Polymeric membranes for gas separation are limited in their performance by a trade-off between permeability and selectivity. New methods of design are necessary in making membranes, which can show both high permeability and selectivity. A mixed matrix membrane is one such particular design, which brings in the superior gas separation performance of inorganic membranes together with the easy processability and price of the polymers. In a mixed matrix membrane, the inorganic phase is dispersed in the polymeric continuous phase. Nanocomposite membranes have a more sophisticated design with a thin separation layer on top of a porous support. The objective of this research was to fabricate thin SWNT nanocomposite membranes for gas separation, which have both high permeability and selectivity. SWNT/polyacrylic nanocomposite membranes were fabricated by orienting the SWNTs by high vacuum filtration. The orientation of SWNTs on top of the porous support was sealed by UV polymerization. For making these membranes, the CNTs were purified and cut into small open tubes simultaneously functionalizing them with COOH groups. Gas sorption of CO2 in COOH functionalized SWNTs was lower than in purified SWNTs. Permeabilities in etched membrane were higher than Knudsen permeabilities by a factor of 8, and selectivities were similar to Knudsen selectivities. In order to increase the selectivities, SWNTs were functionalized with zwitterionic functional groups. Gas sorption in zwitterion functionalized SWNTs was very low compared to in COOH functionalized SWNTs. This result showed that the zwitterionic functional groups are kinetically blocking the gas molecules from entering the pore of the CNT. SWNT/polyamide nanocomposite membranes were fabricated using the zwitterion functionalized SWNTs by interfacial polymerization. The thickness of the separation layer was around 500nm. Gas permeabilities in the CNT membranes increased with increasing weight percentage of the SWNTs. Gas permeabilities were higher in COOH SWNT membrane than in zwitterion SWNT membrane. Gas selectivities were similar to the Knudsen selectivities, and also to the intrinsic selectivities in the pure polyamide membrane. The water flux in SWNT-polyamide membranes increased with increasing weight percentage of zwitterion functionalized SWNTs, along with a slight increase in the salt rejection. Membranes exhibited less than 1% variability in its performance over three days. / Ph. D.

Gallium nitride (GaN) and its related semiconductor alloys are attracting tremendous interest for their wide range of applications in blue and green LEDs, diode lasers, high-temperature and high-power electronics. Nanomaterials such as InGaN/GaN core-shell three-dimensional nanostructures are seen as a breakthrough technology for future solid-state lighting and nano-electronics devices. In a core-shell LED, the active semiconductor layers grown around a GaN core enable control over a wide range of wavelengths and applications. In this thesis the capability for the heteroepitaxial growth of a proof-of-principle core-shell LED is advanced. A design that can be applied at the wafer scale using metalorganic vapor phase epitaxy (MOVPE) crystal growth on highly uniform GaN nanorod (NR) structures is proposed. This project demonstrates understanding over the growth constraints of active layers and dopant layers. The impact of reactor pressure and temperature on the morphology and on the incorporated InN mole fraction was studied for thick InGaN shells on the different GaN crystal facets. Mg doping and effectiveness of the p-n junction for a core-shell structure was studied by extensive growth experiments and characterization. Sapphire and Si substrates were used, and at all the stages of growth and fabrication. The structures were optimized to achieve geometry homogeneity, high-aspect-ratio, incorporation homogeneity for InN and Mg dopant. The three-dimensional nature of NRs and their light emission provided ample challenges which required adaptation of characterization and fabrication techniques for a core-shell device. Finally, an electrically contacted core-shell LED is demonstrated and characterized. Achieving a proof-of-principle core-shell device could be the starting point in the development of nanostructure-based devices and new physics, or in solving technical problems in planar LEDs, such as the polarization of emitted light, the quantum-confined Stark effect, efficiency droop, or the green gap.

Les copolymères à bloc (BCP) ont la propriété particulière de s’auto-assembler en structures périodiques. Ces macromolécules en association avec la photolithographie est un candidat prometteur à utiliser comme technique alternative pour les patterning avancé de très haute résolution. De cette façon, la réduction des circuits intégrés peut être maintenue. Les BCPs avec une forte incompatibilité chimique entre les deux blocs présentent une valeur élevée du paramètre d’interaction de Flory-Huggins χ. La théorie des BCPs prédit des caractéristiques périodiques de seulement quelques nanomètres avec des BCPs à haut valeur d’interaction.Cette thèse présente un dispositif expérimental en vue du développement d’une lithographie à BCPs de deuxième génération en utilisant le polystyrène-bloc polydiméthylsiloxane (PS-b-PDMS), contre le polystyrène-bloc-Polydi(méthyle méthacrylate) (PS-b-PMMA) à faible valeur de χ. Sur ce sujet, la cinétique d’auto-assemblage d’un PS-b-PDMS avec une valeur du paramètre de segregation χN élevée a été amélioré avec le mélange de plastifiants sélectifs au bloc PS. L’auto-assemblage sur des grandes surfaces a été alors prouvé par un recuit thermique rapide (~ 30 s). Comme une preuve de concept de la lithographie, certains masques PS-b-PDMS testés ont été transférés sur Si, où des caractéristiques allant jusqu’à 25 nm ont été atteintes.Le principe de la lithographie par BCP a également été utilisé pour montrer la structuration de matériaux 2D. Par exemple, le graphène présente un besoin réel de structuration en nanostructures très étroites afin d’ouvrir un gap entre la bande de valence et la bande conduction pour modifier ses propriétés électriques par confinement quantique.Un bas Le PS-b-PDMS a été utilisé pour patterner avec de tailles caractéristiques de 10 nm. Le BCP est déposé par centrifugation et recuit directement sur le graphène.L’auto-assemblage sur de grandes surfaces (1 cm²) est réalisé en quelques minutes et le masque est ensuite transféré vers le graphène par gravure plasma à base d’oxygène, où dans une seule étape la matrice PS est éliminé, les cylindres PDMS oxydés et le graphène gravé. De grandes surfaces de nanorubans de 11 nm de largeur (GNR) ont été fabriquées par la lithographie de l’auto-assemblage du PS-b-PDMS. Un nettoyage au plasma H2 a également été effectué afin d’éliminer les contaminants organiques apparaissant lors des étapes de fabrication. Des techniques différentes pour l’analyse du carbone telles que la spectroscopie photoélectronique de rayons X, la spectroscopie Raman et la microscopie à force atomique ont été utilisées pour montrer la haute qualité des GNR.La caractérisation électrique des GNRs tels que la mobilité et l’ouverture du gap dans le graphène ont également été mesurés pour confirmer le comportement électronique des nanorubans de graphène. Des valeurs de l’ordre de 150 cm²/V s et 30 meV ont été mesurées. L’ensemble de la procédure expérimentale a été réalisé dans le cadre des réglèmentations de salles blanches pour la microélectronique, puis les processus d’auto-assemblage des BCPs proposés sont évolutifs et peu coûteux et sont bien adaptés pour être intégrés aux techniques existantes de fabrication de semi-conducteurs. / The Block copolymers (BCPs) have the particular property of self-assemble into ordered periodical structures. These macromolecules in association with the classic photolithography, is a promising candidate to be used as an alternative technique for the advanced patterning. This way, the downsizing of the integrated circuits can be kept up. BCPs with high chemical incompatibility between their blocks exhibit a high value of the Flory-Huggins interaction parameter χ. The BCP theory predicts periodical features sizes with high-χ; BCPs of only few nanometers.The BCP lithography principe was also used to show the patterning of 2D materials. For exemple, graphene present a real needs of patterning into very narrow nanostructures to open up a bandgap to switch its electrical properties by quantum confinement. A low χN PS-b-PDMS was used to pattern ~ 10 nm features. BCP is spin-coated and annealed directly on graphene. Self-assembly on large surfaces (1 cm²) is achieved in few minutes and the mask is then transferred on graphene by oxygen-based plasma etching, where in a single step will eliminate the PS matrix, oxidized the PDMS cylinders and etch the graphene. Large surfaces of 11nm-width Graphen nanoribbons (GNRs) were fabricated by the self-assembly of PS-b-PDMS. Dry H2 plasma cleaning was also performed to remove organic contaminants appearing during the fabrication steps. Different analysis techniques of carbon such as Raman and X-ray photoelectron spectroscopy and atomic force microscopy were used to show the high chemical quality of the GNRs.Electrical characterization of the GNRs such as mobility and the bandgap openingin graphene were measured also to confirm the electronic behavior of the graphene nanoribbons. Values of the order of 150 cm²/V s and 30 meV were measured. The entire procedure was realized under microelectronics clean room requirement, then, the BCP self-assembly processes proposed are scalable and low cost, and is well-suited for integration with existing semiconductor fabrication techniques.The lithographical procedure developed in this investigation could also be generalized to fabricate different graphene nanostructures such as graphene nanomeshes or quantum dots that could be envisaged for other applications in functional devices. GNRs on large surfaces are expect to find a broad ranges of applications, in the fields of electrochemical and bioanalysis.

GaN nanopore arrays with pore diameters of approximately 75 nm were fabricated by inductively coupled plasma etching (ICP) using anodic aluminum oxide (AAO) films as etch masks. Nanoporous AAO films were formed on the GaN surface by evaporating an Al film onto a GaN epilayer and subsequently anodizing the aluminum. To minimize plasma-induced damage, the template was exposed to CF4-based plasma conditions. Scanning electron microscopy (SEM) analysis shows that the diameter and the periodicity of the nanopores in the GaN were directly transferred from the original anodic alumina template. The pore diameter in the AAO film can be easily controlled by tuning the anodization conditions. Atomic force microscopy (AFM), photoluminescence (PL) and micro-Raman techniques were employed to assess the quality of the etched GaN nanopore surface. Such a cost-effective method to produce nano-patterned GaN template would be useful for growth and fabrication of III-Nitrides based nanostructures and photonic band gap materials. / Singapore-MIT Alliance (SMA)

This research discusses the design, fabrication, integration, and characterization of micromachined millimeter-wave components and a signal source for THz multiplier source using the deep reactive ion etching technique. A wide range of advanced micromachined millimeter-wave components are proposed and fully validated with the measurement. These micromachined millimeter-wave passives include: the W-band straight and meander waveguides, W-band three-pole filter, waveguide hybrid and power divider, a novel CPW-to-waveguide transition and filter, and a novel cavity resonator for 60-GHz reconfigurable applications. The proposed THz multiplier source is a broadband 900-GHz silicon micromachined two-anode frequency tripler with the state-of-the-art performance. The research results enable the silicon micromachining technique to build low-loss and low-cost millimeter-wave components and THz signal sources.

Submitted by Milena Rubi (milenarubi@ufscar.br) on 2017-08-16T16:54:47Z No. of bitstreams: 1 CAMARGO_Janine_2017.pdf: 19878018 bytes, checksum: 517c1918bf6801b10fe87b0d806d8a50 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2017-08-16T16:55:38Z (GMT) No. of bitstreams: 1 CAMARGO_Janine_2017.pdf: 19878018 bytes, checksum: 517c1918bf6801b10fe87b0d806d8a50 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2017-08-16T16:55:44Z (GMT) No. of bitstreams: 1 CAMARGO_Janine_2017.pdf: 19878018 bytes, checksum: 517c1918bf6801b10fe87b0d806d8a50 (MD5) / Made available in DSpace on 2017-08-16T16:55:50Z (GMT). No. of bitstreams: 1 CAMARGO_Janine_2017.pdf: 19878018 bytes, checksum: 517c1918bf6801b10fe87b0d806d8a50 (MD5) Previous issue date: 2017-03-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Cellulose is a biopolymer available in abundance in nature, which presents very interesting properties mainly for the textile, packaging and paper industry. However, due to its strongly hydrophilic character, resulting from the presence of a large number of free hydroxyl groups in its molecule, its use in certain areas becomes limited. In order to promote the modification of the wetting characteristic of the cellulose, and make it superhydrophobic, samples of this material were submitted to plasma processes performed in two steps: ablation and film deposition. Initially, the effect of variation of ablation time on the creation of adequate surface topography was studied. For this, the samples were exposed to the oxygen plasma at a pressure of 13 Pa and power of 150 W, varying the treatment time from 5 to 60 minutes. Then, the treated samples were submitted to the process called PECVD (Plasma Enhanced Chemical Vapor Deposition), in which a film was deposited on the surface from the precursor hexamethyldisiloxane (HMDSO) in the presence of argon, in a ratio of 70 e 30%, respectively. The deposition time was set to 30 minutes and the power applied was 150 W. In a second investigation, the effect of the thickness of the deposited film was studied. In this case, the cellulose samples were previously exposed to the oxygen ablation plasma for 60 minutes and then led to the PECVD process, with the deposition time varying from 5 to 30 minutes. In a third investigation, the duration of the ablation and deposition steps was reduced to 30 and 1 minute, respectively, in order to optimize the methodology. The samples were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), profilometry, static contact angle measurements and hysteresis and sliding angle measurements. The results demonstrated that longer exposure times for the ablation step provide a significant modification in the material, through the creation of nanoscale structures on the surface of the fibers. The deposition step promoted the formation of films with organosilicon character on the cellulose surface, with thicknesses varying between 144 and 910 nm. The combination of the topography created after 30 minutes of ablation with the thin film resulting from the deposition step for 1 minute provided a surface with low receptivity for both polar (? = 150°) and nonpolar (? ~ 120°) liquids, whose wettability property remained stable with treatment aging time. The low values obtained for hysteresis (9°) and sliding angle (7°) confirm the creation of a superhydrophobic roll-off surface. / A celulose é um biopolímero disponível em abundância na natureza e que possui propriedades bastante interessantes principalmente para a indústria têxtil, de embalagens e papel. No entanto, devido ao seu caráter fortemente hidrofílico, proveniente da presença de um grande número de grupos hidroxila livres em sua molécula, sua utilização em determinadas áreas se torna limitada. Com o objetivo de promover a modificação da característica de molhabilidade da celulose, de modo a torná-la superhidrofóbica, amostras deste material foram submetidas a processos a plasma realizados em duas etapas: ablação e deposição de filme. Inicialmente, estudou-se o efeito da variação do tempo de ablação na criação da topografia adequada da superfície. Para isto, as amostras foram expostas ao plasma de oxigênio a uma pressão de 13 Pa e 150 W de potência, variando-se o tempo de tratamento de 5 a 60 minutos. Em seguida, as amostras tratadas foram submetidas ao processo denominado PECVD (Plasma Enhanced Chemical Vapor Deposition), no qual foi depositado um filme sobre a superfície das mesmas, a partir do precursor hexametildisiloxano (HMDSO) na presença de argônio, numa proporção de 70 e 30%, respectivamente. O tempo de deposição foi fixado em 30 minutos e a potência aplicada foi de 150 W. Numa segunda investigação, foi estudado o efeito da espessura do filme depositado. Neste caso, as amostras de celulose foram previamente expostas ao plasma de ablação com oxigênio durante 60 minutos e posteriormente ao processo de PECVD, variando-se o tempo de deposição de 5 a 30 minutos. Numa terceira investigação, o tempo de duração das etapas de ablação e deposição foi reduzido para 30 e 1 minuto, respectivamente, com o intuito de otimizar a metodologia. As amostras foram caracterizadas por Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Energia Dispersiva (EDS), Espectroscopia de Absorção no Infravermelho por Transformada de Fourier (FTIR), perfilometria, medição de ângulo de contato estático e medição de histerese e ângulo de deslizamento. Os resultados demonstraram que maiores tempos de exposição à etapa de ablação proporcionam uma modificação significativa no material, por meio da criação de estruturas em nanoescala na superfície das fibras. A etapa de deposição promoveu a formação de filmes de caráter organosilicone sobre a superfície da celulose, com espessuras variando entre 144 e 910 nm. A combinação entre a topografia criada após 30 minutos de ablação e o filme de menor espessura resultante da etapa de deposição durante 1 minuto, possibilitaram a obtenção de uma superfície de baixa receptividade tanto a líquidos polares (? =150°) quanto apolares (? ~120°), cuja propriedade de molhabilidade se manteve estável com o tempo de envelhecimento. Os baixos valores de histerese (9°) e ângulo de deslizamento (7°) obtidos confirmam a criação de uma superfície superhidrofóbica do tipo “roll-off”.

Du fait de la réduction des dimensions en microélectronique, les procédés de gravure par plasmas ne peuvent plus satisfaire aux exigences de l'industrie. De nouvelles stratégies sont en cours de développement. Ce travail consiste en l'étude de plasmas pulsés de HBr/O2 comme une alternative pour la gravure du silicium. Divers diagnostics dans un réacteur industriel 300 mm sont utilisés pour caractériser le plasma tandis que la gravure du silicium est étudiée par XPS et par microscopie électronique. Lorsque le plasma est pulsé à faible rapport cyclique, sa température et sa dissociation sont fortement réduits. Le flux de Br radicalaire par rapport à la période ON du plasma augmente tandis que l'influence du radical O diminue, ce qui conduit à une amélioration de la sélectivité par rapport au SiO2 et à une gravure plus homogène. Les profils des structures gravées peuvent être contrôlés par la formation de la couche de passivation sur les flancs dépendant également du rapport cyclique. / The continuous downscaling in microelectronics imposes increasing demands on the plasma processes and traditional ways for process optimization reach their limits. New strategies are needed and innovations in the field of plasma processes are being developed: e.g. the use of pulsed plasmas. In this thesis, a pulsed HBr/O2 etch plasma is studied. Various in-situ diagnostics are used to characterize pulsed plasmas in an industrial 12” etch reactor. The silicon etching is investigated by XPS and electron microscopy. We show that the plasma dissociation and temperature are reduced if the plasma is pulsed at low duty cycles. The Br radical flux with respect to the on-time of the plasma is increased and the influence of the O radical is decreased, leading to enhanced time compensated silicon etch rates, a higher selectivity towards SiO2 and a more homogeneous etching. The pattern profiles can be controlled via the sidewall passivation layer formation that is closely linked to the duty cycle.

III-V semiconductors are compounds made of elements from groups III and V of the periodic table. Most of these materials exhibit a direct bandgap, which makes them suitable for light emission and detection. Furthermore, ternary and quaternary III-V semiconductors offer some freedom in adjusting their material compositions, which also allows one to modify their bandgap energies, refractive indices, and other optical properties. This quality makes such materials suitable for the monolithic integration of laser sources with passive optical devices and detectors on a single chip. For example, such integration is used in indium phosphide (InP) technology for large-scale photonic integration in optical communication networks. Commercial integrated photonic circuits' functionality can be augmented by the implementation of nonlinear optical devices, enabling all-optical signal processing, frequency conversion, and on-chip sources of quantum light. This doctoral thesis focuses on design, fabrication, and testing of passive optical components based on III-V semiconductors. We explored various fabrication approaches for III-V nonlinear photonic devices. Among the III-V semiconductor platforms used in nonlinear photonics, we focused on AlGaAs as the most studied nonlinear optical platform, and InP and its quaternary derivatives as the most commercially developed platform. The fabrication processes for III-V photonic devices usually require the deposition of silica and chromium layers, and then three etch steps to etch the chromium, silica, and, finally, the III-V layer. In the thesis, we demonstrate a process which allows one to eliminate the chromium deposition and the associated etch step, thereby reducing the process complexity. We implemented this newly developed hard-mask process for etching numerous AlGaAs and InP photonic devices. This work was not only an important contribution to the University of Ottawa's cleanroom facility. The shared recipe can be used to recreate etch recipes for silica using soft masks like ZEP520a, PMMA, etc., at other similar university and research facilities around the world. The silica mask created using this process was later used to fabricate InP/InGaAsP-based half-core-etched and nanowire waveguides, which were used to perform the first reliable measurement of the nonlinear refractive index coefficient n₂ of InGaAsP/InP waveguides. We explored improved fabrication processes for AlGaAs waveguides, photonic crystals, and ring resonators. InP-based integrated optical devices are relatively difficult to fabricate because the etch byproducts are only volatile at elevated temperatures. Using a silica mask, we developed a very smooth etching process for InP waveguides with aspect ratios greater than 1:10. Suspended waveguide structures, where the guiding layer is surrounded by the air, are of great interest as they can exhibit large refractive index contrast for superior compactness and for achieving high intensity at low optical powers. We demonstrated fabrication process flows for creating suspended air-bridge structures in a 500-nm AlGaAs slab, which can be used in mid-IR sensing applications. The processes developed as part of this project cover a wide range of AlGaAs passive photonic devices such as waveguides, photonic crystals and ring resonators. Additionally, we demonstrated plasma etching selectivity improvements for AlGaAs etching using only a soft ZEP mask and were able to achieve a selectivity of 1:2.9. All these developments can be beneficial to other researchers working on III-V photonic devices. We also completed the first theoretical study of third-harmonic generation in dispersion-engineered AlGaAs suspended photonic crystal waveguide. Most importantly, we introduced a reliable and efficient method for modelling higher-order modes in photonic crystal waveguides that is less computationally intensive and far more accurate compared to the 3D FDTD method. We also experimentally demonstrate guided modes lying above the light line in AlGaAs photonic crystal waveguides. In one of the addition projects, we experimentally demonstrate third-harmonic generation (THG) in Silicon Nitride waveguides. In summary, this thesis presents details of the design and testing of different passive nonlinear III-V semiconductor photonic devices. In addition, this thesis presents the fabrication processes which can be used to reliably and repeatably fabricate photonic devices in these materials.

Résumé : Le transistor monoélectronique (SET) est un dispositif nanoélectronique très attractif à cause de son ultra-basse consommation d’énergie et sa forte densité d’intégration, mais il n’a pas les capacités suffisantes pour pouvoir remplacer complètement la technologie CMOS. Cependant, la combinaison de la technologie SET avec celle du CMOS est une voie intéressante puisqu’elle permet de profiter des forces de chacune, afin d’obtenir des circuits avec des fonctionnalités additionnelles et uniques. Cette thèse porte sur l’intégration 3D monolithique de nanodispositifs dans le back-end-of-line (BEOL) d’une puce CMOS. Cette approche permet d’obtenir des circuits hybrides et de donner une valeur ajoutée aux puces CMOS actuelles sans altérer le procédé de fabrication du niveau des transistors MOS. L’étude se base sur le procédé nanodamascène classique développé à l’UdeS qui a permis la fabrication de dispositifs nanoélectroniques sur un substrat de SiO2. Ce document présente les travaux réalisés sur l’optimisation du procédé de fabrication nanodamascène, afin de le rendre compatible avec le BEOL de circuits CMOS. Des procédés de gravure plasma adaptés à la fabrication de nanostructures métalliques et diélectriques sont ainsi développés. Le nouveau procédé nanodamascène inverse a permis de fabriquer des jonctions MIM et des SET métalliques sur une couche de SiO2. Les caractérisations électriques de MIM et de SET formés avec des jonctions TiN/Al2O3 ont permis de démontrer la présence de pièges dans les jonctions et la fonctionnalité d’un SET à basse température (1,5 K). Le transfert de ce procédé sur CMOS et le procédé d’interconnexions verticales sont aussi développés par la suite. Finalement, un circuit 3D composé d’un nanofil de titane connecté verticalement à un transistor MOS est réalisé et caractérisé avec succès. Les résultats obtenus lors de cette thèse permettent de valider la possibilité de co-intégrer verticalement des dispositifs nanoélectroniques avec une technologie CMOS, en utilisant un procédé de fabrication compatible. / Abstract : The single electron transistor (SET) is a nanoelectronic device very attractive due to its ultra-low power consumption and its high integration density, but he is not capable of completely replace CMOS technology. Nevertheless, the hybridization of these two technologies is an interesting approach since it combines the advantages of both technologies, in order to obtain circuits with new and unique functionalities. This thesis deals with the 3D monolithic integration of nanodevices in the back-end-ofline (BEOL) of a CMOS chip. This approach gives the opportunity to build hybrid circuits and to add value to CMOS chips without fundamentally changing the process fabrication of MOS transistors. This study is based on the nanodamascene process developed at UdeS, which is used to fabricate nanoelectronic devices on a SiO2 layer. This document presents the work done on the nanodamascene process optimization, in order to make it compatible with the BEOL of CMOS circuits. The development of plasma etching processes has been required to fabricate metallic and dielectric nanostructures useful to the fabrication of nanodevices. MIM junctions and metallic SET have been fabricated with the new reverse nanodamascene process on a SiO2 substrate. Electrical characterizations of MIM devices and SET formed with TiN/Al2O3 junctions have shown trap sites in the dielectric and a functional SET at low temperature (1.5 K). The transfer process on CMOS substrate and the vertical interconnection process have also been developed. Finally, a 3D circuit consisting of a titanium nanowire connected to a MOS transistor is fabricated and is functional. The results obtained during this thesis prove that the co-integration of nanoelectronic devices in the BEOL of a CMOS chip is possible, using a compatible process.

<p>The fabrication of zone plate lenses that are used for focusing X-rays relies on nanofabrication techniques such as e-beam lithography, reactive ion etching, and electroplating. The circular grating-like zone plate pattern can have a smallest half-period, a so-called zone width, of down to 20 nm while it also needs to have a height that is 5 to 10 times the zone width to have good diffraction efficiency. This high aspect ratio structuring is a very challenging field of nanofabrication.</p><p>This diploma project has focused on improving the process step of fabricating the electroplating mold by cryo-cooling the polymer during the reactive ion etching with O₂. The low temperature causes passivation of the sidewalls of the mold during etching which results in a more ideal rectangular profile of the high aspect ratio plating mold.</p><p>By etching at -100 °C, structures with highly vertical sidewalls and no undercut were realized. The experiments showed that there is a tradeoff between the anisotropy of the zone profile and the formation rate of polymer residue, so-called RIE grass. Through a proper choice of process parameters the grass could be completely removed without introducing any undercut.</p> / QC 20100414