Download or read book The Fabrication of Silicon Nanostructures Using Metal assisted Chemical Etching and Their Applications in Biomedicine written by Hashim Ziad Alhmoud and published by . This book was released on 2015 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main aim of this thesis was to develop novel nano-scale silicon structures with useful functions for biomedicine. Metal-assisted chemical etching (MACE) of silicon offered low fabrication cost, ease of implementation, and an inherent compatibility with various patterning technologies. For these reasons, MACE was used as the primary platform of fabrication for this work. Furthermore, nanostructure patterning was mainly carried out via self-assembled nanosphere lithography, which is a low-cost and reliable method for patterning surfaces on the sub-micrometer scale.

Download or read book Micro and Nano Fabrication by Metal Assisted Chemical Etching written by Lucia Romano and published by MDPI. This book was released on 2021-01-13 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal-assisted chemical etching (MacEtch) has recently emerged as a new etching technique capable of fabricating high aspect ratio nano- and microstructures in a few semiconductors substrates—Si, Ge, poly-Si, GaAs, and SiC—and using different catalysts—Ag, Au, Pt, Pd, Cu, Ni, and Rh. Several shapes have been demonstrated with a high anisotropy and feature size in the nanoscale—nanoporous films, nanowires, 3D objects, and trenches, which are useful components of photonic devices, microfluidic devices, bio-medical devices, batteries, Vias, MEMS, X-ray optics, etc. With no limitations of large-areas and low-cost processing, MacEtch can open up new opportunities for several applications where high precision nano- and microfabrication is required. This can make semiconductor manufacturing more accessible to researchers in various fields, and accelerate innovation in electronics, bio-medical engineering, energy, and photonics. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on novel methodological developments in MacEtch, and its use for various applications.

Download or read book Development of Metal assisted Chemical Etching as a 3D Nanofabrication Platform written by Owen James Hildreth and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The considerable interest in nanomaterials and nanotechnology over the last decade is attributed to Industry's desire for lower cost, more sophisticated devices and the opportunity that nanotechnology presents for scientists to explore the fundamental properties of nature at near atomic levels. In pursuit of these goals, researchers around the world have worked to both perfect existing technologies and also develop new nano-fabrication methods; however, no technique exists that is capable of producing complex, 2D and 3D nano-sized features of arbitrary shape, with smooth walls, and at low cost. This in part is due to two important limitations of current nanofabrication methods. First, 3D geometry is difficult if not impossible to fabricate, often requiring multiple lithography steps that are both expensive and do not scale well to industrial level fabrication requirements. Second, as feature sizes shrink into the nano-domain, it becomes increasingly difficult to accurately maintain those features over large depths and heights. The ability to produce these structures affordably and with high precision is critically important to a number of existing and emerging technologies such as metamaterials, nano-fluidics, nano-imprint lithography, and more. Summary To overcome these limitations, this study developed a novel and efficient method to etch complex 2D and 3D geometry in silicon with controllable sub-micron to nano-sized features with aspect ratios in excess of 500:1. This study utilized Metal-assisted Chemical Etching (MaCE) of silicon in conjunction with shape-controlled catalysts to fabricate structures such as 3D cycloids, spirals, sloping channels, and out-of-plane rotational structures. This study focused on taking MaCE from a method to fabricate small pores and silicon nanowires using metal catalyst nanoparticles and discontinuous thin films, to a powerful etching technology that utilizes shaped catalysts to fabricate complex, 3D geometry using a single lithography/etch cycle. The effect of catalyst geometry, etchant composition, and external pinning structures was examined to establish how etching path can be controlled through catalyst shape. The ability to control the rotation angle for out-of-plane rotational structures was established to show a linear dependence on catalyst arm length and an inverse relationship with arm width. A plastic deformation model of these structures established a minimum pressure gradient across the catalyst of 0.4 - 0.6 MPa. To establish the cause of catalyst motion in MaCE, the pressure gradient data was combined with force-displacement curves and results from specialized EBL patterns to show that DVLO encompassed forces are the most likely cause of catalyst motion. Lastly, MaCE fabricated templates were combined with electroless deposition of Pd to demonstrate the bottom-up filling of MaCE with sub-20 nm feature resolution. These structures were also used to establish the relationship between rotation angle of spiraling star-shaped catalysts and their center core diameter. Summary In summary, a new method to fabricate 3D nanostructures by top-down etching and bottom-up filling was established along with control over etching path, rotation angle, and etch depth. Out-of-plane rotational catalysts were designed and a new model for catalyst motion proposed. This research is expected to further the advancement of MaCE as platform for 3D nanofabrication with potential applications in thru-silicon-vias, photonics, nano-imprint lithography, and more.

Download or read book Micro and Nano Fabrication by Metal Assisted Chemical Etching written by Lucia Romano and published by . This book was released on 2021 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal-assisted chemical etching (MacEtch) has recently emerged as a new etching technique capable of fabricating high aspect ratio nano- and microstructures in a few semiconductors substrates--Si, Ge, poly-Si, GaAs, and SiC--and using different catalysts--Ag, Au, Pt, Pd, Cu, Ni, and Rh. Several shapes have been demonstrated with a high anisotropy and feature size in the nanoscale--nanoporous films, nanowires, 3D objects, and trenches, which are useful components of photonic devices, microfluidic devices, bio-medical devices, batteries, Vias, MEMS, X-ray optics, etc. With no limitations of large-areas and low-cost processing, MacEtch can open up new opportunities for several applications where high precision nano- and microfabrication is required. This can make semiconductor manufacturing more accessible to researchers in various fields, and accelerate innovation in electronics, bio-medical engineering, energy, and photonics. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on novel methodological developments in MacEtch, and its use for various applications.

Download or read book Integrated Fabrication of Micro and Nano scale Structures for Silicon Devices Enabled by Metal assisted Chemical Etch written by Raul Marcel Lema Galindo and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon device manufacturing, at both the micro and nanoscales, is largely performed using plasma etching techniques such as Reactive Ion Etching. Deep Reactive Ion Etching (DRIE) can be used to create high-aspect ratio nanostructures in silicon. The DRIE process suffers from low throughput, only one wafer can be processed at a time; high cost, the necessary tools and facilities for implementation are expensive; and surface defects such as sidewall taper and scalloping as a consequence of the cycling process required for high-aspect-ratio manufacturing. A potential solution to these issues consists of implementing wet-etching techniques, which do not require expensive equipment and can be implemented at a batch scale. Metal Assisted Chemical Etch is a wet-etch process that uses a metal catalyst to mediate silicon oxidation and removal in a diffusion-based process. This process has been demonstrated to work for both micro and nanoscale feature manufacturing on silicon substrates. To date, however, a single study aimed at identifying experimental conditions for successful multi-scale (integrated micro- and nanoscale) manufacturing is lacking in the literature. This mixed micro-nanoscale etching process (IMN-MACE) can enable a wide variety of applications including, for example, development of point-of-care medical diagnostic devices which rely on micro- and nano-fluidic sample processing, a growing field in the area of preventive medicine. This work developed multi-scale MACE by a systematic experimental exploration of the process space. A total of 54 experiments were performed to study the effects of the following process parameters: (i) surface silicon dioxide, (ii) metal catalyst stack, (iii) etchant solution concentration, and (iv) pre-etch sample preparation. Of these 54 experiments, 18 experiments were based on exploring nanopatterning of 100nm pillars, and the remaining 36 explored the fabrication of micropillars with a diameter between 10μm and 50μm in 5μm increments. It was determined that a single catalyst stack consisting of ~3nm Ag underneath a ~15nm Au metal layer can be used to etch high quality features at both the micro and nanoscales on a silicon substrate pre-treated with hydrogen fluoride to remove the native oxide layer from the surface. Future steps for micro-nano scale integration were also proposed

Download or read book Fabrication of High Aspect Ratio Silicon Nanostructure Arrays by Metal assisted Etching written by Shih-wei Chang (Ph.D.) and published by . This book was released on 2010 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research was to explore and understand the mechanisms involved in the fabrication of silicon nanostructures using metal-assisted etching. We developed a method utilizing metal-assisted etching in conjunction with block copolymer lithography to create ordered and densely-packed arrays of high-aspect-ratio single-crystal silicon nanowires with uniform crystallographic orientations. Nanowires with sub-20 nm diameters were created as either continuous carpets or as carpets within trenches. Wires with aspect ratios up to 220 with much reduced capillary-induced clustering were achieved through post-etching critical point drying. The size distribution of the diameters was narrow and closely followed the size distribution of the block copolymer. Fabrication of wires in topographic features demonstrated the ability to accurately control wire placement. The flexibility of this method will facilitate the use of such wire arrays in micro- and nano-systems in which high device densities and/or high surface areas are desired. In addition, we report a systematic study of metal-catalyzed etching of (100), (110), and (111) silicon substrates using gold catalysts with varying geometrical characteristics. It is shown that for isolated catalyst nanoparticles and metal meshes with small hole spacings, etching proceeded preferentially in the 100 direction. However, etching was confined in the direction vertical to the substrate surface when a catalyst mesh with large hole spacings was used. This result was used to demonstrate the use of metal-assisted etching to create arrays of vertically-aligned polycrystalline and amorphous silicon nanowires etched from deposited silicon thin films using catalyst meshes with relatively large hole spacings. The ability to pattern wires from polycrystalline and amorphous silicon thin films opens the possibility of making silicon nanowire-array-based devices on a much wider range of substrates. Finally, we demonstrated the fabrication of a silicon-nanopillar-based nanocapacitor array using metal-assisted etching and electrodeposition. The capacitance density was increased significantly as a result of an increased electrode area made possible by the catalytic etching approach. We also showed that the measured capacitance densities closely follow the expected trend as a function of pillar height and array period. The capacitance densities can be further enhanced by increasing the array density and wire length with the incorporation of known self-assembly-based patterning techniques such as block copolymer lithography.

Download or read book Thin Silicon and Metal assisted Chemical Etching for Photovoltaic and Electronic Devices written by Ruby A. Lai and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrathin silicon membranes, less than 20um thick, have extreme flexibility, lightness, and the superior materials quality and advantages in silicon micro-processing. There are two major roadblocks in developing ultrathin silicon membranes: the fabrication processing of the more delicate material in traditional CMOS fabrication, and the manufacturing of high quality, ultrathin sheets from bulk Si material. First, I use alkaline silicon etching of silicon wafers to form ultrathin silicon sheets, supported by a thick ring of Si material on its edge, that enable facile processing of large 3" sheets in traditional CMOS apparatuses. Second, I explored the novel use of a "chemical wafer-saw" for silicon by using metal-assisted chemical etching, as a possible pathway to create thin silicon sheets. Third, I developed a new theoretical model for the mechanism of metal-assisted chemical etching of silicon, which explained for the first time the silicon doping dependence of the etch. Fourth, I present computational design and fabrication of a novel nanophotonic solar cell contact for a metal-insulator-semiconductor solar cell, as well as other nanostructures, fabricated using metal-assisted chemical etching.

Download or read book Nonlithographic Manufacturing of 1 D Silicon Nanostructures with Tunable Surface Morphology Via Thermal Dewetting and Metal assisted Chemical Etching written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reaction Control of Metal assisted Chemical Etching for Silicon based Zone Plate Nanostructures written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Thermal Oxide Film on Scalable Fabrication of Silicon Nanowire Arrays Using Metal Assisted Chemical Etching written by Mariana Castaneda and published by . This book was released on 2020 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last several decades, the demand for real-time data processing and storage has exponentially increased and pushed the semiconductor field to its fabrication limits. Traditional methods of semiconductor nanomanufacturing, like lithography and reactive ion etching (RIE), suffer from feature resolution and etch taper limits for devices comprising sub-10 nm nanofabrication nodes. Methods like the ones mentioned above are both expensive and difficult to manufacture to keep up with continued scaling requirements of semiconductor fabrication. This thesis presents a fabrication method and metrology characterization of silicon nanowire arrays using a Metal Assisted Chemical Etching (MACE) approach. MACE is a simple, low-cost fabrication technique that allows for high aspect ratio silicon nanostructures to be successfully fabricated without sacrificing geometry fidelity, making it a promising etching method for large-scale semiconductor manufacturing. In this research, small-scale MACE was demonstrated on silicon coupons with an initial process window of 0 nm - 100 nm oxide thickness. Then, a down-selected process window of 10 nm - 50 nm oxide thickness was successfully reproduced on a full-wafer scale (100 mm diameter silicon wafers) at different etchant solution concentrations. The oxide layer serves as a sacrificial layer between the silicon and resist to allow a consistent etching starting point, thus improving the etch depth uniformity and aspect ratios of silicon nanowires. The silicon nanowires were characterized using local scanning electron microscopy (SEM) images by mapping the areas of the wafer as North, South, East, and West to measure critical dimensions such as height and diameter, as well as to observe phenomena such as nanowire collapse

Download or read book Metal assisted Chemical Etching of Semiconductor Nanostructures for Electronic Applications written by Jeong Dong Kim and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Semiconductor Nanofabrication Via Metal assisted Chemical Etching written by Thomas S. Wilhelm and published by . This book was released on 2019 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The increasing demand for complex devices that utilize three-dimensional nanostructures has incentivized the development of adaptable and versatile semiconductor nanofabrication strategies. Without the introduction and refinement of methodologies to overcome traditional processing constraints, nanofabrication sequences risk becoming obstacles that impede device evolution. Crystallographic wet-chemical etching (e.g., Si in KOH) has historically been sufficient to produce textured Si surfaces with smooth sidewalls, though it lacks the ability to yield high aspect-ratio features. Physical and chemical plasma etching (e.g., reactive-ion etching) evolved to allow for the creation of vertical structures within integrated circuits; however, the high energy ion bombardment associated with dry etching can cause lattice and sidewall damage that is detrimental to device performance, particularly as structures progress within the micro- and nano-scale regimes. Metal-assisted chemical etching (MacEtch) provides an alternative processing scheme that is both solution-based and highly anisotropic. This fabrication method relies on a suitable catalyst (e.g., Au, Ag, Pt, or Pd) to induce semiconductor etching in a solution containing an oxidant and an etchant. The etching would otherwise be inert without the presence of the catalyst. The MacEtch process is modelled after a galvanic cell, with cathodic and anodic half reactions occurring at the solution/catalyst and catalyst/semiconductor interfaces, respectively. The metal catalyzes the reduction of oxidant species at the cathode, thereby generating charge carriers (i.e., holes) that are locally injected into the semiconductor at the anode. The solution interacts with the ionized substrate, which creates an oxide that is preferentially attacked by the etchant. Thus, MacEtch offers a nanofabrication alternative that combines the advantages of both wet- and dry-etching, while also overcoming many of their accompanying limitations. This provides a tunable semiconductor processing platform using controlled top-down catalytic etching, affording engineers greater processing control and versatility over conventional methodologies. Here, Au-enhanced MacEtch of the ternary alloys InGaP and AlGaAs is demonstrated for the first time, and processes are detailed for the formation of suspended III-V nanofoils and ordered nanopillar arrays. Next, a lithography-free and entirely solution-based method is outlined for the fabrication of black GaAs with solar-weighted reflectance of ~4%. Finally, a comparison between Au- and CNT-enhanced Si MacEtch is presented towards CMOS-compatibility using catalysts that do not introduce deep level traps. Sample preparation and etching conditions are shown to be adaptable to yield an a priori structural design, through a modification of injected hole distributions. Critical process parameters that guide the MacEtch mechanisms are considered at length, including heteroepitaxial effects, ternary material composition, etching temperature, and catalyst type, size, and deposition technique. This work extends the range of MacEtch materials and its fundamental mechanics for fabrication of micro- and nano-structures with applications in optoelectronics, photovoltaics, and nanoelectronics."--Abstract.

Download or read book Integrated Silicon Metal Systems at the Nanoscale written by Munir H. Nayfeh and published by Elsevier. This book was released on 2023-04-12 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Integrated Silicon-Metal Systems at the Nanoscale: Applications in Photonics, Quantum Computing, Networking, and Internet is a comprehensive guide to the interaction, materials and functional integration at the nanoscale of the silicon-metal binary system and a variety of emerging and next-generation advanced device applications, from energy and electronics, to sensing, quantum computing and quantum internet networks. The book guides the readers through advanced techniques and etching processes, combining underlying principles, materials science, design, and operation of metal-Si nanodevices. Each chapter focuses on a specific use of integrated metal-silicon nanostructures, including storage and resistive next-generation nano memory and transistors, photo and molecular sensing, harvest and storage device electrodes, phosphor light converters, and hydrogen fuel cells, as well as future application areas, such as spin transistors, quantum computing, hybrid quantum devices, and quantum engineering, networking, and internet. Provides detailed coverage of materials, design and operation of metal-Si nanodevices Offers a step-by-step approach, supported by principles, methods, illustrations and equations Explores a range of cutting-edge emerging applications across electronics, sensing and quantum computing

Download or read book Resolution Limits of Metal Assisted Chemical Etching of Polysilicon written by Crystal Barrera and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Patterning and etching high aspect ratio, sub-50 nanometer structures for 3D device architectures is becoming a critical challenge in advanced semiconductor device fabrication. Metal assisted chemical etching (MACE) is a wet etch process that has demonstrated very high aspect ratio structures in single crystal silicon at sub-50 nanometer scale. The capabilities of this process can be applied to etching of gate structures made in bulk or epitaxially grown single crystal silicon, however, it is important to extend MACE to other materials for a range of semiconductor device architectures. In this research, we build on preliminary results published in the literature showing MACE for polycrystalline silicon. If it can be demonstrated that MACE of polysilicon can retain the sub-50 nanometer resolution and high aspect ratio produced with MACE of single crystal silicon, process techniques can be developed around polysilicon MACE to fabricate critical structures needed in advanced Dynamic RAM, 3D Flash and vias for logic devices. It is also important to demonstrate that atomically precise side walls that are near-perfect in maintaining 90-degree wall angle, as demonstrated with MACE applied to single crystal silicon, can also be achieved in polycrystalline silicon. Metal assisted chemical etching (MACE) is a promising approach that addresses many issues that arise from underperforming reactive ion etching (RIE) methods that have limitations in fabricating high aspect ratio sub-50 nanometer nanostructures due to presence of tapered profiles and high side wall roughness. However, MACE is extremely limited in the types of materials for which it has been demonstrated. MACE has shown reliable etching only in single crystal silicon which limits its applications to a small number of front-end semiconductor device layers. This work extends the capabilities of MACE to polysilicon which when combined with additional process steps has the potential to create patterns for metal vias and deep trench capacitors, both of which are important in the semiconductor industry. Much of the existing literature on MACE for polysilicon builds an underlying hypothesis; etch quality of polysilicon is compromised by the inherent crystalline structure of the material. There is an especial lack in understanding how MACE works at crystal grain boundaries, which presents risk in reduced atomic precision due to sidewall roughness induced by these boundaries –limiting the value of MACE for sub-50 nanometer structures. In this work, we present a MACE wet etch of polysilicon that produces structure arrays with sub-50nm resolution and anisotropic profile. The three demonstrated structures are pillars of 6:1 aspect ratio and 50nm spacing for comparison to MACE literature, pillars of 30nm spacing to establish resolution limitations of polysilicon etch, and a diamond pillar array with potential to fabricate holes with as low as 15nm spacing

Download or read book Sustainable Routes to Porous Silicon Nanostructures as Drug and Gene Delivery Vehicles written by Jhansi Rani Kalluri and published by . This book was released on 2018 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porous silicon (pSi), with its nanoscale architecture, acts as a promising resorbable biomaterial for a broad variety of applications: biosensors, orthopedic tissue engineering, and controlled drug delivery. The most conventional methods for preparing porous silicon particles are anodization of silicon wafers and metal-assisted chemical etching (MACE). These established techniques require elemental crystalline silicon feedstocks, and the use of corrosive hydrofluoric acid (HF) and organic solvents. Rather than employing these methods, we have developed an eco-friendly alternative of producing pSi from silicon accumulator plants/agriculture waste. Two different silicon accumulator plants Bambuseae (tabasheer) and Equisetum telmateia (great horsetail)have been investigated for this purpose, and high surface area porous silicon nanostructures prepared using a magnesiothermic reduction of silica isolated from these plants. This fabrication process of pSi includes extraction of biogenic silica from the ground plant by calcination, followed by reduction with magnesium, and purification of reduced Si product. Details of fabrication process and characterization of pSi powders by a combination of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), and low temperature nitrogen gas adsorption measurements will be outlined in this presentation. As pointed out above, Bambuseae serves as a viable eco-friendly starting materials for fabricating porous silicon (pSi).At the same time, if the selected plant leaf components contain medicinally-active species (antibacterial) as well, then the single substance can provide not only the nanoscale high surface area drug delivery carrier, but the drug itself. With this idea in mind using a single plant source (Bambuseae) we have developed porous silicon based drug delivery carrier matrix for the sustained release of antibacterials. Nanoentrapment of vitamins, nutrients, and plant based therapeutics is another attractive area in food and pharmaceutical industries to address the challenges of stability and bioavailability of entrapped agents. One way to increase the bioavailability of the drugs is by enhancing their solubility. We have evaluated the ability of nanostructured plant-derived porous silicon particles (pSi) as potential candidates to increase the solubility of plant extracts rich in therapeutic polyphenolic compounds (Equisetum arvense) and a poorly water soluble vitamin (vitamin d3). We have also evaluated the ability of plant derived porous silicon nanoparticles (pSiNPs) as gene delivery vehicles. Following necessary reduction of pSiNP particle size and functionalization with primary amine moieties at the nanoparticle surface, the binding of a reporter plasmid DNA, pEF1-eGFP (endothelial factor 1 enhanced green fluorescent protein, 6429 bp) to the pSiNPs was investigated, followed by attempted transfection of HEK293 cells.

Download or read book Fabrication of Silicon Nanowires with Controlled Nano scale Shapes Using Wet Anisotropic Etching written by Bailey Anderson Yin and published by . This book was released on 2015 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon nanowires can enable important applications in energy and healthcare such as biochemical sensors, thermoelectric devices, and ultra-capacitors. In the energy sector, for example, as the need for more efficient energy storage continues to grow for enabling applications such as electric vehicles, high energy storage density capacitors are being explored as a potential replacement to traditional batteries that lack fast charge/discharge rates as well as have shorter life cycles. Silicon nanowire based ultra-capacitors offer increased energy storage density by increasing the surface area per unit projected area of the electrode, thereby allowing more surface “charge” to reside. The motivation behind this dissertation is the study of low-cost techniques for fabrication of high aspect ratio silicon nanowires with controlled geometry with an exemplar application in ultra-capacitors. Controlled transfer of high aspect ratio, nano-scale features into functional device layers requires anisotropic etch techniques. Dry reactive ion etch techniques are commonly used since most solution-based wet etch processes lack anisotropic pattern transfer capability. However, in silicon, anisotropic wet etch processes are available for the fabrication of nano-scale features, but have some constraints in the range of geometry of patterns that they can address. While this lack of geometric and material versatility precludes the use of these processes in applications like integrated circuits, they can be potentially realized for fabricating nanoscale pillars. This dissertation explores the geometric limitations of such inexpensive wet anisotropic etching processes and develops additional methods and geometries for fabrication of controlled nano-scale, high aspect ratio features. Jet and Flash Imprint Lithography (J-FILTM) has been used as the preferred pre-etch patterning process as it enables patterning of sub-50 nm high density features with versatile geometries over large areas. Exemplary anisotropic wet etch processes studied include Crystalline Orientation Dependent Etch (CODE) using potassium hydroxide (KOH) etching of silicon and Metal Assisted Chemical Etching (MACE) using gold as a catalyst to etch silicon. Experiments with CODE indicate that the geometric limitations of the etch process prevent the fabrication of high aspect ratio nanowires without adding a prohibitive number of steps to protect the pillar geometry. On the other hand, MACE offers a relatively simple process for fabricating high aspect ratio pillars with unique cross sections, and has thus been pursued to fabricate fully functional electrostatic capacitors featuring both circular and diamond-shaped nano-pillar electrodes. The capacitance of the diamond-shaped nano-pillar capacitor has been shown to be ~77.9% larger than that of the circular cross section due to the increase in surface area per unit projected area. This increase in capacitance approximately matches the increase calculated using analytical models. Thus, this dissertation provides a framework for the ability to create unique sharp cornered nanowires that can be explored further for a wider variety of cross sections.

Download or read book Metal Assisted Chemical Etching of Silicon and Other Semiconductors written by O. Hildreth and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: