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.

Fluorinated norbornene monomers exhibit the requisite properties for inclusion in 157 nm photoresists, but traditional addition and radical polymerizations with these monomers have failed. Norbornanediols provide an alternate route to these materials via condensation polymerization, and methods have been developed for the efficient synthesis of the exo-2-syn-7- and endo-2-exo-3-dihydroxynorbornanes. Synthesis of the fluorinated analogues is complicated by steric and electronic effects; however, a high-yielding synthesis of endo-2-exo-3-dihydroxynorbornane bearing a 5-endo-[2,2-bis(trifluoromethyl)hydroxyethyl] substituent as well as its corresponding polymer are reported. As an alternative to 157 nm and other optical lithographies, Step and Flash Imprint Lithography, or S-FIL®, was introduced in 1999 by The University of Texas at Austin. It has proven to be a cost effective, high resolution alternative to traditional optical lithography. Often in the S-FIL process, residual resist may become imbedded within the template features resulting in device defects due to the imprint and repeat nature of S-FIL. The high silicon and cross-linking content of the resist formulations are extremely difficult, if not impossible to remove from quartz imprint mold without template degradation. Our approach to this problem was the synthesis of a family of thermally reversible, cross-linkable monomers that will facilitate resist removal while maintaining template integrity. Our monomers utilize classic Diels-Alder chemistry to provide thermal reversibility, while pendant acrylate functionalities facilitate cross-linking. Herein we report the synthesis of several Diels-Alder compounds, incorporate them into resist formulations, and test their efficacy for resist removal. In an effort to develop unique patternable materials, our laboratory is currently engaged in the design and development of photonic crystals comprised of organic elements with highly stable electro-optic activity. Fabrication of these devices requires polymers that can be patterned at high resolution, have large second order nonlinear optical (NLO) coefficients, and that are thermally stable after poling. Our route to these materials involves the synthesis of a prepolymer that can be spin coated, poled, and then fixed by a photochemical cross-linking reaction. We now describe an efficient synthetic route to a new class of biscross-linkable monomers and the characteristics of their corresponding nonlinear optical polymers. / text

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The capability to easily and inexpensively fabricate microfluidic devices with negligible dependence on specialized laboratory equipment continues to be one of the primary forces driving the widespread use of plastic-based devices. These devices are typically produced as replicas of a rigid mold or master incorporating a negative image of the desired structures. The negative image is typically constructed from either thick photoresists or etched silicon substrates using conventional photolithographic fabrication processes. While these micromachining techniques are effective in constructing masters with micron-sized features, the need to produce masters rapidly in order to design, fabricate, and test microfluidic devices, is a major challenge in microfluidic technology. In this research, we use inexpensive photosensitized copper clad circuit board substrates to produce master molds using conventional printed circuit technology. The techniques provide the benefits of parallel fabrication associated with photolithography without the need for cleanroom facilities, thereby offering a degree of speed and simplicity that allows microfluidic master molds to be constructed in approximately 30 minutes in any laboratory. These techniques are used to produce a variety of microfluidic channel networks using PDMS (polydimethylsiloxane) and melt-processable plastic materials.

This thesis describes the study of a variety of nanoscale materials and the development of novel synthetic strategies for their production. While the focus and bulk of this study have been directed specifically at subwavelength lithography, a significant portion of this thesis research involves nanoparticle synthesis, characterization, and functionalization. Put in very simple terms, optical lithography is a process where a beam of light, focused in a specific pattern, is used to generate a physical pattern on a solid substrate. This technology forms the basis for almost all microchip production in the world at the present time. As demand for faster and more powerful chips increases, the need to further miniaturize the patterns while minimizing cost has become very important. Multiple photochemical systems were developed in the search for non-reciprocal photochemistry at 193 nm to increase the resolution of lithographic processes at that wavelength. One approach, based on anthracene sensitization of sulfonium salts for acid generation, used photochemically reversible 4+4 aromatic cycloaddition reactions to introduce the non-linear photochemistry. A second approach took advantage of the photochemistry of N-methylphenothiazine and provided the first true example of a lithographically-relevant multi-photon acid generating process. Since all of the systems we studied used sulfonium salts as the acid generating species, we also looked at the photochemistry of the salts themselves. We evaluated the structural effects of the salts on their direct photochemistry and the implications for sensitized multi-photon photochemistry. We found that the identity of the anion plays a significant role in both processes and propose a new photochemical mechanism for acid generation that involves a charge transfer excitation process. We also describe the synthesis and characterization of novel fluorescent silver nanoparticles, both in solution and polymer films. We show that the fluorescent images can be patterned easily and preliminary results show that photolithography based on nanoparticle formation may be possible. This latter approach could provide a facile route to nanoparticle-embedded functional materials. This work with nanoparticles was inspired partly by earlier work, also presented herein, on semiconductor nanoparticles and their interactions with disulfide ligands.

This thesis describes the study of a variety of nanoscale materials and the development of novel synthetic strategies for their production. While the focus and bulk of this study have been directed specifically at subwavelength lithography, a significant portion of this thesis research involves nanoparticle synthesis, characterization, and functionalization. Put in very simple terms, optical lithography is a process where a beam of light, focused in a specific pattern, is used to generate a physical pattern on a solid substrate. This technology forms the basis for almost all microchip production in the world at the present time. As demand for faster and more powerful chips increases, the need to further miniaturize the patterns while minimizing cost has become very important. Multiple photochemical systems were developed in the search for non-reciprocal photochemistry at 193 nm to increase the resolution of lithographic processes at that wavelength. One approach, based on anthracene sensitization of sulfonium salts for acid generation, used photochemically reversible 4+4 aromatic cycloaddition reactions to introduce the non-linear photochemistry. A second approach took advantage of the photochemistry of N-methylphenothiazine and provided the first true example of a lithographically-relevant multi-photon acid generating process. Since all of the systems we studied used sulfonium salts as the acid generating species, we also looked at the photochemistry of the salts themselves. We evaluated the structural effects of the salts on their direct photochemistry and the implications for sensitized multi-photon photochemistry. We found that the identity of the anion plays a significant role in both processes and propose a new photochemical mechanism for acid generation that involves a charge transfer excitation process. We also describe the synthesis and characterization of novel fluorescent silver nanoparticles, both in solution and polymer films. We show that the fluorescent images can be patterned easily and preliminary results show that photolithography based on nanoparticle formation may be possible. This latter approach could provide a facile route to nanoparticle-embedded functional materials. This work with nanoparticles was inspired partly by earlier work, also presented herein, on semiconductor nanoparticles and their interactions with disulfide ligands.

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.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Gonzalo Arce, Dept. of Electrical & Computer Engineering. Includes bibliographical references.

Currently, the imprint lithography steppers are designed to only pattern one field of 26 x 33 mm at a time. This choice is based on the desire to mix-and-match to the standard optical lithography tools whose field size is also 26 x 33 mm. Throughput can be increased if more than one field can be imprinted simultaneously. The problem with adding a field to the imprinting template is that each field has overlay errors associated with it that are created when the template is manufactured and when the corresponding prior field is manufactured on the wafer. The current process is able to correct these template and wafer overlay errors using a precision stage and actuators that elastically deform the template. The same method cannot be used when there are two fields because the fields are not independent and interact with each other. Correcting the errors in one of the fields tend to increase the error in the second field. vii In this thesis, a new control method has been created to account for the dependent motion. A new template concept was also created to try to limit the interaction between the two fields. The new control algorithm was tested in simulation to see if it could correct the current 1-field setup as well as the new concept of having more than one field on a template. The control algorithm was also used to test applications where the overlay errors in only one direction need to be corrected. The control algorithm was tested on a solid single field template, the baseline case, and was able to achieve 1.3 nm overlay, which is consistent with the current method. The algorithm was then tested on the dual field concepts. The range of alignment errors needed to get 5 nm overlay are too tight for current manufacturing but the compliant concept did have more relaxed ranges than the solid dual field template. With more research, the compliant template concept might be changed to allow for wider ranges. The tests with correction in only one direction had promising data that should be investigated further. / text