shaped spring mechanism, and comb-drive electrostatic actuator with resonating mechanism were investigated in detail as a means to drive a polygonal microreflector. The polygonal microreflector, which has multiple facets on its surface, was fabricated through a route involving KOH wet-etching processing and diamond-turning soft lithography technologies. The assembly process of the actuators and the microreflector is also presented. A peak scanning speed up to Hz and a maximum optical scanning angle of deg were achieved by the electrostatic-resonating MEMS microscanner.
In-plane external fiber Fabry—Perot cavity comprising silicon micromachined concave mirror. Light trapping in optical cavities has many applications in optical telecommunications, biomedical optics, atomic studies, and chemical analysis. Efficient optical coupling in these cavities is an important engineering problem that affects greatly the cavity performance. Reported in-plane external fiber Fabry—Perot cavities in the literature are based on flat micromachined mirrors.
In this case, the diffraction loss in the cavity is usually overcome by using an expensive-lensed fiber or by inserting a coated lens in the cavity leading to a long cavity with a small free spectral range. In this work, we report a Fabry—Perot cavity formed by a multilayer-coated cleaved-surface single-mode fiber inserted into a groove while facing a three-dimensional concave micromirror; both are fabricated by silicon micromachining.
The light is trapped inside the cavity while propagating in-plane of the wafer substrate. Theoretical modeling is carried out, taking into account the effect of asymmetry in the mirror radii of curvature resulting from the micromachining process. The presented cavity has a measured line width of 0. Toward real-time spectral imaging for chemical detection with a digital micromirror device-based programmable spectral filter.
David Graff , Steven Love. Hyperspectral imaging sensors have proven to be powerful tools for highly selective and sensitive chemical detection applications, but they have significant operational drawbacks including slow line-scanning acquisition, large data volume of the resulting images, and a detection time lag due to the computational overhead of the matched-filter analysis. Based on traditional optical techniques, our spectral filter encodes the spectral information orthogonal to the spatial image information, enabling the DMD to encode matched-filter information into the spectral content of the scene without disturbing the underlying 2-D image.
With this new technology, everything from simple multiband filters to very complicated hyperspectral matched filters can be implemented directly in the optical train of the sensor, producing an image highlighting a target signature within a spectrally cluttered scene in real time without further processing. We will also show examples of multispectral and hyperspectral matched-filter images recorded with our visible spectrum prototype.
Development of a focusing micromirror device with an in-plane stress relief structure in silicon-on-insulator technology. A new design concept for a dynamically focusing silicon membrane mirror with 6-mm diameter and electrostatic actuation was realized. With this concept, membrane buckling by residual compressive stress inside the membrane can be avoided, which is observed even in crystalline membranes fabricated in silicon-on-insulator SOI technology and leads to severe distortion of stress-sensitive devices, such as membrane-based micromirrors.
To eliminate the influence of residual stress compressive or tensile , a membrane suspension with a new stress-relief design was developed by the use of finite element FEM simulations. Measurements of realized devices are in very good agreement with the prediction of the FEM simulation. A focus range between 97 mm and infinity flat position can be used in accordance with the simulation. Investigation of diffraction-based measurement errors in optical testing of aspheric optics with digital micromirror devices. Stephan Stuerwald , Robert Schmitt. Spatial light modulators SLMs have shown to be versatile tools for displays, but also for various applications in optical metrology since light can be individually directed and customized and thus they may serve as flexible masks or holograms.
Here, we present and compare different approaches for simulating the diffractive pattern when applying a micromirror device for wavefront readout. The different simulation methods for calculating the diffraction pattern are based on Monte-Carlo simulations in combination with nonsequential ray tracing, on Fourier optics methods Fourier transform, FT and on complex digital holographic wavefront propagation. The wavefront measurement concept with the DMDs is based on selecting single subapertures of the wavefront under test and on measuring the wavefront slope consecutively in a scanning procedure.
In contrast, in LCD-based approaches already shown in literature, the selection of subapertures and thus the scanning procedure is performed in transmission. The measurement concept and diffraction-based measurement errors of this method will be demonstrated for aspheric optics. Furthermore, different approaches for the prediction and reduction of the diffractive pattern—also based on holographic complex wave front propagation—will be described and characterized. Quasistatic microscanner with linearized scanning for an adaptive three-dimensional laser camera. This paper reports on a gimbaled MEMS scanning mirror with quasistatic resonant actuation, specially developed for adaptive raster scanning in an innovative three-dimensional 3-D time-of-flight ToF laser camera with real-time foveation.
This mirror is 2. For position feedback, piezo-resistive position sensors are integrated on chip for both axes. Flatness-based open loop control is used for driving control of quasistatic axis in order to compensate for the dynamics of the low damped MEMS system. A translatory MOEMS actuator with extraordinary large stroke—especially developed for fast optical path length modulation in miniaturized Fourier transform infrared spectrometers FTSs —is presented.
A precise translational out-of-plane oscillation at Hz with large stroke of up to 1. Design and fabrication of Fabry—Perot filters for infrared hyperspectral imagers. Hyperspectral infrared imagers are of great interest in applications requiring remote identification of complex chemical agents. The combination of mercury cadmium telluride detectors and Fabry—Perot filters FPFs is highly desirable for hyperspectral detection over a broad wavelength range. The geometries of distributed Bragg reflector DBR -based tunable FPFs are modeled to achieve a desired spectral resolution and wavelength range.
Additionally, acceptable fabrication tolerances are determined by modeling the spectral performance of the FPFs as a function of DBR surface roughness and membrane curvature. These fabrication nonidealities are then mitigated by developing an optimized DBR process flow yielding high-performance FPF cavities suitable for integration with hyperspectral imagers. Alexander Starikov , Yi-Sha Ku. Three-dimensional integration of stacked device cells in front end FE and of advanced metallization in back end BE enabled by through-silicon via TSV opens new paths to increased product functionality even without device shrink.
Development of the new designs, manufacturing methods, and processes demands rapid technology and materials characterization, as well as in-line metrology and inspection for process development and control in completely new and changing applications environments. Site-specific metrology, inspection, and failure analysis of three-dimensional interconnects using focused ion beam technology. Frank Altmann , Richard Young. These technologies involve vertical die stacking or chip embedding with high-density interconnects and are based on combinations of process steps that come from formerly strictly separated technology areas.
Thus, there is an increasing need to understand a large number of different interface properties, to control and optimize processes, and to avoid defect formation that could affect reliability. This complexity, in terms of design, new materials, and material combinations, also requires the development of new failure analysis tools to support these developments. The application potential of a new fast plasma focused ion beam FIB system for metrology and failure analysis is demonstrated in several selected case studies.
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This makes the plasma-FIB a very attractive tool for the analysis of relatively large interconnect structures without any need for mechanical preparation steps. Potential challenges with managing mechanical stress and the consequent effects on device performance for advanced three-dimensional 3-D IC technologies are outlined. The growing need in a simulation-based design verification flow capable of analyzing a design of 3-D IC stacks and detecting across-die out-of-spec variations in MOSFET electrical characteristics caused by the die thinning and stacking-induced mechanical stress is addressed.
The development of a multiscale simulation methodology for managing mechanical stresses during a sequence of designs of 3-D IC dies, stacks, and packages is focused. A set of physics-based compact models for a multiscale simulation is proposed to assess the mechanical stress across the device layers in silicon chips stacked and packaged with the 2.
A calibration technique based on fitting to measured electrical characteristics of the test-chip devices is presented. Macroinspection methodology for through silicon via array in three-dimensional integrated circuit. We are developing a new macroinspection technology for through silicon via TSV process wafers. We present new simulation results obtained with a fine TSV model and new optics.
The optical system includes not only diffraction optics, but also polarization optics, by which we can detect changes in the profile cross-sectional shape of repeated patterns by detecting changes in the polarization status of reflected light.
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Multiwavelength Raman characterization of silicon stress near through-silicon vias and its inline monitoring applications. Characterization of silicon stress near copper Cu -filled through-silicon via s TSVs was demonstrated using high-resolution micro-Raman spectroscopy. For depth profiling of Si stress distribution near TSVs, a polychromator-based, multiwavelength excitation Raman measurement with different probing depths was used.