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Design, Simulation and Characterization of Some Planar Lightwave CircuitsShi, Yaocheng January 2008 (has links)
Optical devices based on planar lightwave circuit (PLC) technology have the advantages of small size, high reliability, possibility for large scale production, and potential integration with electronics. These devices are widely employed in optical telecommunications, sensing, data storage, imaging, and signal processing. This thesis focuses on some selected PLC based devices, such as power splitters, demultiplexers, triplexers and polarization beam splitters. First, the basic principle of the waveguides and the simulation methods for PLC devices are discussed. A novel effective index method is introduced to reduce a two-dimensional structure to a one-dimensional one, and can be implemented for arbitrarily shaped waveguides. Numerical methods, such as finite-difference mode solver, beam propagation method, finite-difference time-domain method are introduced to analysis the mode profile of the waveguides, and the propagation properties of light in PLC devices. Multimode interference (MMI) couplers are widely used in many PLCs, such as power splitters, ring lasers, optical switches, and wavelength division multiplexers/demultiplexers. In this work, concepts for improving the self-imaging quality of MMI couplers are analyzed and new designs are proposed. A significant improvement in performance together with compact sizes were obtained with taper sections at the input/output of MMI couplers based on SOI, and deeply etched ridges in MMI couplers based on SiO2. A polarization insensitive dual wavelength demultiplexer based on sandwiched MMI waveguides was presented. Novel devices including triplexers and polarization beam splitters were realized by using photonic crystal (PhC) structures. Two stages of directional couplers based on PhC waveguides are cascaded to form an ultracompact triplexer. The special decoupling property of the PhC waveguide based directional coupler was utilized in the design. A novel polarization beam splitter was realized by combining a MMI coupler and a PhC which works as a polarization sensitive reflector. Finally, fabrication and optical characterization of an ultra-compact directional coupler and PhC structures in InP are presented. In a single etching step, by using the lag-effect in inductively coupled plasma reactive ion etching, a compact directional coupler (55 μm) is demonstrated. Carrier life times in PhC structures etched by chemically assisted ion beam etching were investigated, for emitter and switching applications. / QC 20100909
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Ion beam etching of InP based materialsCarlström, Carl-Fredrik January 2001 (has links)
<p>Dry etching is an important technique for pattern transferin fabrication of most opto-electronic devices, since it canprovide good control of both structure size and shape even on asub-micron scale. Unfortunately, this process step may causedamage to the material which is detrimental to deviceperformance. It is therefore an objective of this thesis todevelop and investigate low damage etching processes for InPbased devices.</p><p>An ion beam system in combination with hydrocarbon (CH<sub>4</sub>) based chemistries is used for etching. At variousion energies and gas flows the etching is performed in twomodes, reactive ion beam etching (RIBE) and chemical assistedion beam etching (CAIBE). How these conditions affect both etchcharacteristics (e.g. etch rates and profiles, surfacemorphology and polymer formation) and etch induced damage (onoptical and electrical properties) is evaluated and discussed.Attention is also paid to the effects of typical post etchingtreatments such as annealing on the optical and electricalproperties. An important finding is the correlation betweenas-etched surface morphology and recovery/degradation inphotoluminescence upon annealing in PH<sub>3</sub>. Since this type of atmosphere is typical forcrystal regrowth (an important process step in III/Vprocessing) a positive result is imperative. A low ion energy N<sub>2</sub>/CH<sub>4</sub>/H<sub>2</sub>CAIBE process is developed which not onlysatisfies this criteria but also exhibits good etchcharacteristics. This process is used successfully in thefabrication of laser gratings. In addition to this, the abilityof the ion beam system to modify the surface morphology in acontrollable manner is exploited. By exposing such modifiedsurfaces to AsH<sub>3</sub>/PH<sub>3</sub>, a new way to vary size and density of InAs(P)islands formed on the InP surfaces by the As/P exchangereaction is presented.</p><p>This thesis also proposes a new etch chemistry, namelytrimethylamine ((CH<sub>3</sub>)<sub>3</sub>N or TMA), which is a more efficient methyl sourcecompared to CH<sub>4</sub>because of the low energy required to break the H<sub>3</sub>C-N bond. Since methyl radicals are needed for theetching it is presumably a better etching chemistry. A similarinvestigation as for the CH<sub>4</sub>chemistry is performed, and it is found that bothin terms of etch characteristics and etch induced damage thisnew chemistry is superior. Extremely smooth morphologies, lowetch induced damage and an almost complete recovery uponannealing can be obtained with this process. Significantly,this is also so at relatively high ion energies which allowshigher etch rates.</p><p><b>Keywords:</b>InP, dry etching, ion beam etching, RIBE,CAIBE, hydrocarbon chemistry, trimethylamine, As/P exchangereaction, morpholoy, low damage, AFM, SCM, annealing</p>
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Development Of A Micro-fabrication Process Simulator For Micro-electro-mechanical-systems(mems)Yildirim, Alper 01 December 2005 (has links) (PDF)
ABSTRACT
DEVELOPMENT OF A MICRO-FABRICATION PROCESS SIMULATOR FOR MICRO-ELECTRO-MECHANICAL SYSTEMS (MEMS)
Yildirim, Alper
M.S, Department of Mechanical Engineering
Supervisor: Asst. Prof. Dr. Melik Dö / len
December 2005, 140 pages
The aim of this study is to devise a computer simulation tool, which will speed-up the design of Micro-Electro-Mechanical Systems by providing the results of the micro-fabrication processes in advance. Anisotropic etching along with isotropic etching of silicon wafers are to be simulated in this environment. Similarly, additive processes like doping and material deposition could be simulated by means of a Cellular Automata based algorithm along with the use of OpenGL library functions. Equipped with an integrated mask design editor, complex mask patterns can be created by the software and the results are displayed by the Cellular Automata cells based on their spatial location and plane. The resultant etched shapes are in agreement with the experimental results both qualitatively and quantitatively.
Keywords: Wet Etching, Anisotropic Etching, Doping, Cellular Automata, Micro-fabrication simulation, Material Deposition, Isotropic Etching, Dry Etching, Deep Reactive Ion Etching
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Hybrid-Lithography for the Master of Multi-ModeWaveguides NIL StampMistry, Akash, Nieweglowski, Krzysztof, Bock, Karlheinz 21 August 2024 (has links)
the presented work demonstrates the fabrication process of the master for nano-imprint lithography (NIL) stamp for multi-mode waveguide (MM-WG) with μ-mirror using hybrid-lithography, which includes a 2-photon-polymerization direct laser writing process (2PP-DLW) for μ-mirror surface and UV-photo lithography for MM-WGs. For the definition of the mirror surface at either end of waveguides in the master stamp, the 2PP-DLW process was used. It offers a lower surface roughness (< 0.1 λ) with fewer processing steps, alignment accuracy of ± 1 μm, prints fine and sharp contours, and relatively faster scanning for a specific material, which makes it the foremost technology over the traditional micro-mirror processes such as the dicing process, moving mask lithography, laser ablation, wet etching, and dry etching. For the fabrication of the waveguide core with rectangular cross-sections in the master stamp, UV mask exposure with SU-8 was used. It is a mass-production and low-cost technique. It gives a smooth structure with 90-degree sidewalls compared to other processes like dry etching, wet etching, mosquito method, and E-beam writing. We demonstrated the design and process of a master pattern with a density range from 0.04 to 0.2 to maintain equal pressure over the stamp in the NIL step for an almost uniform residual thickness layer.:Abstract
Introduction
Design of Experiments
Experimental Results and Discussions
Conclusion
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Contribution to the design and fabrication of an integrated micro-positioning system / Contribution à la conception et à la fabrication d'un système de micro-positionnement intégréKhan, Muneeb Ullah 24 March 2014 (has links)
L’objectif de la thèse est de développer un dispositif de micro positionnement intégrant à la fois les actionneurs et les capteurs. Un dispositif a été conçu afin de réaliser des déplacements dans les plans sur une course millimétrique. Le dispositif compact ne nécessite pas de système de guidage additionnel et selon le mode d’utilisation de ces moteurs, il est capable de réaliser des translations dans le plan ou des rotations autour d’un axe perpendiculaire au plan. Le dispositif comprend quatre moteurs électromagnétiques linéaires fixés orthogonalement sur une structure en forme de croix. Chaque moteur consiste en une paire de bobines planes entrelacées fixe et une barre ’aimants mobile. Un capteur de déplacement intégré dans la structure en croix permettant de mesurer le déplacement de celle-ci a été conçu et fabriqué. Ce capteur est constitué d’une tête de mesure à fibres optiques placé face à un réseau en silicium réalisé par des techniques de microfabrication. Afin de minimiser les erreurs d’assemblage, la structure en croix a également été micro fabriquée. Le dispositif est capable de réaliser un déplacement de 10 mm et une rotation de ±11° autour de l’axe perpendiculaire au plan du dispositif. La résolution de déplacement du dispositif est de 1,4 µm avec une précision de 31 nm en boucle fermée. Le dispositif peut également atteindre une vitesse de déplacement de 12 mm/s. / The objective of thesis is to develop an integrated micro positioning system for micro applications. A unique micro positioning system design capable to deliver millimeter level strokes with pre-embedded auto guidance feature in micro application has been realized. The design integrates, a stack of orthogonally arranged four electromagnetic linear motors. Each linear motor consists of a fixed planar electric drive coil and mobile permanent magnet array. The optimal design of the system delivers a small footprint size. In addition, to measure and control the displacement, a high resolution compact optical displacement measurement sensor has been designed and fabricated in silicon material using microfabrication technology. Furthermore, a light weight silicon cross structure was fabricated using dry etching technology to reduce components assembly errors. The device is capable to deliver 10 mm displacement stroke with a rotation of ±11° about an axis perpendicular to the plane of the device. The displacement resolution of the device is 1.4 µm with a precision of 31 nm in closed loop control. The device can realize displacement with a speed of 12 mm/s.
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Two-Dimensional Photonic Crystals in InP-based MaterialsMulot, Mikaël January 2004 (has links)
Photonic crystals (PhCs) are structures periodic in thedielectric constant. They exhibit a photonic bandgap, i.e., arange of wavelengths for which light propagation is forbidden.Engineering of defects in the PhC lattice offers new ways toconfine and guide light. PhCs have been manufactured usingsemiconductors and other material technologies. This thesisfocuses on two-dimensional PhCs etched in InP-based materials.Only recently, such structures were identified as promisingcandidates for the realization of novel and advanced functionsfor optical communication applications. The primary focus was on fabrication and characterization ofPhC structures in the InP/GaInAsP/InP material system. Thedemands on fabrication are very high: holes as small as100-300nm in diameter have to be etched at least as deep as 2µm. Thus, different etch processes had to be explored andspecifically developed for InP. We have implemented an etchingprocess based on Ar/Cl2chemically assisted ion beam etching (CAIBE), thatrepresents the state of the art PhC etching in InP. Different building blocks were manufactured using thisprocess. A transmission loss of 10dB/mm for a PhC waveguide, areflection of 96.5% for a 4-row mirror and a record qualityfactor of 310 for a 1D cavity were achieved for this materialsystem. With an etch depth of 4.5 µm, optical loss wasfound to be close to the intrinsic limit. PhC-based opticalfilters were demonstrated using (a) a Fabry-Pérot cavityinserted in a PhC waveguide and (b) a contra-directionalcoupler. Lag effect in CAIBE was utilized positively to realizehigh quality PhC taper sections. Using a PhC taper, a couplingefficiency of 70% was demonstrated from a standard ridgewaveguide to a single line defect PhC waveguide. During the course of this work, InP membrane technology wasdeveloped and a Fabry-Pérot cavity with a quality factorof 3200 was demonstrated. Keywords:photonic crystals, photonic bandgap materials,indium phosphide, dry etching, chemically assisted ion beametching, reactive ion etching, electron beam lithography,photonic integrated circuits, optical waveguides, resonantcavities, optical filtering, finite difference time domain,plane wave expansion.
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Two-Dimensional Photonic Crystals in InP-based MaterialsMulot, Mikaël January 2004 (has links)
<p>Photonic crystals (PhCs) are structures periodic in thedielectric constant. They exhibit a photonic bandgap, i.e., arange of wavelengths for which light propagation is forbidden.Engineering of defects in the PhC lattice offers new ways toconfine and guide light. PhCs have been manufactured usingsemiconductors and other material technologies. This thesisfocuses on two-dimensional PhCs etched in InP-based materials.Only recently, such structures were identified as promisingcandidates for the realization of novel and advanced functionsfor optical communication applications.</p><p>The primary focus was on fabrication and characterization ofPhC structures in the InP/GaInAsP/InP material system. Thedemands on fabrication are very high: holes as small as100-300nm in diameter have to be etched at least as deep as 2µm. Thus, different etch processes had to be explored andspecifically developed for InP. We have implemented an etchingprocess based on Ar/Cl<sub>2</sub>chemically assisted ion beam etching (CAIBE), thatrepresents the state of the art PhC etching in InP.</p><p>Different building blocks were manufactured using thisprocess. A transmission loss of 10dB/mm for a PhC waveguide, areflection of 96.5% for a 4-row mirror and a record qualityfactor of 310 for a 1D cavity were achieved for this materialsystem. With an etch depth of 4.5 µm, optical loss wasfound to be close to the intrinsic limit. PhC-based opticalfilters were demonstrated using (a) a Fabry-Pérot cavityinserted in a PhC waveguide and (b) a contra-directionalcoupler. Lag effect in CAIBE was utilized positively to realizehigh quality PhC taper sections. Using a PhC taper, a couplingefficiency of 70% was demonstrated from a standard ridgewaveguide to a single line defect PhC waveguide.</p><p>During the course of this work, InP membrane technology wasdeveloped and a Fabry-Pérot cavity with a quality factorof 3200 was demonstrated.</p><p><b>Keywords:</b>photonic crystals, photonic bandgap materials,indium phosphide, dry etching, chemically assisted ion beametching, reactive ion etching, electron beam lithography,photonic integrated circuits, optical waveguides, resonantcavities, optical filtering, finite difference time domain,plane wave expansion.</p>
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Top-down Fabrication Technologies for High Quality III-V NanostructuresNaureen, Shagufta January 2013 (has links)
III-V nanostructures have attracted substantial research effort due to their interesting physical properties and their applications in new generation of ultrafast and high efficiency nanoscale electronic and photonic components. The advances in nanofabrication methods including growth/synthesis have opened up new possibilities of realizing one dimensional (1D) nanostructures as building blocks of future nanoscale devices. For processing of semiconductor nanostructure devices, simplicity, cost effectiveness, and device efficiency are key factors. A number of methods are being pursued to fabricate high quality III-V nanopillar/nanowires, quantum dots and nano disks. Further, high optical quality nanostructures in these materials together with precise control of shapes, sizes and array geometries make them attractive for a wide range of optoelectronic/photonic devices. This thesis work is focused on top-down approaches for fabrication of high optical quality nanostructures in III-V materials. Dense and uniform arrays of nanopillars are fabricated by dry etching using self-assembly of colloidal SiO2 particles for masking. The physico-chemistry of etching and the effect of etch-mask parameters are investigated to control the shape, aspect ratios and spatial coverage of the nanopillar arrays. The optimization of etch parameters and the utilization of erosion of etch masks is evaluated to obtain desired pillar shapes from cylindrical to conical. Using this fabrication method, high quality nanopillar arrays were realized in several InP-based and GaAs-based structures, including quantum wells and multilayer heterostructures. Optical properties of these pillars are investigated using different optical spectroscopic techniques. These nanopillars, single and in arrays, show excellent photoluminescence (PL) at room temperature and the measured PL line-widths are comparable to the as-grown wafer, indicating the high quality of the fabricated nanostructures. The substrate-free InP nanopillars have carrier life times similar to reference epitaxial layers, yet an another indicator of high material quality. InGaAs layer, beneath the pillars is shown to provide several useful functions. It effectively blocks the PL from the InP substrate, serves as a sacrificial layer for generation of free pillars, and as a “detector” in cathodoluminescence (CL) measurements. Diffusion lengths independently determined by time resolved photoluminescence (TRPL) and CL measurements are consistent, and carrier feeding to low bandgap InGaAs layer is evidenced by CL data. Total reflectivity measurements show that nanopillar arrays provide broadband antireflection making them good candidates for photovoltaic applications. A novel post etch, sulfur-oleylamine (S-OA) based chemical process is developed to etch III-V materials with monolayer precision, in an inverse epitaxial manner along with simultaneous surface passivation. The process is applied to push the limits of top-down fabrication and InP-based high optical quality nanowires with aspect ratios more than 50, and nanostructures with new topologies (nanowire meshes and in-plane wires) are demonstrated. The optimized process technique is used to fabricate nanopillars in InP-based multilayers (InP/InGaAsP/InP and InP/InGaAs/InP). Such multilayer nanopillars are not only attractive for broad-band absorption in solar cells, but are also ideal to generate high optical quality nanodisks of these materials. Finally, the utility of a soft stamping technique to transfer free nanopillars/wires and nanodisks onto Si substrate is demonstrated. These nanostructures transferred onto Si with controlled densities, from low to high, could provide a new route for material integration on Si. / <p>QC 20130205</p>
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Εγκατάσταση και μελέτη αντιδραστήρα τεχνολογικού πλάσματος ραδιοσυχνοτήτων για εφαρμογές στη νανοτεχνολογίαΚονισπολιάτης, Χρήστος 13 October 2013 (has links)
Μια από τις σημαντικότερες τεχνικές εγχάραξης σε μίκρο και νάνο-κλίμακα είναι αυτή της ξηρής εγχάραξης με πλάσμα. Η παρούσα εργασία είχε σαν σκοπό την κατασκευή διάταξης επεξεργασίας ψυχρού πλάσματος χαμηλής πίεσης που να λειτουργεί στο πεδίο των ραδιοσυχνοτήτων, με την προοπτική να χρησιμοποιηθεί για την επεξεργασία πολυμερών και άλλων υλικών που χρησιμοποιούνται στις μονώσεις υψηλών τάσεων ώστε να βελτιωθούν διάφορες ιδιότητές τους όπως η επιφανειακή υδροφοβία και η αντοχή στη ρύπανση. Ειδικότερα:
Στο πρώτο κεφάλαιο γίνεται εισαγωγή του αναγνώστη στην επεξεργασία πλάσματος και συγκεκριμένα στην εγχάραξη και τους φυσικούς και χημικούς μηχανισμούς της. Αναλύεται η διάταξη RIE, η οποία εφαρμόζεται κατά την κατασκευή του συστήματος.
Στο δεύτερο κεφάλαιο περιγράφεται ο σχεδιασμός και η κατασκευή της διάταξης επεξεργασίας, η οποία αποτελείτε από διακριτά μέρη όπως οι θάλαμοι, το πνευματικό σύστημα, το αντλητικό σύστημα και το σύστημα τροφοδοσίας της ισχύος. Δόθηκε ιδιαίτερη προσοχή στη λεπτομερή περιγραφή του κάθε εξαρτήματος που ενσωματώθηκε και ο εξειδικευμένος ρόλος του, ενώ τα αναλυτικά κατασκευαστικά σχέδια παρατίθενται στο παράρτημα.
Στο τρίτο κεφάλαιο γίνεται βασικός χαρακτηρισμός του αντιδραστήρα. Δηλαδή, παρουσιάζονται οι ηλεκτρικές μετρήσεις οι οποίες ταυτίζονται με τη βιβλιογραφία, παρουσιάζονται οπτικές μετρήσεις από τις οποίες γίνεται ταυτοποίηση ενεργών σωματίων, τα οποία επίσης είναι σύμφωνα με τη βιβλιογραφία παρόμοιων συστημάτων και τέλος, γίνεται ενδεικτική επεξεργασία πολυμερούς και έλεγχος του αποτελέσματος, το οποίο είναι η πιστή απόδοση μοτίβου και ρυθμός εγχάραξης 30nm/min.
Στο τέταρτο και τελευταίο κεφάλαιο προτείνονται μελλοντικές εργασίες και βελτιώσεις. / One of the most prominent etching techniques at micro and nano-scale is dry plasma etching. This work’s purpose was the fabrication of a cold plasma low pressure radio-frequency processing rig, with the prospect of being used for polymer and other materials processing, that are used in high voltage insulators, in order to improve their surface properties such as hydrophobicity and pollution resistance. In particular;
In the first chapter the reader is being introduced in plasma processing and in particular in etching and physical and chemical mechanisms. RIE set-up, which is to be applied in our rig, is being analyzed.
In the second chapter the design and fabrication of the processing rig are being described, which includes parts like the chambers, the pneumatic system, the pumping system and the power delivery system. Special care has been given for a detailed description of every added component and its specialized role, while their analytical mechanical designs are collocated in the appendix.
In the third chapter a basic characterization of the reactor is being delivered. Namely, we present electrical measurements which correspond precisely to bibliography and we also present optical measurements from which identification of reactive species is derived, also in accordance to bibliography. Finally, a polymeric substrate is indicatively processed and the result is the faithful pattern transfer by an etching rate of 30nm/min.
In the fourth and last chapter, suggestions for future work and improvements are made.
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Nonlinear devices characterization and micromachining techniques for RF integrated circuitsParvais, Bertrand J. H. 10 December 2004 (has links)
The present work is dedicated to the development of high performance integrated circuits for wireless communications, by acting of three different levels: technologies, devices, and circuits.
Silicon-on-Insulator (SOI) CMOS technology is used in the frame of this work. Micromachining technologies are also investigated for the fabrication of three-dimensional tunable capacitors. The reliability of micromachined thin-film devices is improved by the coating of silanes in both liquid- and vapor-phases.
Since in telecommunication applications, distortion is responsible for the generation of spurious frequency bands, the linearity behavior of different SOI transistors is analyzed. The validity range of the existing low-frequency nonlinear characterization methods is discussed. New simple techniques valid at both low- and high-frequencies, are provided, based on the integral function method and on the Volterra series.
Finally, the design of a crucial nonlinear circuit, the voltage-controlled oscillator, is introduced. The describing function formalism is used to evaluate the oscillation amplitude and is embedded in a design methodology. The frequency tuning by SOI varactors is analyzed in both small- and large-signal regimes.
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