Nanotechnology has a steadily increasing impact on worldwide research and business activities. This work explores advanced micro/nano patterning approaches for molecular manipulation. The objectives are to (1) build a proper bridge from a few microns to the 100-10 nm range and below as well as to (2) combine “top-down” precise design with the “bottom-up” size scale to create designed surfaces, areas and volumes that can interact with molecules in a designed way. Three studies were designed and studied accordingly. The first investigation demonstrates that “top-down” Inclined Nanoimprinting Lithography (INIL) is able to produce three-dimensional (3-D) nanopatterns of varying heights in a single step. INIL reduces pattern's feature size from microns to nanometers. The degree of resulting nanopattern's asymmetry can be controlled by the magnitude of the inclination angle. Various 3-D nanostructures are successfully demonstrated including nanolines, nanocircles and nanosquares. The underlying INIL mechanism is investigated, which is primarily due to the induced shear force when the inclination angle is not zero. This leads to the anisotropic dewetting of polymer fluid and consequently asymmetric 3D nanopatterns of varying heights. INIL removes the need of preparation of expensive 3D nanotemplates or multiple template-to-substrate alignments. In addition, such 3-D structures are successfully transferred to silicon, silicone rubber and metal gold. INIL enables 3D nano-scale devices including angle-resolved photonic and plasmonic crystals. The second investigation demonstrates the success of “bottom-up” molecular imprinting of X-ray contrast agent iodixanol in polymer matrix. The synthetic tailor-made molecularly imprinted polymers (MIPs) are poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) which possess specific binding sites induced by the template molecules of X-ray contrast agent iodixanol. It leads the feature size reduction from macromolecules to molecular scale. The properly imprinted binding sites also leads MIPs to have improved absorption capacity and efficiency for X-ray contrast agent iodixanol relative to non-imprinted polymers. The best binding capacity achieved from the optimized MIPs was 284 mg/g in aqueous solution, 8.8 times higher than that of the non-imprinted polymers. The best binding capacity obtained in sheep plasma was 232 mg/g, 4.5 times higher than the non-imprinted polymers. The factors that may affect the binding performance of MIPs in aqueous media are studied. The optimized MIPs are encouraging for biomedical implementations including dialysis and nanosensors. The third investigation of nanolithography-based molecular manipulation (NMM) explores a hybrid approach by combining “top-down” electron-beam lithography (EBL) with “bottom-up” surface initiated polymerization (SIP). It reduces the nanopattern's feature size to sub-10 nm and simultaneously tunes its surface chemistry through functional polymer brushes. The process has reduced process complexity and cost. The demonstrated prototype molecular manipulation templates have 3D surface nanostructures with sub-10 nm feature size and anisotropic surface functionalities. They mimic biocatalyst enzymes to “bottom-up” assemble nanoparticle targets at specific locations producing 3D nanostructures in a designated way. Various 3D synthetic nanostructures have been demonstrated including polystyrene “nanomushrooms” “nanospikes”, “nanofibers” and polystyrene-iron oxide “nanoflowers”. Potential applications of these synthetic 3D nanostructures can be improved therapeutic agents. This hybrid strategy realizes the integration of “top-down” design with “bottom-up” molecular scale to create designed nanopatterned surfaces that can interact with molecules in a designated way.

<p>Over the last decades, integrated circuits have changed our everyday lives in a number of ways. Many common devices today taken for granted would not have been possible without this industrial revolution.</p><p>Central to the manufacturing of integrated circuits is the photomask used to expose the wafers. Additionally, such photomasks are also used for manufacturing of flat screen displays. Microlithography, the manufacturing technique of such photomasks, requires complex electronics equipment that excels in both speed and fidelity. Manufacture of such equipment requires competence in virtually all engineering disciplines, where the conversion of geometry into pixels is but one of these. Nevertheless, this single step in the photomask drawing process has a major impact on the throughput and quality of a photomask writer.</p><p>Current high-end semiconductor writers from Micronic use a cluster of Field-Programmable Gate Array circuits (FPGA). FPGAs have for many years been able to replace Application Specific Integrated Circuits due to their flexibility and low initial development cost. For parallel computation, an FPGA can achieve throughput not possible with microprocessors alone. Nevertheless, high-performance FPGAs are expensive devices, and upgrading from one generation to the next often requires a major redesign.</p><p>During the last decade, the computer games industry has taken the lead in parallel computation with graphics card for 3D gaming. While essentially being designed to render 3D polygons and lacking the flexibility of an FPGA, graphics cards have nevertheless started to rival FPGAs as the main workhorse of many parallel computing applications.</p><p>This thesis covers an investigation on utilizing graphics cards for the task of rendering geometry into photomask patterns. It describes different strategies that were tried and the throughput and fidelity achieved with them, along with the problems encountered. It also describes the development of a suitable evaluation framework that was critical to the process.</p>

Two technologies, immersion and imprint lithography, represent important stepping stones for the development of the next generation of lithography tools. However, although the two approaches offer important advantages, both pose many significant technological challenges that must be overcome before they can be successfully implemented. For imprint lithography, special care must be taken when choosing an etch barrier because studies have indicated that some physical material properties may be size dependent. Additionally, regarding immersion lithography, proper image focus requires that the optical path length between the lens and substrate be maintained during the entire writing process. The work described in this document was undertaken to address the two challenges described above. A new mathematical model was developed and used in conjunction with AFM nano-indentation techniques to measure the elastic modulus of adhesive, thin polymer films as a function of the film thickness. It was found that the elastic modulus of the polymer tested did not change appreciably from the value determined using bulk measurement techniques in the thickness range probed. Additionally, a method for monitoring and controlling the optical path length within the gap of a nearly index-matching cavity based on coherent broadband interference was developed. In this method, the spectrum reflected for a cavity illuminated with a modelocked Ti:Sapphire laser was collected and analyzed using Fourier techniques. It was found that this method could determine the optical path length of the cavity, quickly and accurately enough to control a servo-based feedback system to correct deviations in the optical path length in real time when coupled with special computation techniques that minimized unnecessary operations. / text

This work presents the novel applications of heated AFM tip in nanolithography. Different strategies were investigated for patterning materials using heated AFM tip. New materials were developed for these new nanolithography methods. Simulation and modeling work was done to further understand the heat transfer and chemical reactions involved in the thermal writing process. The selective thermal decomposition of polymer was the first thermal patterning method we¡¯ve investigated. A couple of different sacrificial polymers were used as the writing materials. Among these materials, the cross-linked amorphous polycarbonate (CPC-IV) was the best material for this application. The effect of cross-linking density on the performance of the material was investigated. A novel 3D thermal writing technology was developed by using cross-linked polymer as the writing material. A combined method utilizing the heated cantilever probe to pattern a polymer masking layer that can serve as a template for area selective atomic layer deposition techniques was developed. Another thermal probe nanolithography method, thermal probe top surface imaging, was also developed. In this method, the heated AFM tip was used to generate functional groups on the polymer surface, and ALD was used to selectively deposit TiO2 on the surface where contains those functional groups. A new poly (hydroxyl styrene) based copolymer was developed for this method. We also investigated self assembly monolayers (SAMs) as the thermal writing material. Two different SAMs were investigated. One the APTES and the other one is THP-MPTES. We demonstrated that the APTES can be patterned using thermal AFM probe, and other materials can be selectively deposited on the patterned APTES SAMs. Thermal AFM probe was used to selectively generate thiol groups from THP-MPTES SAMs, and then use these thiol groups to guide the deposition AuNPs. Some simulation and modeling works were also done to further understand these processes. FemLab was used to analyze the heat transfer in the thermal cantilever and between the heated tip and substrate. Based on kinetics of polymer thermal decomposition, we built a simple model for the selective thermal decomposition nanolithography. The experimental results can be very well fitted by this model.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

This dissertation aims to advance the current state of use of silicon atomic force microscope (AFM) cantilevers with integrated heaters. To this end, the research consists of two primary thrusts - demonstrating new applications for the cantilevers, and advancing the current state of understanding of their thermal and mechanical behavior to enable further applications. Among new applications, two are described. In the first application, the cantilevers are used for nanoscale material deposition, using heat to modulate the delivery of material from the nanoscale tip. In the second application, the cantilever performs thermal analysis with nanoscale spatial resolution, enabling thermal characterization of near surface and composite interphase regions that cannot be measured with bulk analysis techniques. The second thrust of the research seeks to address fundamental questions concerning the precision use of heated cantilevers. Efforts to this end include characterizing the mechanical, electrical, and thermal behavior of the cantilevers, and optimizing calibration methodology. A technique is developed for calibrating the cantilever spring constant while operating at elevated temperature. Finally, an analytical model is developed for the heat flow in the cantilever tip and relevant dimensionless numbers that govern the relative importance of the various components of the thermal environment are identified. The dimensionless numbers permit exploration of the sensitivity of the tip-substrate interface temperature to the environmental conditions.

The microelectronics industry has made remarkable progress with the development of integrated circuit (IC) technology which depends on the advance of micro-fabrication and integration techniques. On one hand, next-generation lithography (NGL) technologies which utilize extreme ultraviolet (EUV) and the state-of-art 193 nm immmersion and double patterning lithography have emerged as the promising candidates to meet the resolution requirements of the microelectronic industry roadmap. On the other hand, the development and advanced characterization of novel resist materials with the required critical imaging properties, such as high resolution, high sensitivity, and low line edge roughness (LER), is also indispensable. In conventional multi-component chemically amplified resist (CAR) system, the inherent incompatibility between small molecule photoacid generator (PAG) and the bulky polymer resin can lead to PAG phase separation, PAG aggregation, non-uniform PAG and acid distribution, as well as uncontrolled acid migration during the post-exposure baking (PEB) processes in the resist film. These problems ultimately create the tri-lateral tradeoff between achieving the desired lithography characteristics. Novel resist materials which can relief this constraint are essential and have become one of the most challenging issues for the implementation NGL technologies. This thesis work focuses on the development and characterization of novel resist materials for NGL technologies. In the first part of the thesis work, advanced characterization techniques for studying resist fundamental properties and lithographic performance are developed and demonstrated. These techniques provide efficient and precise evaluations of PAG acid generation, acid diffusivity, and intrinsic resolution and LER of resist materials. The applicability of these techniques to the study of resist structure-function relationships are also evaluated and discussed. In the second part of the thesis work, the advanced characterization and development of a novel resist system, the polymer-bound-PAG resists, are reported. The advantages of direct incorporation of PAG functionality into the resist polymer main chain are investigated and illustrated through both experimental and modeling studies. The structure-function relationships between the fundamental properties of polymer-bound-PAG resists and their lithographic performance are also investigated. Recommendations on substantial future works for characterizing and improving resist lithographic performance are discussed at the end of this thesis work.

The objective of this research is to investigate the use of laser direct writing to micro-pattern low loss passive optical channel waveguide devices using a new hybrid organic/inorganic polymer. Review of literature shows previous methods of optical waveguide device patterning as well as application of other non-polymer materials. System setup and design of the waveguide components are discussed. Results show that laser direct writing of the hybrid polymer produce single mode interconnects with a loss of less 1dB/cm.

The important roles of fluid dynamics in immersion lithography (IL) and step-and-flash imprint lithography (S FIL) are analyzed experimentally and theoretically. In IL there are many challenges with managing a fluid droplet between the lens and the wafer, including preventing separation of the fluid droplet from the lens and deposition of small droplets behind the lens. Fluid management is also critical in S FIL because the imprint fluid creates capillary and lubrication forces, both of which are primarily responsible for the dynamics of the template and fluid motion. The fluid flow and shape of the wafer determine how uniform the gap height between the wafer and the template is, and they affect the resistance during the alignment phase. IL was investigated as a methodology to improve laser lithography for making photomasks. The fluid flow in IL was investigated by building a test apparatus to simulate the motion of the fluid droplet during microlithographic production, and using this apparatus to conduct experiments on various immersion fluids and wafer topcoats to determine what instabilities would occur. A theoretical model was used to predict the fluid separation instabilities. Finite element simulations were also used to model the fluid droplet, and these simulations accurately predict the fluid instabilities and quantitatively agreed with the model and experiments. It is shown that the process is viable: capillary forces are sufficient to keep the fluid droplet stable, heating effects due to the laser are negligible, and other concerns such as evaporation and dissolution are manageable. Euler beam theory and the lubrication equation were used to model the bending of an S FIL template and the flow of the fluid between the template and a non-flat wafer. The template filling time, conformance of the template to the wafer, and the alignment phase are investigated with an analytical model and finite element simulations. Analysis and simulations show that uniformity of the residual film thickness and ease of proper alignment depend greatly on the planarity of the wafer, the properties of the template, and the surface tension of the fluid. / text

This research lays the foundation of a highly simplified maskless micro-fabrication technique which involves incorporation of laser direct writing technique combined with fountain pen based micro-patterning method to fabricate polymer-based Mach-Zehnder interferometer sensor arrays' prototype for chemical/biological sensing applications. The research provides methodology that focuses on maskless technology, allowing the definition and modification of geometric patterns through the programming of computer software, in contrast to the conventional mask-based photolithographic approach, in which a photomask must be produced before the device is fabricated. The finished waveguide sensors are evaluated on the basis of their performance as general interferometers. The waveguide developed using the fountain pen-based micro-patterning system is compared with the waveguide developed using the current technique of spin coating method for patterning of upper cladding of the waveguide. The resulting output power profile of the waveguides is generated to confirm their functionality as general interferometers. The results obtained are used to confirm the functionality of the simplified micro-fabrication technique for fabricating integrated optical polymer-based sensors and sensor arrays for chemical/biological sensing applications.