Nanofabrication is the process of making functional structures with arbitrary patterns having nanoscale dimensions. Nanofabrication has been widely implemented in industry for improving microelectronic devices and data storage technology, to increase the component density, to lower the cost and to increase the performance. Other areas of applications include optics, cell biology and biomedicine. One of the most critical challenges in the development of next generation nanoscale devices is the rapid, parallel, precise and robust fabrication of nanostructures. In this thesis work, we demonstrate the possibility to parallelize the thermochemical nanolithography (TCNL) by creating nanoscale patterns with a tip array, containing five identical thermal cantilevers. The versatility of our technique is demonstrated by creating nanopatterns simultaneously on multiple surfaces, including graphene oxide and conjugated polymers. This work also involves the study of the reduction process of graphene fluoride through TCNL and the study of the local anodic oxidation of epitaxial graphene, to create high quality graphene nanoribbons.

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A system for the patterning of amines through the thermal decomposition of a thin polymer film was proposed. The polymer was synthesized and films were produced by spin coating. The pyrolysis of both the polymer and the films was studied. The physical properties of the film, such as Tg, were controlled through crosslinking of the polymer and the crosslinking conditions were optimized. Analyses of the reactions that occur on the film as a result of thermal decomposition were studied. These studies seem to indicate that the thin film system studied is viable option toward the patterning of amines. The ability to bind material to the polymer films after deprotection was demonstrated using fluorescent protein and fluorescein isothiocyanate. Micron scale patterns of these fluorescent molecules were created and imaged, successfully demonstrating the viability of the system for patterning. Patterns of polyphenylene vinlyene were produced through the thermal decomposition of a tetrahydrothiophenium chloride salt precursor. Images of the patterns were obtained.

This dissertation contains two different research topics. One is a ‘Nano Scale Device for Plasmonic Nanolithography – Optical Antenna’ and the other is a ‘Nano Scale Device for Rapid Sensing of Bacteria – SEPTIC’. Since these two different research topics have little analogy to each other, they were divided into different chapters throughout the whole dissertation. The ‘Optical Antenna’ and ‘Nanowell / Microwell / ISFET Sensor’ represent the device names of each topic ‘Plasmonic Nanolithography’ and ‘Rapid Sensing of Bacteria’, respectively. For plasmonic nanolithography, we demonstrated a novel photonic device - Optical Antenna (OA) - that works as a nano scale object lens. It consists of a number of sub-wavelength features in a metal film coated on a quartz substrate. The device focuses the incident light to form a narrow beam in the near-field and even far-field region. The narrow beam lasts for up to several wavelengths before it diverges. We demonstrated that the OA was able to focus a subwavelength spot with a working distance (also the focal length) of several µm, theoretically and experimentally. The highest imaging resolution (90-nm spots) is more than a 100% improvement of the diffraction limit (FWHM = 210 nm) in conventional optics. A model and 3D electromagnetic simulation results were also studied. Given its small footprint and subwavelength resolution, the PL holds great promise in direct-writing and scanning microscopy. Collaborative work demonstrated a Nanowell (or Microwell) device which enables a rapid and specific detection of bacteria using nano (or micro) scale probe to monitor the electric field fluctuations caused by ion leakage from the bacteria. When a bacteriophage infects a bacterium and injects its DNA into the host cell, a massive and transitory ion efflux from the host cell occurs. SEPTIC (SEnsing of Phage-Triggered Ion Cascade) technology developed by collaboration uses a nanowell device to detect the nano-scale electric field fluctuations caused by this ion efflux. The SEPTIC provides fast (within several minutes), effective (living cell only), phage specific (simple and less malfunction), cheap, compact and robust method for bacteria sensing. We fabricated a number of devices, including ‘Nanowell’, ‘Microwell’, and ‘ISFET (Ion Selective Field Effect Transistor)’, which detect bacteria-phage reactions in frequency domain and time domain. In the frequency domain, detected noise spectrum is characterized by β f / 1 . The positive reaction showed much higher 1 ≅ β than that of background noise or negative reaction ( 0 ≅ β ). For the time domain, we observed abnormal pulses (> σ 8 ) lasting 0.1 ~ 0.3 s which match the duration of ion flux reported by prior literatures. And the ISFET showed the phage-infection-triggered pulse in the form of the deviated drain current. Given the size of nanowell (or microwell, ISFET) and the simplified detection electronics, the cost of bacteria sensing is significantly reduced and the robustness is well improved, indicating very promising applications in clinical diagnosis and bio-defense.

Scanning Probe Lithography (SPL) is a versatile nanofabrication platform that leverages microfluidic “ink” delivery systems with Scanning Probe Microscopy (SPM) for generating surface-patterned chemical functionality on the sub-100 nm length scale. One of the prolific SPL techniques is Dip Pen Nanolithography™ (DPN™). High resolution, multiplexed registration and parallel direct-write capabilities make DPN (and other SPL techniques) a power tool for applications that are envisioned in micro/nano-electronics, molecular electronics, catalysis, cryptography (brand protection), combinatorial synthesis (nano-materials discovery and characterization), biological recognition, genomics, and proteomics. One of the greatest challenges for the successful performance of the DPN process is the delivery of multiple inks to the scanning probe tips for nano-patterning. The purpose of the present work is to fabricate a microfluidic ink delivery device (called “Centiwell”) for DPN (and other SPL) applications. The device described in this study maximizes the number of chemical species (inks) for nanofabrication that can be patterned simultaneously by DPN to conform the industrial standards for fluid handling for biochemical assays (e.g., genomic and proteomic). Alternate applications of Centiwell are also feasible for the various envisioned applications of DPN (and other SPL techniques) that were listed above. The Centiwell consists of a two-dimensional array of 96 microwells that are bulk micromachined on a silicon substrate. A thermoelectric module is attached to the back side of the silicon substrate and is used to cool the silicon substrate to temperatures below the dew point. By reducing the temperature of the substrate to below the dew point, water droplets are condensed in the microwell array. Microbeads of a hygroscopic material (e.g., poly-ethylene glycol) are dispensed into the microwells to prevent evaporation of the condensed water. Furthermore, since poly-ethylene glycol (PEG) is water soluble, it forms a solution inside the microwells which is subsequently used as the ink for the DPN process. The delivery of the ink to the scanning probe tip is performed by dipping the tip (or multiple tips in an array) into the microwells containing the PEG solution. This thesis describes the various development steps for the Centiwell. These steps include the mask design, the bulk micromachining processes explored for the micro-fabrication of the microwell array, the thermal design calculations performed for the selection of the commercially available thermoelectric coolers, the techniques explored for the synthesis of the PEG microbeads, and the assembly of all the components for integration into a functional Centiwell. Finally, the successful implementation of the Centiwell for nanolithography of PEG solutions is also demonstrated.

This dissertation contains two different research topics. One is a "Nano Scale Device for Plasmonic Nanolithography - Optical Antenna' and the other is a 'Nano Scale Device for Rapid Sensing of Bacteria - SEPTIC'. Since these two different research topics have little analogy to each other, they were divided into different chapters throughout the whole dissertation. The 'Optical Antenna' and 'Nanowell / Microwell / ISFET Sensor' represent the device names of each topic 'Plasmonic Nanolithography' and 'Rapid Sensing of Bacteria' respectively. For plasmonic nanolithography, we demonstrated a novel photonic device - Optical Antenna (OA) - that works as a nano scale object lens. It consists of a number of sub-wavelength features in a metal film coated on a quartz substrate. The device focuses the incident light to form a narrow beam in the near-field and even far-field region. The narrow beam lasts for up to several wavelengths before it diverges. We demonstrated that the OA was able to focus a subwavelength spot with a working distance (also the focal length) of several µm, theoretically and experimentally. The highest imaging resolution (90-nm spots) is more than a 100% improvement of the diffraction limit (FWHM = 210 nm) in conventional optics. A model and 3D electromagnetic simulation results were also studied. Given its small footprint and subwavelength resolution, the PL holds great promise in direct-writing and scanning microscopy. Collaborative work demonstrated a Nanowell (or Microwell) device which enables a rapid and specific detection of bacteria using nano (or micro) scale probe to monitor the electric field fluctuations caused by ion leakage from the bacteria. When a bacteriophage infects a bacterium and injects its DNA into the host cell, a massive and transitory ion efflux from the host cell occurs. SEPTIC (SEnsing of Phage-Triggered Ion Cascade) technology developed by collaboration uses a nanowell device to detect the nano-scale electric field fluctuations caused by this ion efflux. The SEPTIC provides fast (within several minutes), effective (living cell only), phage specific (simple and less malfunction), cheap, compact and robust method for bacteria sensing. We fabricated a number of devices, including 'Nanowell', 'Microwell' and 'ISFET (Ion Selective Field Effect Transistor)', which detect bacteria-phage reactions in frequency domain and time domain. In the frequency domain, detected noise spectrum is characterized by 1/f[beta]. The positive reaction showed much higher [beta] =̃1 than that of background noise or negative reaction ( [beta] =̃0). For the time domain, we observed abnormal pulses (> 8[omega] ) lasting 0.1 ~ 0.3 s which match the duration of ion flux reported by prior literatures. And the ISFET showed the phage-infection-triggered pulse in the form of the deviated drain current. Given the size of nanowell (or microwell, ISFET) and the simplified detection electronics, the cost of bacteria sensing is significantly reduced and the robustness is well improved, indicating very promising applications in clinical diagnosis and bio-defense.

This thesis concerns development and characterization of the FEBID technique to improve interfacial properties at MWCNT/graphene-metal junctions by forming graphitic nanojoints using hydrocarbon precursors. A fabrication protocol for ultralow-resistant, Ohmic contacts at MWCNT-metal junctions with FEBID graphitic nanojoints was developed, based on an in-depth topological/ compositional/electrical material characterization, yielding high performance “end” contacts to multiple conducting channels of MWCNT interconnect. Using the FEBID technique as a contact fabrication tool, three fabrication strategies of electrical contacts between the mechanically exfoliated multilayer graphene and a metal interconnect using graphitic nanojoints were proposed and demonstrated experimentally, suggesting one of them, the post-deposited FEBID graphitic interlayer formation, as the most efficient strategy. A patterned CVD grown monolayer graphene, which is a promising material for large area graphene device fabrication, was contacted to metal electrodes through the FEBID graphitic interlayer, whose formation and chemical coupling to graphene and metal were theoretically and experimentally explored. The effects of FEBID process on the graphitic interlayer formation and graphene electronic devices were demonstrated through electrical measurements, including the transmission line method (TLM) measurements for separate evaluation of sheet and contact resistances. Modifications of the graphene channel as well as interfacial properties of the graphene-metal junctions were achieved, highlighting a unique promise of the FEBID technique as a tool for enhancing chemical, thermo-mechanical, and electrical properties of graphene-metal interfaces along with controllable tuning of doping states of the graphene channel.

Scanning probe microscopy (SPM) nanolithography has been found to be a powerful and low-cost approach for sub-100 nm patterning. In this thesis, the possibility of using a state-of-the-art SPM system to controllably deposit nanoparticles on patterned Si substrates with high positional control has been explored. These nanoparticles have a range of interesting properties and have been characterised by electron microscopy and scanning probe microscopy. The influence of different deposition parameters on the nanoparticle properties was studied. Contact mode atomic force microscopy (AFM)-based local oxidation nanolithography (LON) was used to oxidise sample surfaces. Two different substrates were studied which were native oxide silicon (Si) and molybdenum (Mo). A number of factors that influence the height and width of the oxide features were investigated in order to achieve the optimal oxidation efficiency. The height and width of the oxide structures were found to be strongly dependent on the applied voltage and scan speed. The tunneling AFM (TUNA) technique was used to measure the ultralow currents flowing between the tip and the sample during the oxidation process. It was found that a threshold voltage for our oxidation experiments was -4.0 ± 1.6 V applied to the tip when fabricating geometric patterns as well as 2.9 ± 1.6 V and 2.8 ± 2.2 V applied to the substrate for nanodot fabrication. In addition, comparisons of nanodot-array patterns produced with different AFM tips were studied. The influence of applied voltage, type of AFM tip and substrate, humidity and ramping time has been studied for dot formation providing a comparison between native oxide Si and Mo surfaces. The nanodot sizes were found to be clearly dependent on the applied voltage, type of substrate, relative humidity and ramping time. Dip-pen nanolithography (DPN) was used to study a direct deposition strategy for gold (Au) nanodot fabrication on a native oxide Si substrate. In this process, hydrogen tetrachloroaurate (HAuCl4) molecules were deposited onto the substrate via a molecular diffusion process, in the absence of electrochemical reactions. This approach allowed for the generation of Au dots on the SiO2 substrate without the need for surface modification or additional electrode structures. The dependence of the size of the Au dots on different „scanning coating‟ (SC) times of AFM tips was studied. A thermal annealing process was used to decompose the generated HAuCl4 molecular dots to leave Au (0) metal dots. A stereomicroscope has been used for preliminary observation of different steps of Au deposition treatments. A scanning electron microscope (SEM) was used to characterise the SC AFM tips both before and after the DPN process. SEM energy-dispersive X-ray spectroscopy (EDS) has provided information about the elemental content of deposited particles for different annealing temperatures. Fountain-pen nanolithography (FPN) has also been used to study nanowriting of HAuCl4 salt and a variety of solvents on a native oxide Si surface. In this technique, a nanopipette was mounted within an AFM to deliver appropriate solutions to the silica substrate. We found that an aqueous Au salt solution was the most suitable ink for depositing gold using the FPN technique. In the case of solvents alone, ethanol and toluene were achieved with depositing onto a SiO2 substrate using the FPN technique.

Nanoscale science and technology demand novel approaches and new knowledge to further advance. Nanoscale fabrication has been widely employed in both modern science and engineering. Micro/nano lithography is the most common technique to deposit nanostructures. Fundamental research is also being conducted to investigate structural, physical and chemical properties of the nanostructures. This research contributes fundamental understanding in surface science through development of a new methodology. Doing so, experimental approaches combined with energy analysis were carried out. A delicate hardware system was designed and constructed to realize the nanometer scale lithography. We developed a complete process, namely laser-assisted scanning probe alloying nanolithography (LASPAN), to fabricate well-defined nanostructures in gold-silicon (Au-Si) system. As a result, four aspects of nanostructures were made through different experimental trials. A non-equilibrium phase (AuSi3) was discovered, along with a non-equilibrium phase diagram. Energy dissipation and mechanism of nanocrystalization in the process have been extensively discussed. The mechanical energy input and laser radiation induced thermal energy input were estimated. An energy model was derived to represent the whole process of LASPAN.