Functional surface micropatterns by dewetting of thin polymer films

Patterned polymer surfaces are of great importance with respect to an increasing number of technological and bio-medical applications, due to their great versatility in terms of chemical composition, properties and processing techniques. Surface micro-patterning by spontaneous dewetting of thin polymer films represents a versatile and robust process to fabricate surfaces with controlled topography and chemistry at the micro-scale. In this Thesis, we used polymer dewetting in combination with complementary approaches to engineer both surface chemistry and the ordering of the dewetting patterns. The dewetting of poly(D,L-glycolide-co-lactide) (PLGA) thin films on polystyrene (PS) was combined with the grafting of protein-repellent poly(ethylene glycol) (PEG), in order to form topographical and chemical surface micropatterns consisting in protein-adhesive PS domains surrounded by protein-repellent PEG-grafted PLGA films. The produced micropatterned surfaces were used for site-specific protein adsorption, and represent a promising platform for biological applications, such as proteomics, single-cell studies and tissue engineering. Spatially ordered surface micropatterns were obtained by combining polymer dewetting with microcontact printing and colloidal lithography, respectively. The dewetting of thin PS films was guided within specific regions of the substrate by prestamping of the silicon substrate with self-assembled monolayers of an alkylsilane by microcontact printing. Ordered micropatterns consisting in arrays of holes with tunable size were obtained by exploiting the spontaneous dewetting of poly(4-vinyl pyridine) (P4VP) thin films on PS from the holes produced by colloidal imprinting with two-dimensional colloidal crystals assembled on the polymer bilayer

Functional surface micropatterns by dewetting of thin polymer films

Patterned polymer surfaces are of great importance with respect to an increasing number of technological and bio-medical applications, due to their great versatility in terms of chemical composition, properties and processing techniques. Surface micro-patterning by spontaneous dewetting of thin polymer films represents a versatile and robust process to fabricate surfaces with controlled topography and chemistry at the micro-scale. In this Thesis, we used polymer dewetting in combination with complementary approaches to engineer both surface chemistry and the ordering of the dewetting patterns. The dewetting of poly(D,L-glycolide-co-lactide) (PLGA) thin films on polystyrene (PS) was combined with the grafting of protein-repellent poly(ethylene glycol) (PEG), in order to form topographical and chemical surface micropatterns consisting in protein-adhesive PS domains surrounded by protein-repellent PEG-grafted PLGA films. The produced micropatterned surfaces were used for site-specific protein adsorption, and represent a promising platform for biological applications, such as proteomics, single-cell studies and tissue engineering. Spatially ordered surface micropatterns were obtained by combining polymer dewetting with microcontact printing and colloidal lithography, respectively. The dewetting of thin PS films was guided within specific regions of the substrate by prestamping of the silicon substrate with self-assembled monolayers of an alkylsilane by microcontact printing. Ordered micropatterns consisting in arrays of holes with tunable size were obtained by exploiting the spontaneous dewetting of poly(4-vinyl pyridine) (P4VP) thin films on PS from the holes produced by colloidal imprinting with two-dimensional colloidal crystals assembled on the polymer bilayer

Vakuum-UV-Spektroskopie an synthetischem Quarzglas unter UV-Pulslaserbestrahlung

Die optische Degradation von synthetischem Quarzglas unter UV-Pulslaserbestrahlung kann als photolytisches Aufbrechen von Bindungen und anschließende Relaxation sowohl durch die Neuformierung dieser Bindungen als auch durch die Entstehung von neuen Bindungen interpretiert werden. Damit verbunden sind strukturelle Veränderungen im Glasnetzwerk sowie eine Änderung des Ordnungszustandes im amorphen Festkörper. Diese Änderung sollte sich auf die Form und die Lage der Absorptionskante auswirken, deren Verlauf durch die Urbach-Energie und den optischen Bandabstand charakterisiert werden kann. Aus diesem Grund sind die Urbach-Energie und der optische Bandabstand geeignete Parameter zur Charakterisierung der laserinduzierten Strukturänderungen im Material. In der vorliegenden Arbeit wird die Änderung von Urbach-Energie und optischem Bandabstand synthetischer Quarzgläser unter ArF-Pulslaserbestrahlung (193 nm) untersucht. Die dazu entwickelten, aufeinander aufbauenden Verfahren zur quantitativen Bestimmung der beiden Größen aus den Absorptionsspektren wird beschrieben. Der Verlauf von Urbach-Energie und optischem Bandabstand während der Laserbestrahlung wird durch ein einfaches kinetisches Modell dargestellt und die daraus resultierenden Modellparameter werden verglichen und diskutiert. Daran anschließend werden mögliche physikalische Ursachen für das spezifische Verhalten der beiden Größen unter ArF-Pulslaserbestrahlung diskutiert. Zusätzlich wird die laserinduzierte Änderung der Absorption im niederenergetischen Bereich der Spektren (hv < 7 eV) während der ArF-Pulslaserbestrahlung untersucht. Dazu wird der Einfluß des niederenergetischen Urbach-Flankenausläufers auf diesen Bereich der Spektren evaluiert. Nach der Separation des Urbach-Flankenausläufers wird die Absorption im niederenergetischen Bereich der Spektren anhand von Literaturbefunden zur lokalen Defektabsorption diskutiert

High performance silica glass produced by flame aerosol method for photonic components

Orientador: Carlos Kenichi SuzukiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecanicaResumo: Neste trabalho estudou-se o efeito da variação dos parâmetros do processo VAD (Vaporphase Axial Deposition) sobre as propriedades estruturais e ópticas da sílica vítrea visando o desenvolvimento de um material de alto desempenho óptico empregado no sistema óptico de equipamentos litográficos. As propriedades estruturais das preformas foram caracterizadas por microscopia eletrônica de varredura (MEV), espalhamento de raios-X a baixo ângulo (SAXS) e espectroscopia de absorção de estrutura fina de raios-X (XAFS). Absorção de raios-X (ARX) e tratamento de imagem digital foram utilizados para a obtenção da distribuição radial da densidade e da densidade média da sílica porosa, respectivamente. As propriedades ópticas foram determinadas por interferometria, espectroscopia óptica, espectrometria de polarização, espectroscopia Raman, espectroscopia no infravermelho e espectrofotometria de absorção óptica. Como principal resultado, obteve-se sílica vítrea com homogeneidade radial da estrutura, ?n = 3 ppm, birrefringência = 2 nm/cm e transmitância de 87 % em ? = 400 nm quando consolidada em atmosfera de He podendo superar 90 % quando consolidadas em vácuo. Este desempenho óptico foi obtido em até 95 % do diâmetro da preforma sem a necessidade de etapas adicionais, como o recozimento e a extração da região do diâmetro externo da preforma (geralmente a parte heterogênea) através de corte, reduzindo significativamente o tempo e custo de fabricação da sílica.Abstract: This research reports the study of the effect of processing parameters of VAD (Vapor-phase Axial Deposition) method on structural and optical properties of silica glass aiming the development of an optically homogeneous material for use on lithographic equipments. The structural properties were characterized by the scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), and X-ray absorption fine structure (XAFS). X-ray absorption (XRA) and digital image processing were used to obtain the density radial distribution and average density of silica soot, respectively. The optical properties were determined by interferometry, optical spectroscopy, polarization spectrometry, Raman spectroscopy, infrared spectroscopy, and optical absorption spectrophotometry. As a main result, silica glass was produced with structural radial homogeneity, ?n = 3 ppm, birefringence = 2 nm/cm, and transmittance of 87 % at ? = 400 nm when it was consolidated with He atmosphere and higher than 90 % in vacuum. This optical performance was obtained in 95 % of preform diameter without additional steps, such as annealing and cutting of preform outer diameter region (usually the heterogeneous part) which significantly reduces the time and cost of silica fabrication.DoutoradoMateriais e Processos de FabricaçãoDoutor em Engenharia Mecânic

Setup of an optical time-domain matter wave interferometer for heavy particles

In dieser Arbeit werden Planung und Aufbau eines neuen Materiewellen Talbot-Lau Interferometers dokumentiert. Das Experiment soll in Zukunft den quantenmechanischen Wellencharakter von zunehmend schwereren Teilchen nachweisen, wobei die Massengrenze für den Aufbau bei ca. 25.000 amu liegt. Dies übersteigt den derzeitigen Massenrekord für Materiewellen Interferometrie um mehr als das Dreifache. Um dieser Herausforderung gerecht zu werden ist das Interferometer erstmals mit gepulsten absorptiven Ionisationslasergittern ausgerüstet, welch gegenüber materiellen Gittern den Vorteil nahezu perfekter Periodizität aufweisen bei einer bisher bei Molekülinterferometern unerreicht kleinen Gitterkonstante von 78,6 nm. Außerdem treten bei Lasergittern keine dispersiven Wechselwirkungen zwischen Teilchen und Gittern auf, von denen bekannt ist, daß sie den maximal möglichen Interferenzkontrast in Talbot-Lau Interferometern für große Massen drastisch reduzieren. Das neue Interferometer verspricht somit hohen Interferenzkontrast auch für schwere und langsame Teilchen, wobei Pulsen des Experiments breite Geschwindigkeitsverteilungen im Teilchenstrahl zuläßt und damit hohe Zählraten für große Teilchenmassen verspricht. Es ist hervorzuheben, daß die Technik, welche für die Lasergitter entwickelt wurde, in Zukunft den Aufbau von Interferometern ermöglicht mit Massengrenzen sogar jenseits von 10^6 amu.In this thesis the setup of an optical time-domain ionizing matter wave Talbot-Lau interferometer (OTIMA-TLI) is discussed. The experiment aims at demonstrating the quantum wave nature of increasingly heavy particles. The mass limit of the current version lies around 25.000 amu which is more than three times higher than the present-day mass record for matter wave interferometry. In order to be especially suited for this purpose the OTIMA-TLI is equipped, for the first time, with pulsed ionizing absorptive laser gratings with a grating period of 78,6 nm. Such gratings are perfectly periodic and come without dispersive grating-particle interactions thus promising high contrast interference even for massive and slow particles. Working with pulsed gratings additionally allows for greater velocity spread within the particle beam which promises higher count rates at high particle masses. The techniques and methods we have developed will in future enable the implementation of matter wave interferometers with a mass limit exceeding 10^6 amu. The experiment is currently in the build-up phase and this work documents the design and experimental realization both in theory and in practice

Novel resists for next generation lithography

With progress in the semiconductor industry, transistor density on a single computer chip has increased dramatically. This has resulted in a continuous shrinkage of the minimum feature size printed through microlithography technology. Resist, as the pattern recording medium of such printing, has been extensively studied to achieve higher resolution, higher sensitivity and lower line edge roughness. For decades this has been realized through chemical amplification. With the feature size continuously shrinking and the energy of exposure source therefore exceeding the resist ionization threshold, the performance of conventional chemically amplified resists is approaching the limits. Novel high-performance chemically amplified resists or non-chemically amplified resists are urgently needed to meet the requirement of next generation lithography. In this work a negative tone chemically amplified resist system based on a novel method to control the catalytic chain reaction is presented. The method to control the catalytic chain reaction is demonstrated using two model polymer resists. This method is then applied to a fullerene-based molecular resist system and a combination of good industrial compatibility, high resolution and good sensitivity has been achieved in this resist. Through a chromatographic separation, another chemically amplified molecular resist was also developed with further improved performance. An alternative route to sensitivity improvement other than chemical amplification is then introduced and a family of fullerene-based metal containing materials is presented. Lithographic performance is compared between the fullerene-metal resists and their control materials without metal. Using an aberration corrected scanning transmission electron microscope, the distribution of metal in the resist film and its behavior during the lithography process is evaluated and discussed

Photolithographic and replication techniques for nanofabrication and photonics

In the pursuit of economical and rapid fabrication solutions on the micro and nano scale, polymer replication has proven itself to be a formidable technique, which despite zealous development by the research community, remains full of promise. This thesis explores the potential of elastomers in what is a distinctly multidisciplinary field. The focus is on developing innovative fabrication solutions for planar photonic devices and for nanoscale devices in general. Innovations are derived from treatments of master structures, imprintable substrates and device applications. Major contributions made by this work include fully replicated planar integrated optical devices, nanoscale applications for photolithographic standing wave corrugations (SWC), and a biologically templated, optical fiber based, surface-enhanced Raman scattering (SERS) sensor. The planar devices take the form of dielectric rib waveguides which for the first time, have been integrated with long-period gratings by replication. The heretofore unemployed SWC is used to demonstrate two innovations. The first is a novel demonstration of elastomeric sidewall photolithographic mask, which exploits the capacity of elastomers to cast undercut structures. The second demonstrates that the corrugations themselves in the absence of elastomers, can be employed as shadow masks in a directional flux to produce vertical stacks of straight lines and circles of nanowires and nanoribbons. The thesis then closes by conceptually combining the preceding demonstrations of waveguides and nanostructures. An optical fiber endface is em ployed for the first time as a substrate for patterning by replication, wherein the pattern is a nanostructure derived from a biological template. This replicated nanostructure is used to impart a SERS capability to the optical fiber, demonstrating an ultra-sensitive, integrated photonic device realized at great economy of both time and money, with very real potential for mass fabrication

Laser assisted nano-optics processing in optical data storage

Ph.DDOCTOR OF PHILOSOPH

Resolution Improvement and Pattern Generator Development for theMaskless Micro-Ion-Beam Reduction Lithography System

The shrinking of IC devices has followed the Moore's Law for over three decades, which states that the density of transistors on integrated circuits will double about every two years. This great achievement is obtained via continuous advance in lithography technology. With the adoption of complicated resolution enhancement technologies, such as the phase shifting mask (PSM), the optical proximity correction (OPC), optical lithography with wavelength of 193 nm has enabled 45 nm printing by immersion method. However, this achievement comes together with the skyrocketing cost of masks, which makes the production of low volume application-specific IC (ASIC) impractical. In order to provide an economical lithography approach for low to medium volume advanced IC fabrication, a maskless ion beam lithography method, called Maskless Micro-ion-beam Reduction Lithography (MMRL), has been developed in the Lawrence Berkeley National Laboratory. The development of the prototype MMRL system has been described by Dr. Vinh Van Ngo in his Ph.D. thesis. But the resolution realized on the prototype MMRL system was far from the design expectation. In order to improve the resolution of the MMRL system, the ion optical system has been investigated. By integrating a field-free limiting aperture into the optical column, reducing the electromagnetic interference and cleaning the RF plasma, the resolution has been improved to around 50 nm. Computational analysis indicates that the MMRL system can be operated with an exposure field size of 0.25 mm and a beam half angle of 1.0 mrad on the wafer plane. Ion-ion interactions have been studied with a two-particle physics model. The results are in excellent agreement with those published by the other research groups. The charge-interaction analysis of MMRL shows that the ion-ion interactions must be reduced in order to obtain a throughput higher than 10 wafers per hour on 300-mm wafers. In addition, two different maskless lithography strategies have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3{delta} CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator