We have fabricated nanofuses from thin-film, arc-evaporation carbon for use in permanent data storage. Thin film carbon fuses have fewer fabrication barriers and retain the required resistivity and structural stability to work as a data storage medium. Carbon thin films were characterized for their electrical, microstructural, and chemical bonding properties. Annealing the thin-film carbon in an argon environment at 400°C reduced the resistivity from about 4*10-2 Ω cm as deposited down to about 5*10-4 Ω cm, allowing a lower blowing voltage. Nanofuses with widths ranging from 200 nm down to 60 nm were fabricated and tested. They blow with voltages between 2 V and 5.5 V, and the nanofuses remain stable in both a "1" and a "0" state under a constantly applied read voltage of 1 volt for over 90 hours, corresponding to a cumulative time of >1012 reads.

Radiation polymerization is a rapid, sustainable process, requiring no environmentally damaging solvents and less energy than thermal polymerization methods. This process is used extensively each year to produce millions of tons of films, coatings, inks, and adhesives. In this work, kinetic- and property-control strategies were developed for three underdeveloped areas of radiation polymerization: free-radical electron beam (EB) polymerization, free-radical/cationic hybrid photopolymerization, and cationic shadow cure. Raman spectroscopy, an analytical technique for studying photopolymerization kinetics, was established as a method of determining the conversion of EB-initiated polymer films. This technique, in conjunction with dynamic mechanical analysis (DMA), was used to investigate the impact of chemical structure on the magnitude of EB dose rate effects (DREs). A strong correlation was determined between the DRE magnitude and monomer size, which may be attributed to chain transfer opportunities. A preliminary predictive relationship was developed to estimate the magnitude of the DRE using the property shift caused by changes in dose, enabling scale-up of process variables for polymers prone to dose rate effects. In addition, a protocol was developed to produce films with equivalent energy deposition for both EB and photopolymerizations, allowing the effect of the initiating radiation to be studied. Distinct kinetic and physical property differences were shown in the resulting EB- and photo-initiated films, despite equivalent initiation energies and energy rates. Monomer chemistry was determined to be an important factor in the magnitude of these differences. In order to control the phase separation that can occur in free-radical/cationic hybrid systems, the cationic AM mechanism was promoted through a hydroxyl group located on the (meth)acrylate, covalently bonding the (meth)acrylate and epoxide networks. The impact of the AM mechanism on the reaction kinetics and physical properties was studied using real-time Raman spectroscopy and DMA to compare a hydroxyl-containing acrylate and methacrylate to non-hydroxyl-containing controls. The promotion of the AM mechanism improved epoxide conversion and network homogeneity. The affect on the (meth)acrylate kinetics correlated to the propagation rate of the neat (meth)acrylate. It was also demonstrated that the glass transition temperature of the hybrid system could be controlled by varying the ratio of (meth)acrylate to epoxide. Cationic shadow cure, which offers a means of circumventing the light penetration limitations in photopolymerization, was modeled using a central composite design. This model was shown to be predictive of both shadow cure length and gel fraction while varying effective irradiance, exposure time, exposure area, and sample depth. Moreover, the model helped ascertain the impact of each variable and its interactions: shadow cure length was most influenced by sample depth, but the gel fraction was reliant on the other three variables. Active center mobility was also qualitatively tracked, and it was established that the section of solid polymer formed during illumination was restricting the movement of the active centers, preventing complete cure. Through this discovery, a new method of shadow cure was developed, termed transferable shadow cure (TSC). This new method separates the initiation and propagation mechanisms, and, as the name suggests, allows for the active-center-containing monomer to be transferred to areas unreachable by light before solidifying. Conversion of the TSC, as determined via Raman spectroscopy, was also modeled using a central composite design. The model predicts TSC conversion is equally dependent on effective irradiance, sample depth, and exposure time, but independent of exposure area. Through the development of control strategies in these three areas, this work provides a better fundamental understanding of radiation polymerization, as well as guidelines that aid in product design and technology expansion.

Magnetic permalloy nanostructures were fabricated onto a silicon wafer using electron beam lithography and a liftoff process. The lithography was performed with a Hitachi SU-70 SEM retrofitted with a Nabity NPGS lithography conversion kit. PMMA of 950kDa molecular weight was used as the photoresist. Features were either nanowires, nanodots, or elliptical or rectangular nanostructures. The nanowires had dimensions of 15µm x 200nm x 40nm, the nanodots had diameters of 145nm and thickness of 12nm, and the ellipses and rectangles had dimensions of 110nm x 50nm x 13nm. Characterization of the nanostructures was performed using the same Hitachi SEM as well as a Digital Instruments DI 3100 Nanoscope IIIa AFM used in magnetic force imaging mode. The SEM was used to measure lateral dimensions of the features and to capture images of features for proper documentation and for external simulation studies. The MFM was used to capture magnetic images of the samples to determine the magnetic state of the nanowires or arrays.

We report on the process parameters of nanoimprint lithography (NIL) for the fabrication of two-dimensional (2-D) photonic crystals. The nickel mould with 2-D photonic crystal patterns covering the area up to 20mm² is produced by electron-beam lithography (EBL) and electroplating. Periodic pillars as high as 200nm to 250nm are produced on the mould with the diameters ranging from 180nm to 400nm. The mould is employed for nanoimprinting on the poly-methyl-methacrylate (PMMA) layer spin-coated on the silicon substrate. Periodic air holes are formed in PMMA above its glass-transition temperature and the patterns on the mould are well transferred. This nanometer-size structure provided by NIL is subjective to further pattern transfer. / Singapore-MIT Alliance (SMA)

Wood composites are widely used in construction applications because of their superior dimensional and structural attributes over raw wood products. However, current wood composite manufacturing practices, which rely on thermal-curing of adhesives, are expensive, energy intensive, time consuming and are prone to manufacturing defects. Use of radiation curable adhesives (RCAs) could potentially answer all of these issues. Specifically, use of electron-beam (e-beam) radiation has been increasing in areas of research and industry where rapid, low-temperature polymerization is required and low energy consumption is desired. For e-beams to be used in wood composites, however, it must be determined whether or not the wood is structurally impacted by irradiation, and to what extent. Maple beams irradiated with a range of e-beam dosages were studied in three-point bend tests to assess the changes in bulk properties of the wood, and were further studied with infrared spectroscopy to identify chemical changes resulting from the radiation treatments. Also, dynamic mechanical analysis (DMA) was performed on maple veneers treated with the same doses of radiation to characterize changes in the viscoelastic properties. Furthermore, while RCAs and their curing have been studied, it is important to understand if the presence of wood will impede the polymerization of these adhesives, and to what extent. Maple veneers impregnated with one of two resins were cured with the same e-beam dosages and investigated by means of DMA and FTIR spectroscopy. Swelling tests were conducted to detect interaction between the resins and the wood, which would indicate good interfacial bonding in the composite matrix. Notable loss of strength was observed in the irradiated wood, especially at 180kGy. Monitoring the glass transition temperature (Tg) and activation energy (Ea) derived from DMA revealed that the most destructive trends in the wood began around 80kGy. Cure of resins in the composites was hindered by the presence of the wood, but both resins did eventually reach complete cure at doses higher than what the neat resins required. Interaction between the resins and the wood was evident. In the end, results indicate that there is a range of radiation dosages in which the resin in a wood composite can be cured without destroying the structural integrity of the wood.

The field of Information and Communication Technologies is witnessing a development speed unprecedented in history. Moore’s law proves that the processor speed and memory size are roughly doubling each 18 months, which is expected to continue in the next decade. If photonics is going to play a substantial role in the ICT market, it will have to follow the same dynamics. There are mainly two groups of components that need to be integrated. The active components, including light sources, electro-optic modulators, and detectors, are mostly fabricated in III-V semiconductors. The passive components, such as waveguides, resonators, couplers and splitters, need no power supply and can be realized in silicon-related semiconductors. The prospects of silicon photonics are particularly promising, the fabrication is mostly compatible with standard CMOS technology and the on-chip optical interconnects are expected to increase the speed of microprocessors to the next generation. This thesis starts with designs of various silicon-based devices using finite-difference time-domain simulations. Parallel computation is a powerful tool in the modeling of large-scale photonic circuits. High Q cavities and resonant channel drop filters are designed in photonic crystal platform. Different methods to couple light from a single mode fiber to silicon waveguides are studied by coupled-mode theory and verified using parallel simulations. The performance of waveguide grating coupler for vertical radiation is also studied. The fabrication of silicon-based photonic devices involves material deposition, E-beam or optical lithography for pattern defining, and plasma/wet-chemistry etching for pattern transfer. For nanometer-scaled structures, E-beam lithography is the most critical process. Depending on the structures of the devices, both positive resist (ZEP520A) and negative resist (maN2405) are used. The proximity and stitch issues are addressed by careful dose correction and patches exposure. Some examples are given including photonic crystal surface mode filter, micro-ring resonators and gold grating couplers. In particular, high Q (2.6×105), deep notch (40 dB) and resonance-splitting phenomenon are demonstrated for silicon ring resonators. It is challenging to couple light into photonic integrated circuits directly from a single-mode fiber. The butt-coupled light-injecting method usually causes large insertion loss due to small overlap of the mode profiles and large index mismatch. Practically it is not easy to cleave silicon sample with smooth facet where the waveguide exposes. By adding gold gratings to the waveguides, light can be injected and collected vertically from single-mode fiber. The coupling efficiency is much higher. There is no need to cleave the sample. The access waveguides are much shortened and the stitch problem in E-beam lithography is avoided. In summary, this thesis introduces parallel simulations for the design of modern large-scale photonic devices, addresses various issues with Si-based fabrication, and analyses the data from the characterization. Several novel devices using silicon nanowire waveguides and 2D photonic crystal structures have been demonstrated for the first time. / QC 20100923

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Im Rahmen des Symposiums gaben Vertreter weltweit agierender Konzerne, wie Audi AG, voestalpine Gießerei Linz, Alstom AG und SITEC GmbH Einblick in ihre Forschungs­aktivitäten im Bereich Mobilität, Energietechnik, Medizintechnik und Sondermaschinenbau. Die schweißtechnischen Institute der Universitäten Aachen, Braunschweig, Clausthal, Dresden, Magdeburg und Graz gaben einen Überblick über universitäre Forschungs­aktivitäten.

Electron Beam Chemical Vapor Deposition (EBCVD) is a process by which an electron beam is used to decompose adsorbed reagent molecules to produce a deposit. The primary electrons from the beam, and especially the secondary electrons emitted from the substrate, dissociate the adsorbed molecules. Important factors for the deposition process include the beam parameters and reagent gas composition. Simple structures are fabricated through utilization of the various scanning modes of an SEM. Fibers (pillar-like structures) can be deposited, and lines (wall-like structures) can be deposited easily. This investigation focuses on the process parameters controlling deposition rate and geometry for platinum and carbon fibers and lines in a modified SEM. Platinum deposition was performed using a system with a small diameter needle that supplied a localized flow of gas from an organometallic platinum compound. Carbon deposition was performed in the Environmental mode, in which the microscope chamber is filled with a specified pressure of reagent gas. Statistically designed experiments were performed for platinum fiber and line deposition. Analysis indicated that the beam current and deposition time were dominant factors in determining the deposition rate. The voltage also had a significant effect on fiber deposition. For platinum line deposition, the effects of the dwell time and line time were also studied. The line time had a significant effect on line height deposited per scan. Optimization analysis was performed, and results indicated that high voltage and high beam current led to higher aspect ratios. Medium voltage and low beam current were preferable for depositing minimal width lines (less than 200 nm). Low voltage and high beam current were preferable for maximum deposition rates. EDS and EELS performed for platinum deposits in a TEM indicated amorphous structure with no carbon detected. This differs significantly from previously reported results. Statistically designed experiments were performed for carbon line deposition. The voltage, beam current, and dwell/line time were studied. Increasing line time led to a significant increase in line height/scan and appeared to be a dominant factor. Lower beam currents appeared to favor higher deposition rates. TEM analysis indicated that carbon deposits were mostly amorphous.

This thesis reports the characterization and development of nanolithography using Electron Beam Lithography system and nanoscale plasma etching. The standard Bosch process and a modified three-pulse Bosch process were developed in STS ICP and Plasma ICP system separately. The limit of the Bosch process at the nanoscale regime was investigated and documented. Furthermore, the effect of different control parameters on the process were studied and summarized in this report. 28nm-wide trench with aspect-ratio of 25 (smallest trench), and 50nm-wide trench with aspect ratio of 37 (highest aspect-ratio) have been demonstrated using the modified three-pulse process. Capacitive resonators, SiBAR and IBAR devices have been fabricated using the process developed in this work. IBARs (15MHz) with ultra-high Q (210,000) have been reported.