The image quality and collimation in a multiple-optical-axis pattern-integrated interference lithography system are evaluated for an elementary optical system composed of single-element lenses. Image quality and collimation are individually and jointly optimized for these lenses. Example images for a jointly optimized system are simulated using a combination of ray tracing and Fourier analysis. Even with these non-optimized components, reasonable fidelity is shown to be possible.

Thesis (M.S.)--Rochester Institute of Technology, 2005. / Typescript. Includes bibliographical references (leaves 94-102).

This dissertation focuses on two aspects of integrating near-infrared plasmonics with electronics with the intent of developing the platform for future photonics. The first aspect focuses on fabrication by introducing and developing a simple, single reflective optical element capable of high–throughput, large scale fabrication of micro- and nano-sized structure templates using holographic lithography. This reflective optical element is then utilized to show proof of concept in fabricating three dimensional structures in negative photoresists as well as tuning subwavelength features in two dimensional compound lattices for the fabrication of dimer and trimer antenna templates. The second aspect focuses on the study of aluminum zinc oxide (AZO), which belongs to recently popularized material class of transparent conducting oxides, capable of tunable plasmonic capabilities in the near-IR regime. Holographic lithography is used to pattern an AZO film with a square lattice array that are shown to form standing wave resonances at the interface of the AZO and the substrate. To demonstrate device level integration the final experiment utilizes AZO patterned gratings and measures the variation of diffraction efficiency as a negative bias is applied to change the AZO optical properties. Additionally efforts to understand the behavior of these structures through optical measurements is complemented with finite difference time domain simulations.

In this dissertation, I am presenting my research on the fabrication and simulation of the optical properties of 3D photonic crystals and 2D graded photonic super-crystals. The 3D photonic crystals were fabricated using holographic lithography with a single, custom-built reflective optical element (ROE) and single exposure from a visible light laser. Fully 3D photonic crystals with 4-fold, 5- fold, and 6-fold symmetries were fabricated using the flexible, 3D printed ROE. In addition, novel 2D graded photonic super-crystals were fabricated using a spatial light modulator (SLM) in a 4f setup for pixel-by-pixel phase engineering. The SLM was used to control the phase and intensity of sets of beams to fabricate the 2D photonic crystals in a single exposure. The 2D photonic crystals integrate super-cell periodicities with 4-fold, 5-fold, and 6-fold symmetries and a graded fill fraction. The simulations of the 2D graded photonic super-crystals show extraordinary properties such as full photonic band gaps and cavity modes with Q-factors of ~106. This research could help in the development of organic light emitting diodes, high-efficiency solar cells, and other devices.

No description available.

The fifth and sixth generations of mobile communications and the internet of things (IoT) demand high-performance electronic devices made at low cost over a large area. Unlike the conventional Si-based electronics, the emerging large-area electronics (LAE) require flexible, stretchable, and lightweight devices that are printable and able to mass manufacture without compromising the performance of state-of-the-art electronic devices. Hence, there is a quest to find alternative fabrication routes and conventional photolithography. In this research work, we explored the adhesion lithography (a-Lith) to further simplify the process steps by adapting bi-layer metals to induce intrinsic stress in the bi-layer and hence facilitate the self-peeling of metal layers which results in more uniform and smaller nanogap between two metals than the previously established a-Lith fabricated nanogaps. The nanogap metal electrodes are further used to fabricate radio frequency (RF) Schottky diodes made using a printable metal oxide semiconductor and flashlight annealing over wafer-scale and demonstrate the operation frequencies above 100 GHz/47 GHz (intrinsic/extrinsic). Notably, for the first time, photonic annealing on such an ultra-small (< 20 nm) nanoscale channel was demonstrated, and the rapid manufacturing of RF diodes from the solution route was achieved. On the other hand, for the first time, organic diodes made using a-Lith fabricated nanogap metal electrodes, and high mobility polymer semiconductors with molecular dopants showed an extrinsic cut-off frequency well above 14 GHz. Finally, the nanogap metal electrodes were explored as a mold and shadow mask to fabricate nano-feature soft stamp and nano-fluidic channels (NFC), respectively. The soft stamp can replicate the high aspect ratio nanoscale features on any arbitrary substrates using available soft lithography routes, and the NFC is further envisioned for bio-molecules detection and sensing applications.

No description available.

<p> 3D printing has established itself as a critical tool for manufacturing in all areas. It has evolved from a purely rapid prototyping technique into a feasible process for large-scale processing. A wide variety of 3D printing processes exist across an extreme range of size, from meters to nanometers. Much of the current technological advances come from pushing fabrication techniques to smaller and smaller scales. For 3D printing this has led to the rise of two-photon polymerization, a direct laser writing process with submicron structuring capabilities. Two-photon polymerization has proven its worth as a nanoscale 3D fabrication technique but is often considered slow and expensive, two undesirable qualities for high throughput manufacturing. Parallelization methods such as projection lithography are potential solutions to increasing the throughput capabilities of two-photon polymerization 3D printing. Additionally, the drive for further reducing the print size has inspired printing resolution enhancing strategies in two-photon polymerization printing by processes such as stimulated emission depletion (STED) and other STED-inspired pathways. This work will explore avenues for improving two-photon polymerization printing throughput and resolution.</p> <p> First, a two-photon polymerization printing system is constructed with a secondary laser for controlling polymerization inhibition. Through a STED process, a 65 nm wide printed line feature was achieved. Alongside this, a characterization and verification methodology for choosing new photoinitiator molecules for similar inhibition lithography processes is presented. Through implementation of tests such as Z-scan, fluorescence depletion, ultrafast transient spectroscopy and UV-Vis absorption and fluorescence measurements a promising new photoinitiator with 5-factor improvement in printing efficiency is found. </p> <p> Second, a projection lithography scheme is developed for rapid two-photon 3D printing. A digital micro-mirror device (DMD) is utilized for dynamic pattern generation and the effects of its dispersion properties are considered. Through a spatiotemporal focusing process, continuous 3D printing is achieved at vertical prints speeds of 1 mm s-1. Simulations performed representing this rapid printing process indicate a ~1 µm layer print feature size for large areas of exposure. Comparably, a printed vertical feature size of ~ 1 µm was achieved. Lateral feature sizes ~200 nm were also demonstrated in fabrication. A variety of complex 3D structures are printed for demonstration of the spatiotemporal focusing projection lithography process including millimeter scale objects with micrometer scale 3D features.</p> <p> Finally, resolution enhancing strategies are implemented into the continuous, projection two-photon lithography technique. An investigation of the inhibition properties of a variety of photoinitiator systems for inhibiting polymerization achieved with low repetition rate laser exposure is presented. A planar polymerization inhibiting region is generated by creating a light sheet propagating perpendicularly to the projection printing plane. </p>

In this thesis, different approaches in synthesizing molecular resist are examined, and structure-property relations for the molecular resist properties are studied. This allows for design of resists that could be studied further as either negative or positive tone resists in photolithography. A series of compounds having different number of acrylate moiety, and different backbones were investigated for photoresist application. Thermal curing of acrylate compounds in organic solvent was also examined. Film shrinkage, as well as auto-polymerization was observed for these compounds that make them unsuitable as photoresist material. Furthermore, calix[4]resorcinarenes (C4MR) was chosen as backbone, and the functional groups was selected as oxetane and epoxy. Full functionalized C4MR compounds with oxetane, epoxy and allyl were synthesized. Variable-temperature NMR of C4MR-8Allyl was studied in order to get a better understanding of the structure’s conformers. Energy barrier of exchange (ΔG#) was determined from coalescence temperatures, and was 57.4 KJ/mol for aromatic and vinyl hydrogens and 62.1 KJ/mol for allylic hydrogens.

Modeling of engineering objects with complex heterogeneous material structure at nanoscale level has emerged as an important research problem. In this research, we are interested in multiscale modeling and analysis of mechanical properties of the polymer structures created in the Step and Flash Imprint Lithography (SFIL) process. SFIL is a novel imprint lithography process designed to transfer circuit patterns for fabricating microchips in low-pressure and room-temperature environments. Since the smallest features in SFIL are only a few molecules across, approximating them as a continuum is not completely accurate. Previous research in this subject has dealt with coupling discrete models with continuum hyperelasticity models. The modeling of the post-polymerization step in SFIL involves computing solutions of large nonlinear energy minimization problems with fast spatial variation in material properties. An equilibrium configuration is found by minimizing the energy of this heterogeneous polymeric lattice. Numerical solution of such a molecular statics base model, which is assumed to describe the microstructure completely, is computationally very expensive. This is due to the problem size – on the order of millions of degrees of freedom (DOFs). Rapid variation in material properties, ill-conditioning, nonlinearity, and non-convexity make this problem even more challenging to solve. We devise a method for efficient approximation of the solution. Combining numerical homogenization, adaptive finite element meshes, and goaloriented error estimation, we develop a black-box method for efficient solution of problems with multiple spatial scales. The purpose of this homogenization method is to reduce the number of DOFs, find locally optimal effective material properties, and do goal-oriented mesh refinement. In addition, it smoothes the energy landscape. Traditionally, a finite element mesh is designed after obtaining material properties in different regions. The mesh has to resolve material discontinuities and rapid variations. In our approach, however, we generate a sequence of coarse meshes (possibly 1-irregular), and homogenize material properties on each coarse mesh element using a locally posed constrained convex quadratic optimization problem. This upscaling is done using Moore-Penrose pseudoinverse of the linearized fine-scale element stiffness matrices, and a material independent interpolation operator. This requires solution of a continuous-time Lyapunov equation on each element. Using the adjoint solution, we compute local error estimates in the quantity of interest. The error estimates also drive the automatic mesh adaptivity algorithm. The results show that this method uses orders of magnitude fewer degrees of freedom to give fast and approximate solutions of the original fine-scale problem. Critical to the computational speed of local homogenization is computing Moore-Penrose pseudoinverse of rank-deficient matrices without using Singular Value Decomposition. To this end, we use four algorithms, each having different desirable features. The algorithms are based on Tikhonov regularization, sparse QR factorization, a priori knowledge of the null-space of the matrix, and iterative methods based on proper splittings of matrices. These algorithms can exploit sparsity and thus are fast. Although the homogenization method is designed with a specific molecular statics problem in mind, it is a general method applicable for problems with a given fine mesh that sufficiently resolves the fine-scale material properties. We verify the method using a conductivity problem in 2-D, with chessboard like thermal conductivity pattern, which has a known homogenized conductivity. We analyze other aspects of the homogenization method, for example the choice of norm in which we measure local error, optimum coarse mesh element size for homogenizing SFIL lattices, and the effect of the method chosen for computing the pseudoinverse. / text