Miniaturization has become a product trend due to technological advancements, thus giving rise to nanoimprint lithography printing. Miniaturization is also a trend regarding process features. nanoimprint lithography has great potential for its simple process, low cost, mass-production capacity, and ease to produce nanoscale microstructure. After making a fence structure of line width less than 100nm on quartz glass with FIB, this study printed the fence structure of line width less than 100nm with the nanoimprint lithography using PDMS mold and quartz soft mold. Though PDMS molding is fast and convenient, it is uncommon with regard to small-size press. This study investigated the application of PDMS molds to nanoimprint lithography in order to verify the optimal parameters of PDMS molding and the results of nanoimprint lithography with PDMS soft modes. After obtaining the optimal molding press, the optimal molding parameters and press pressure were applied to find the optimal experimental results. Results show that the combination can successfully print a fence structure with a line width of 40nm.

Indiana University-Purdue University Indianapolis (IUPUI) / Infrared (IR) polarizers have been widely used in military and commercial applications. Controlling the polarization of incident light is one of major issues in the detector systems. However, conventional polarimetric IR detectors require series of polarizers and optical components, which increase the volume and weight of the system. In this research, stacked 1-dimensional (1-D) subwavelength grating structures were studied to develop compact size IR polarimetric detector by using surface plasmonic polariton. Experimental parameters were optimized by Finite Difference Time Domain (FDTD) simulation. Effects of gold (Au) grating size, numbers of stacked gratings, and dielectric space height were tested in the FDTD study. The fabrication of grating layers was conducted by using nanoimprint lithography. The samples were characterized by scanning electron microscopy. IR transmissions in transverse magnetic (TM) and transverse electric (TE) modes were measured by Fourier transform infrared spectroscopy (FTIR).

Durant la dernière décennie, la résonance de plasmon de surface (SPR) est devenue très populaire pour effectuer des analyses au cours d’un greffage chimique (ou biochimique) et étudier ainsi des réactions chimiques. Ce travail de thèse avait pour but de développer une méthode lithographique alternative, la nanoimpression assistée UV dite «douce», qui permet de fabriquer des réseaux de nanomotifs sur de très grandes surfaces (voir chapitre 1 - état de l’art) pour générer des nanostructures métalliques SPR intégrables. Les chapitres 2 et 3 étudient les paramètres expérimentaux de la nanoimpression pour obtenir des nanostructures hautement résolues et avec un minimum de défaut. Notre étude optique a été menée ensuite sur des réseaux de nanotrous imprimés dans des films d’or (chapitre 4). Le mécanisme physique du phénomène de transmission assistée par les plasmon est étudié de manière systématique d’après l’évolution de la position du pic de transmission avec les paramètres structuraux. Des mesures réalisées dans un système fluidique ont ensuite montré une réponse à un faible changement de l’indice de réfraction à la surface du réseau. Enfin, le dernier chapitre (chapitre 5) présente une nouvelle géométrie de biocapteurs optique basé sur une structure tri-couche dans une géométrie de type «nanocavité» à plasmon localisé (LSPR). Ces capteurs LSPR à nanocavités permettent d’améliorer le facteur de mérite d’un ordre de grandeur par rapport aux LSPR classiques. Leurs propriétés de résonance sont discutées à l’aide d’outils de simulation numérique. Enfin, nous démontrons qu’un tel capteur possède une grande sensibilité à la détection de biomolécules et serait donc adapté à l’étude d’interactions immunochimiques. / During the last decade, surface plasmon resonance (SPR) has become widely used to characterize a biological surface and to characterize binding events in the fields of chemistry and biochemistry. Research in this field has been favoured by the tremendous growth in nanofabrication methods among which soft lithographies are alternatively emerging. The purpose of this thesis work was to develop soft UV nanoimprint lithography, an emerging flexible technology allowing patterning on large area of subwavelength photonic nanostructures. The main advantages offered by soft UV nanoimprint lithography concern the simple patterning procedure and the low cost of the experimental setup (see state-of-art presented in chapter 1). Chapters 2 and 3 present the fabrication of master stamps, the study of nanoimprinting parameters coupled with the optimization of the etching process in order to get metallic nanostructures with limited pattern defects. The physical mechanisms of the transmission phenomenon exalted by surface plasmons were studied based on arrays of imprinted gold nanoholes (chapter 4). Extraordinary light transmission has been experimentally demonstrated. The geometrical effects on the position transmission peak were systematically analyzed. Proof-of-concept measurements performed in simple fluidic device indicate a response to small changes in refractive index in the surface vicinity. Finally, chapter 5 proposes a novel design for the optical sensor which is based on “nanocavities” exhibiting coupled localized plasmons. This LSPR sensor offers an improvement of one order of magnitude of the Figure of Merit compared to classical LSPR sensors. The resonance properties of these innovative nanocavities have been studied from numerical simulations and discussed based on their geometrical dependence. Since this system has demonstrated higher sensitivity for detection of biomolecules, it is thus fully adapted to study immunochemical binding interactions.

Three-dimensional (3D) polymer structures are very attractive because the extra structural dimension can provide denser integration and superior performance to accomplish complex tasks. Successful fabrication of 3D multilayer microstructures in thermoplastic polymers using optimized nanoimprint lithography techniques such as layer-transfer and transfer-bonding methods are developed in this dissertation work. The capability and flexibility of the techniques developed here are expected to have deep impact on the applications of soft materials such as polymers including functional polymers in micro- and nanofabricated devices and systems. Although NIL technique is developing rapidly in recent years, there are still issues that need to be addressed for broader adoption of the nanoimprint technique. One of the problems is the residual layer that remains in the polymer pattern after nanoimprint. The conventional approach, oxygen reactive-ion-etching (RIE) process, to remove the residual layers, increases the cost and lowers the overall throughput of the nanoimprint process. More severely, it can degrade or even damage the functional polymers. In order to overcome these problems, new residual layer removal techniques need to be developed. In this dissertation, two methods are newly developed, which do not negatively affect the chemistry of the polymer materials. The techniques are suitable for all thermoplastic polymers, particularly functional polymers. Another advantage of nanoimprint is its ability to directly create functional polymers structures. This is because thermal nanoimprint only needs temperature and pressure for pattern replication, which both are benign to functional polymers. This feature combined with newly developed techniques such as transfer-bonding and residue removal techniques opens up the possibilities in nondestructive functional polymers patterning at the micro- and nanoscale for novel applications in electronics, optoelectronics, photonics and bioengineering. Finally, several applications of 3D multilayer structures fabricated by the techniques developed in this dissertation are demonstrated. The first application is a multilayer metal-dielectric-metal structure with embedded microfluidic channels. This structure can be used as an on-chip tunable filter for integrated microfluidic applications. The second application is a multilayer microfluidic channels in which each layer has a different channel size. This device can be used for particle separation and filtration based on lateral fluid flow.

This thesis investigates technologies directed towards developing photonic crystal display devices. A switching technology based on dye electrophoretic motion within a 1D porous photonic crystal was developed. Dissociated absorbing dye species were moved through the assembled device and reflectance was controllably altered by up to 0.4. Refinement of fabrication techniques yielded a slow switching device, whose time-resolved reflectance data was analyzed. A wavelength dependence of the device switching speed was observed. This phenomenon was described by modelling where bandgap effects match observation. These devices may be improved by employing a 3D photonic crystal. We developed a nanoimprint lithography technique for seeding films deposited by GLAD for the fabrication of 3D square spiral photonic crystals. Parameters for patterning a precisely defined mould pattern using electron beam lithography were established. A large area diamond:1 square spiral photonic crystal was fabricated on the nanoimprinted seeds, and it exhibited a visible wavelength bandgap. / Micro-Electro-Mechanical Systems (MEMS) and Nanosystems

Electron beam lithography (EBL) and Nanoimprint Lithography (NIL) are the promising tools for today’s technology in terms of resolution capability, fidelity and cost of operation. Achieving highest possible resolution is a key concept for EBL where there is a huge request in applications of nanotechnology for sub-20 nm feature sizes. Defining features at these length scales is a challenge, and there is a large demand for resist that is not only capable of giving high resolution but also having low cost and ease of process. In this work I studied Polystyrene (PS) which is an alternative organic e-beam resist in terms of ease of process and resolution capability. I examined the process of electron-beam exposure and attempted to characterize the factors that affect the achieved resolution and sensitivity. Besides this work, I designed and fabricated a new type of mold for NIL since mold fabrication is a key factor for NIL technology. The resolution of NIL process depends on the mold features and polymer mold technology received great attention in terms of cost of fabrication and process, fidelity, and reliability. I used MD 700 Fluoropolymer as a new type of polymer mold which was believed to be a good candidate for the polymer mold of high throughput NIL.

During the last decade, surface plasmon resonance (SPR) has become widely used to characterize a biological surface and to characterize binding events in the fields of chemistry and biochemistry. Research in this field has been favoured by the tremendous growth in nanofabrication methods among which soft lithographies are alternatively emerging. The purpose of this thesis work was to develop soft UV nanoimprint lithography, an emerging flexible technology allowing patterning on large area of subwavelength photonic nanostructures. The main advantages offered by soft UV nanoimprint lithography concern the simple patterning procedure and the low cost of the experimental setup (see state-of-art presented in chapter 1). Chapters 2 and 3 present the fabrication of master stamps, the study of nanoimprinting parameters coupled with the optimization of the etching process in order to get metallic nanostructures with limited pattern defects. The physical mechanisms of the transmission phenomenon exalted by surface plasmons were studied based on arrays of imprinted gold nanoholes (chapter 4). Extraordinary light transmission has been experimentally demonstrated. The geometrical effects on the position transmission peak were systematically analyzed. Proof-of-concept measurements performed in simple fluidic device indicate a response to small changes in refractive index in the surface vicinity. Finally, chapter 5 proposes a novel design for the optical sensor which is based on "nanocavities" exhibiting coupled localized plasmons. This LSPR sensor offers an improvement of one order of magnitude of the Figure of Merit compared to classical LSPR sensors. The resonance properties of these innovative nanocavities have been studied from numerical simulations and discussed based on their geometrical dependence. Since this system has demonstrated higher sensitivity for detection of biomolecules, it is thus fully adapted to study immunochemical binding interactions.

No description available.

Although a large number of works on nanoimprint lithography (NIL) techniques have been reported, the the ability for three-dimensional (3-D) patterning using NIL has not been fully addressed in terms of the mold fabrication and imprint processes. Patterning 3-D and multilevel features are important because they eliminate multiple steps and complex interlevel alignments in the nanofabrication process. The 3-D and multilevel mold design and fabrication, and imprint processes have been studied and investigated in this research work. In the UV-NIL technique, a transparent mold with micro/nanostructure patterns on its surface is allowed to be replicated on UV curable polymer without the need of high applied pressure or temperature. UV-NIL has the potential to fabricate micro/nanostructures with high resolution, high reproducibility, low cost, high throughput and is capable of 3-D patterning. This research focuses on two aspects; the development of mold making and imprint processes. In the process of making a master mold, an EBL technique was employed for writing patterns on e-beam resists. PMMA positive resist was used for 2-D patterning and ma-N2403 negative resist from Microresist Technology was used for 3-D patterning. After being developed, the 3-D mold pattern was transferred onto quartz substrate using a single-step reactive ion etching (RIE) technique. A number of challenging issues such as surface charging, electron scattering and proximity effects surfaced during the EBL pattern writing on insulating and transparent molds. A number of new approaches have been developed for suppressing the charging effects in the 2-D and 3-D patterning. Using thin metallic coating on the quartz substrates or on top of the resist, or conductive polymer coating using PEDOT/PSS on top of the resist has demonstrated excellent results in a 2-D structure with a high aspect-ratio of 1:10 and feature sizes down to 60 nm. In 3-D patterning, two approaches have been followed; the critical energy method and/or a top coating of conductive polymer (PEDOT/PSS) layer. Isolated 3-D structures with feature sizes down to 500 nm were successfully fabricated using the first method while by using the second method, dense 3-D structures patterns with feature sizes down to 300 nm, on 400 nm pitch have been demonstrated. In UV-NIL, the surface roughness Rq(rms) should be less than 5 nm, which is important for replicating optical structures and devices. In this work, the RIE process been optimized to yield 2 nm roughness on a patterned quartz surface. This was achieved by optimizing the RIE process pressure of below 6 mTorr. The other part of this thesis is on replication or imprinting of 2-D and 3-D structures. In the process of replicating the master mold profiles, the imprint processes were carried out using a vacuum operated manual imprint tool which was attached to a Mask Aligner UV illumination system. In 2-D imprinting, resist sticking on the vertical side wall was the main issue, especially on high aspect ratio structures. Meanwhile in 3-D imprinting, the imprint results have shown good reproducibility in up to 15 imprint cycles, where the issue of Ormocomp soft/daughter mold cracking after long UV exposure had limited the repetition of the imprint cycles. In this thesis, the 2-D and 3-D resist patterning on insulating substrates using the EBL technique have been demonstrated with the assistance of a number of developed charge suppression methods. Single-step RIE pattern transfer onto quartz substrates with surface roughness below 5nm has been achieved. Replication of 3-D and multilevel structures reliably make the UV-NIL technique suitable for future applications such as surface texturing, optical devices and many other complex structures including MEMS.

Electron beam lithography (EBL) and Nanoimprint Lithography (NIL) are the promising tools for today’s technology in terms of resolution capability, fidelity and cost of operation. Achieving highest possible resolution is a key concept for EBL where there is a huge request in applications of nanotechnology for sub-20 nm feature sizes. Defining features at these length scales is a challenge, and there is a large demand for resist that is not only capable of giving high resolution but also having low cost and ease of process. In this work I studied Polystyrene (PS) which is an alternative organic e-beam resist in terms of ease of process and resolution capability. I examined the process of electron-beam exposure and attempted to characterize the factors that affect the achieved resolution and sensitivity. Besides this work, I designed and fabricated a new type of mold for NIL since mold fabrication is a key factor for NIL technology. The resolution of NIL process depends on the mold features and polymer mold technology received great attention in terms of cost of fabrication and process, fidelity, and reliability. I used MD 700 Fluoropolymer as a new type of polymer mold which was believed to be a good candidate for the polymer mold of high throughput NIL.