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3D transcription pf 2D binary chemical nanopatterns by block-copolymer dewettingBaralia, Gabriel 14 December 2006 (has links)
This work focuses on binary chemical nano-patterning and on aspects related to the self-organization and stability during and after dewetting of thin block-copolymer films on chemically nano-patterned substrates.
Regarding surface functionalization with thiols, the exchange of thiols in both liquid and gas phase was first investigated. The aim was to control thiols-assembly on gold and thus to fabricate unscrambled binary chemical nano-patterns. The systems gold-thiols are considered as alternatives to silicon oxide-silanes systems in the chemical nano-patterning processes because of fabrication simplicity reasons.
The strategy developed to avoid thiol exchange was used to fabricate unscrambled binary chemical nano-patterns combining a top-down approach, Electron Beam Lithography (EBL), and a bottom-up approach based on the self-assembly of thiols on gold.
Than, using the chemically nano-patterned surfaces previously developed, the organization processes of thin block-copolymer films were studied. Thin symmetric and asymmetric diblock copolymer films were deposited on engineered substrates consisting of alternating less and more wettable stripes. By locally tuning the chemical properties of the substrate, the interaction potential between the polymer and the substrate can be manipulated. It was thus possible to force a liquid film to dewet or to self-organize in a variety of configurations through phase preparation, specific interactions, confinement.
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Self-ordering of spherical nanoparticles in a block copolymer systemPapalia, John M. January 2007 (has links)
Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Mary E. Galvin-Donoghue, Dept. of Materials Science & Engineering. Includes bibliographical references.
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Solvent annealing and thickness control for the orientation of silicon-containing block copolymers for nanolithographic applicationsSantos, Logan Joseph 18 July 2012 (has links)
Block copolymers are an ideal solution for a wide variety of nanolithographic opportunities due to their tendency to self-assemble on nanoscopic length scales. High etch selectivity and thin-film orientation are crucial to the success of this technology. Most conventional block copolymers have poor etch selectivity; however, incorporating silicon into one block produces the desired etch selectivity. A positive side effect of the silicon addition is that the χ value (a block-to-block interaction parameter) of the block copolymer increases. This decreases the critical dimension of potential features. Unfortunately, one negative side effect is the increase in the surface energy difference between the blocks. Incorporating silicon decreases the surface energy of that block. Typically, annealing is used to induce the chain mobility that is required for the block copolymer to reach its minimum thermodynamic energy state. Thermal annealing is the easiest annealing technique; however, if the glass transition temperature (Tg) of one block is above the thermal decomposition temperature of the other block, the latter will degrade before the former can reorient. In addition, annealing silicon-containing block copolymers usually results in a wetting layer and parallel orientation since the lower surface energy block favors the air interface, minimizing the free energy. Solvent annealing replaces the air interface with a solvent, thereby changing the surface energy. The solvent plasticizes the block copolymer, effectively decreasing the Tgs of both blocks. Another benefit is the ability to reversibly alter the orientation by changing the solvent or solvent concentration. The challenge with solvent annealing is that it depends on a number of parameters including: solvent selection, annealing time, and vapor concentration, which generate a very large variable space that must be searched to find optimum screening conditions. / text
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Advanced materials for block copolymer lithographyBates, Christopher Martin 11 July 2014 (has links)
The multi-billion dollar per year lithography industry relies on the fusion of chemistry, materials science, and engineering to produce technological innovations that enable continual improvements in the speed and storage density of microelectronic devices. A critical prerequisite to improving the computers of today relies on the ability to economically and controllably form thin film structures with dimensions on the order of tens of nanometers. One class of materials that potentially meets these requirements is block copolymers since they can self-assemble into structures with characteristic dimensions circa three to hundreds of nanometers. The different aspects of the block copolymer lithographic process are the subject of this dissertation. A variety of interrelated material requirements virtually necessitate the synthesis of block copolymers specifically designed for lithographic applications. Key properties for the ideal block copolymer include etch resistance to facilitate thin film processing, a large interaction parameter to enable the formation of high resolution structures, and thin film orientation control. The unifying theme for the materials synthesized herein is the presence of silicon in one block, which imparts oxygen etch resistance to just that domain. A collection of silicon-containing block copolymers was synthesized and characterized, many of which readily form features on approximately the length scale required for next-generation microelectronic devices. The most important thin film processing step biases the orientation of block copolymer domains perpendicular to the substrate by control of interfacial interactions. Both solvent and thermal annealing techniques were extensively studied to achieve orientation control. Ultimately, a dual top and bottom surface functionalization strategy was developed that utilizes a new class of "top coats" and cross-linkable substrate surface treatments. Perpendicular block copolymer features can now be produced quickly with a process amenable to existing manufacturing technology, which was previously impossible. The development of etching recipes and pattern transfer processes confirmed the through-film nature of the features and the efficacy of both the block copolymer design and the top coat process. / text
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Self-assembly of block coplymer thin films in compressible fluidsLi, Yuan, 1968- 28 August 2008 (has links)
Not available / text
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Advanced organic materials for lithographic applicationsStrahan, Jeffrey Ryan 20 October 2011 (has links)
The microelectronics industry is driven by the need to produce smaller
transistors at lower costs, and this requires an ever-changing approach to the
chemistry involved in their fabrication. While photolithography has been able to
keep pace with Moore’s law over the past four decades, alternative patterning
technologies are now receiving increased attention to keep up with market
demand.
The first project describes work towards increasing the sensitivity of
electron-beam resists by incorporating electron-withdrawing groups into the alpha
position of methacrylates. After monomer design and synthesis, several polymers
were synthesized that investigated the role of fluorine in the resists performance.
G-values, electron-beam contrast curves, and EUV imaging showed that these
fluorinated polymethacrylates outperformed current industrial resists.
The next project deals with the design, synthesis, and evaluation of a resist
that seeks to decouple chemical amplification from acid diffusion. While work
was shown that a system comprised of a photo-labile polyphthalaldehyde and
x
novolak could achieve this process, the high dose required to image was
problematic. An aliphatic dialdehyde was envisioned to account for these issues,
but its synthesis was never achieved. A polyethylene glycol aldehyde was
synthesized and polymerized, but its material properties did not perform the
intended function. Ultimately, the stability of aliphatic aldehydes proved to be
too unstable for this project to continue.
While the synthesis was troublesome, a fundamental study of ceiling
temperatures was undertaken. Numerical and analytical solutions were developed
that describe the exact nature of the equilibrium constant on a living polymer
system. These results were verified by a VT-NMR experiment, which accurately
predicted the ceiling temperature of polythalaldehyde with a Van’t Hoff plot.
Lastly, the self-assembly of block copolymers was investigated as a means
to produce high resolution, high density nano-imprint lithography templates for
bit patterned media. The first set of experiments involved synthesizing polymeric
cross-linked surface treatments from substituted styrenes. The aryl substituent
was shown to largely effect the surface energy, and after anionically synthesizing
PS-b-PMMA, these materials were shown to effect block copolymer orientation.
To produce a 3-D pattern of the self-assembled features, silicon was incorporated
into one block to provide adequate etch resistance. Several monomers were
investigated, and two, an isoprene and methacrylate analog, were successfully
incorporated into two block copolymers. The silicon containing methacrylate
derivative polymer was shown to successfully self-assemble in thin films under
solvent annealing conditions. / text
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Patterning of Nanostructures by Block Copolymer Self-AssemblyZhang, Xiaojiang Unknown Date
No description available.
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CONTROL OF KEY POLYMER PROPERTIES VIA REVERSIBLE ADDITION-FRAGMENTATION CHAIN TRANSFER IN EMULSION POLYMERIZATIONAltarawneh, Ibrahem January 2009 (has links)
Doctor of Philosophy (PhD), Engineerig / Free radical emulsion polymerization (FRP) is widely adopted in industry due to its applicability to a wide range of monomers. Despite its many benefits and wide spread use, the fast chain growth and the presence of rapid irreversible termination impose limitations with respect to the degree of control in FRP. Furthermore, producing block copolymers and polymers with complex structures via FRP is not feasible. Closer control of macromolecular chain structure and molar mass, using novel polymerization techniques, is required to synthesize and optimize many new polymer products. Reversible addition fragmentation chain transfer (RAFT)-mediated polymerization is a novel controlled living free radical technique used to impart living characters in free radical polymerization. In combination with emulsion polymerization, the process is industrially promising and attractive for the production of tailored polymeric products. It allows for the production of particles with specially-tailored properties, including size, composition, morphology, and molecular weights. The mechanism of RAFT process and the effect of participating groups were discussed with reviews on the previous work on rate retardation. A mathematical model accounting for the effect of concentrations of propagating, intermediate, dormant and dead chains was developed based on their reaction pathways. The model was combined with a chain-length dependent termination model in order to account for the decreased termination rate. The model was validated against experimental data for solution and bulk polymerizations of styrene. The role of the intermediate radical and the effect of RAFT agent on the chain length dependent termination rate were addressed theoretically. The developed kinetic model was used with validated kinetic parameters to assess the observed retardation in solution polymerization of styrene with high active RAFT agent (cumyl dithiobenzoate). The fragmentation rate coefficient was used as a model parameter, and a value equal to 6×104 s-1 was found to provide a good agreement with the experimental data. The model predictions indicated that the observed retardation could be attributed to the cross termination of the intermediate radical and, to some extent, to the RAFT effect on increasing the average termination rate coefficient. The model predictions showed that to preserve the living nature of RAFT polymerization, a low initiator concentration is recommended. In line with the experimental data, model simulations revealed that the intermediate radical prefers fragmentation in the direction of the reactant. The application of RAFT process has also been extended to emulsion polymerization of styrene. A comprehensive dynamic model for batch and semi-batch emulsion polymerizations with a reversible addition-fragmentation chain transfer process was developed. To account for the integration of the RAFT process, new modifications were added to the kinetics of zero-one emulsion polymerization. The developed model was designed to predict key polymer properties such as: average particle size, conversion, particle size distribution (PSD), and molecular weight distribution (MWD) and its averages. The model was checked for emulsion polymerization processes of styrene with O-ethylxanthyl ethyl propionate as a RAFT based transfer agent. By using the model to investigate the effect of RAFT agent on the polymerization attributes, it was found that the rate of polymerization and the average size of the latex particles decreased with increasing amount of RAFT agent. It was also found that the molecular weight distribution could be controlled, as it is strongly influenced by the presence of the RAFT based transfer agent. The effects of RAFT agent, surfactant (SDS), initiator (KPS) and temperature were further investigated under semi-batch conditions. Monomer conversion, MWD and PSD were found to be strongly affected by monomer feed rate. With semi-batch mode, Mn and <r> increased with increasing monomer flow rate. Initiator concentration had a significant effect on PSD. The results suggest that living polymerization can be approached by operating under semi-batch conditions where a linear growth of polymer molecular weight with conversion was obtained. The lack of online instrumentation was the main reason for developing our calorimetry-based soft-sensor. The rate of polymerization, which is proportional to the heat of reaction, was estimated and integrated to obtain the overall monomer conversion. The calorimetric model developed was found to be capable of estimating polymer molecular weight via simultaneous estimation of monomer and RAFT agent concentrations. The model was validated with batch and semi-batch emulsion polymerization of styrene with and without RAFT agent. The results show good agreement between measured conversion profiles by calorimetry with those measured by the gravimetric technique. Additionally, the number average molecular weight results measured by SEC (GPC) with double detections compare well with those calculated by the calorimetric model. Application of the offline dynamic optimisation to the emulsion polymerization process of styrene was investigated for the PSD, MWD and monomer conversion. The optimal profiles obtained were then validated experimentally and a good agreement was obtained. The gained knowledge has been further applied to produce polymeric particles containing block copolymers. First, methyl acrylate, butyl acrylate and styrene were polymerized separately to produce the first block. Subsequently, the produced homopolymer attached with xanthate was chain-extended with another monomer to produce block copolymer under batch conditions. Due to the formation of new particles during the second stage batch polymerization, homopolymer was formed and the block copolymer produced was not of high purity. The process was further optimized by operating under semi-batch conditions. The choice of block sequence was found to be important in reducing the influence of terminated chains on the distributions of polymer obtained. It has been found that polymerizing styrene first followed by the high active acrylate monomers resulted in purer block copolymer with low polydispersity confirmed by GPC and H-NMR analysis.
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Nanoscale hierarchical phase behavior of liquid crystalline block copolymers /Tenneti, Kishore Kumar. Li, Christopher Yuren. January 2008 (has links)
Thesis (Ph.D.)--Drexel University, 2008. / Includes abstract and vita. Includes bibliographical references (leaves 222-234).
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Design and optimization of polymer nanostructures for signal amplificationNassif, Rachel D. January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Chemistry. Title from title page of PDF (viewed 2008/12/07). Includes bibliographical references.
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