This study was supported by the United States (US) Department of Veterans Affairs Rehabilitation Research and Development Service awards: #RX001664-01A1 (CDA-1, Ereifej) and #RX002628-01A1 (CDA-2, Ereifej). The contents do not represent the views of the U.S. Department of Veterans Affairs or the United States Government. The authors would like to thank FEI Co. (Now part of Thermofisher Scientific) for staff assistance and use of instrumentation, which aided in developing the scripts used in this research.

The authors have nothing to disclose.

The fabrication protocol outlined here utilizes focused ion beam lithography to effectively and reproducibly etch nano-architectures into the surface of non-functional and functional single shank silicon microelectrodes. Focused ion beam (FIB) lithography allows for the selective ablation of the substrate surface by using a finely-focused ion beam50,51. FIB is a direct-write technique that can produce various features with nanoscale resolution and high aspect rat...

Intracortical Microelectrodes (IME) are invasive electrodes which provide a means of direct interfacing between external devices and the neuronal populations inside the cerebral cortex1,2. This technology is an invaluable tool for recording neural action potentials to improve scientists&#39; ability to explore neuronal function, advance understanding of neurological diseases and develop potential therapies. Intracortical microelectrode, used as a part of Brain Machine Interface (BMI) systems, enables recording of action potentials from an individual or small groups of neurons to detect motor intentions that can be used to produce functional outputs3. In fact, BMI systems have successfully been used for prosthetic and therapeutic purposes, such as acquired sensorimotor rhythm control to operate a computer cursor in patients with amyotrophic lateral sclerosis (ALS)4 and spinal cord injuries5 and restoring the movement in people suffering from chronic tetraplegia6.
Unfortunately, IMEs often fail to record consistently over time due to several failure modes that include mechanical, biological and material factors7,8. The neuroinflammatory response occurring after the electrode implantation is thought to be a considerable challenge contributing to electrode failure9,10,11,12,13,14. The neuroinflammatory response is initiated during the initial insertion of the IME which severs the blood brain barrier, damages the local brain parenchyma and disrupts glial and neuronal networks15,16. This acute response is characterized by the activation of glial cells (microglia/macrophages and astrocytes), which release pro-inflammatory and neurotoxic molecules around the implant site17,18,19,20. The chronic activation of glial cells results in a foreign body reaction characterized by the formation of a glial scar isolating the electrode from healthy brain tissue7,9,12,13,17,21,22. Ultimately, hindering the electrode&#39;s ability to record neuronal action potentials, due to the physical barrier between the electrode and the neurons and the degeneration and death of neurons23,24,25.
The early failure of intracortical microelectrodes has brought about considerable research in the development of next generation electrodes, with emphasis on biomimetic strategies26,27,28,29,30. Of particular interest to the protocol described here, is the use of nano-architecture as a class of biomimetic surface alterations for IMEs31. It has been established that surfaces mimicking the architecture of the natural in vivo environment have an improved biocompatible response32,33,34,35,36. Thus, the hypothesis compelling this protocol is that the discontinuity between the rough architecture of the brain tissue and smooth architecture of the intracortical microelectrodes may contribute to the neuroinflammatory and chronic foreign body response to implanted IMEs (for a full review refer to Kim et al.31). We have previously shown that the utilization of nano-architecture features similar to the brain&#39;s extracellular matrix architecture reduces astrocyte inflammatory markers from cells cultured on nano-architectured substrates, compared to flat control surfaces in both in vitro and ex vivo models of neuroinflammation37,38. Furthermore, we have shown the application of focused ion beam (FIB) lithography to etch nano-architectures directly onto silicon probes resulted in significantly increased neuronal viability and lower expression of pro-inflammatory genes from animals implanted with the nano-architecture probes compared to the smooth control group26. Therefore, the purpose of the protocol presented here is to describe the use of FIB lithography to etch nano-architectures on manufactured intracortical microelectrode devices. This protocol was designed to etch nano-architecture sized features into silicon surfaces of intracortical microelectrode shanks utilizing both automated and manual processes. These methods are uncomplicated, reproducible, and can certainly be optimized for various device materials and desired feature sizes.

<table><tbody><tr><td>16-Channel ZIF-Clip Headstage</td><td>Tucker Davis Technologies</td><td>ZC16</td><td>The headstage and headstage holder may need to be changed, depending on the electrode used. &lt;a href=&quot;https://www.tdt.com/zif-clip-digital-headstages.html&quot; target=&quot;_blank&quot;&gt;https://www.tdt.com/zif-clip-digital-headstages.html&lt;/a&gt;</td></tr><tr><td>1-meter cable, ALL spring wrapped</td><td>Thomas Scientific</td><td>1213F04</td><td>Any non treated petri dish will suffice. &lt;a href=&quot;https://www.thomassci.com/Laboratory-Supplies/Cell-Culture-Dishes/_/Non-Treated-Petri-Dishes?q=petri%20dish%20cell%20culture&quot; target=&quot;_blank&quot;&gt;https://www.thomassci.com/Laboratory-Supplies/Cell-Culture-Dishes/_/Non-Treated-Petri-Dishes?q=petri%20dish%20cell%20culture&lt;/a&gt;</td></tr><tr><td>32-Channel ZIF-Clip Headstage Holder</td><td>Tucker Davis Technologies</td><td>Z-ROD32</td><td>The headstage and headstage holder may need to be changed, depending on the electrode used. &lt;a href=&quot;https://www.tdt.com/zif-clip-digital-headstages.html&quot; target=&quot;_blank&quot;&gt;https://www.tdt.com/zif-clip-digital-headstages.html&lt;/a&gt;</td></tr><tr><td>Acetone, Thinner/Extender/Cleaner, 30ml</td><td>Ted Pella</td><td>16023</td><td>&lt;a href=&quot;https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062&quot; target=&quot;_blank&quot;&gt;https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062&lt;/a&gt;</td></tr><tr><td>Baby-Mixter Hemostat</td><td>Fine Science Tools</td><td>13013-14</td><td>Any curved hemostat will suffice. &lt;a href=&quot;https://www.finescience.com/en-US/Products/Forceps-Hemostats/Hemostats/Baby-Mixter-Hemostat&quot; target=&quot;_blank&quot;&gt;https://www.finescience.com/en-US/Products/Forceps-Hemostats/Hemostats/Baby-Mixter-Hemostat&lt;/a&gt;</td></tr><tr><td>Carbon Conductive Tape, Double Coated</td><td>Ted Pella</td><td>16084-7</td><td>The protocol suggested three options for mounting the functional electrode to the aluminum stub (copper or carbon conductive tape or a low profile clip. We utilized the carbon conductive tape in our study. &lt;a href=&quot;https://www.tedpella.com/semmisc_html/semadhes.htm&quot; target=&quot;_blank&quot;&gt;https://www.tedpella.com/semmisc_html/semadhes.htm&lt;/a&gt;</td></tr><tr><td>Corning Costar Not Treated Multiple Well Plates - 6 well</td><td>Sigma Aldrich</td><td>CLS3736-100EA</td><td>Any non-treated 6 well plate will suffice. &lt;a href=&quot;https://www.sigmaaldrich.com/catalog/substance/corningcostarnottreatedmultiplewellplates1234598765&quot; target=&quot;_blank&quot;&gt;https://www.sigmaaldrich.com/catalog/substance/&lt;/a&gt;</td></tr><tr><td>Dumont #5 Fine Forceps</td><td>Fine Science Tools</td><td>11251-30</td><td>Either this fine forceps or the vacuum pump will suffice. &lt;a href=&quot;https://www.finescience.com/en-US/Products/Forceps-Hemostats/Dumont-Forceps/Dumont-5-Forceps/11251-30&quot; target=&quot;_blank&quot;&gt;https://www.finescience.com/en-US/Products/Forceps-Hemostats/Dumont-Forceps/Dumont-5-Forceps/11251-30&lt;/a&gt;</td></tr><tr><td>Ethanol, 190 proof (95%), USP, Decon Labs</td><td>Fisher Scientific</td><td>22-032-600</td><td>Any 95% ethanol will suffice. &lt;a href=&quot;https://www.fishersci.com/shop/products/ethanol-190-proof-95-usp-decon-labs-10/22032600&quot; target=&quot;_blank&quot;&gt;https://www.fishersci.com/shop/products/ethanol-190-proof-95-usp-decon-labs-10/22032600&lt;/a&gt;</td></tr><tr><td>Falcon Cell Strainer</td><td>Fisher Scientific</td><td>08-771-1</td><td>&lt;a href=&quot;https://www.fishersci.com/shop/products/falcon-cell-strainers-4/087711&quot; target=&quot;_blank&quot;&gt;https://www.fishersci.com/shop/products/falcon-cell-strainers-4/087711&lt;/a&gt;</td></tr><tr><td>FEI, Tescan, Zeiss (also for Philips, Leo, Cambridge, Leica, CamScan), aluminum, grooved edge, &amp;Oslash;32mm</td><td>Ted Pella</td><td>16148</td><td>Depending on the SEM machine used, you may need a different size stub. &lt;a href=&quot;https://www.tedpella.com/SEM_html/SEMpinmount.htm#_16180&quot; target=&quot;_blank&quot;&gt;https://www.tedpella.com/SEM_html/SEMpinmount.htm#_16180&lt;/a&gt;</td></tr><tr><td>Fisherbrand Aluminum Foil, Standard-gauge roll</td><td>Fisher Scientific</td><td>01-213-101</td><td>Any aluminum foil will suffice. &lt;a href=&quot;https://www.fishersci.com/shop/products/fisherbrand-aluminum-foil-7/p-306250&quot; target=&quot;_blank&quot;&gt;https://www.fishersci.com/shop/products/fisherbrand-aluminum-foil-7/p-306250&lt;/a&gt;</td></tr><tr><td>Fisherbrand Low- and Tall-Form PTFE Evaporating Dishes</td><td>Fisher Scientific</td><td>02-617-149</td><td>Any Teflon plate will suffice, this is used to dry the probes after washing on a surface they will not stick onto. &lt;a href=&quot;https://www.fishersci.com/shop/products/fisherbrand-low-tall-form-ptfe-evaporating-dishes-12/p-88552&quot; target=&quot;_blank&quot;&gt;https://www.fishersci.com/shop/products/fisherbrand-low-tall-form-ptfe-evaporating-dishes-12/p-88552&lt;/a&gt;</td></tr><tr><td>Michigan-style silicon functional electrode</td><td>NeuroNexus</td><td>A1x16-3mm-100-177</td><td>&lt;a href=&quot;http://neuronexus.com/electrode-array/a1x16-3mm-100-177/&quot; target=&quot;_blank&quot;&gt;http://neuronexus.com/electrode-array/a1x16-3mm-100-177/&lt;/a&gt;</td></tr><tr><td>Model 1772 Universal holder</td><td>KOPF</td><td>Model 1772</td><td>Other stereotaxic frames and accessories will suffice. &lt;a href=&quot;http://kopfinstruments.com/product/model-1772-universal-holder/&quot; target=&quot;_blank&quot;&gt;http://kopfinstruments.com/product/model-1772-universal-holder/&lt;/a&gt;</td></tr><tr><td>Model 900-U Small Animal Stereotaxic Instrument</td><td>KOPF</td><td>Model 900-U</td><td>Other stereotaxic frames and accessories will suffice. &lt;a href=&quot;http://kopfinstruments.com/product/model-900-small-animal-stereotaxic-instrument1/&quot; target=&quot;_blank&quot;&gt;http://kopfinstruments.com/product/model-900-small-animal-stereotaxic-instrument1/&lt;/a&gt;</td></tr><tr><td>Model 960 Electrode Manipulator with AP Slide Assembly</td><td>KOPF</td><td>Model 960</td><td>Other stereotaxic frames and accessories will suffice. &lt;a href=&quot;http://kopfinstruments.com/product/model-1772-universal-holder/&quot; target=&quot;_blank&quot;&gt;http://kopfinstruments.com/product/model-1772-universal-holder/&lt;/a&gt;</td></tr><tr><td>Parafilm M 10cm x 76.2m (4&quot; x 250&#039;)</td><td>Ted Pella</td><td>807-5</td><td>&lt;a href=&quot;https://www.tedpella.com/grids_html/807-2.htm&quot; target=&quot;_blank&quot;&gt;https://www.tedpella.com/grids_html/807-2.htm&lt;/a&gt;</td></tr><tr><td>PELCO Vacuum Pick-Up System, 220V</td><td>Ted Pella</td><td>520-1-220</td><td>Either this vacuum pump or the fine forceps will suffice. &lt;a href=&quot;http://www.tedpella.com/grids_html/Vacuum-Pick-Up-Systems.htm#anchor-520&quot; target=&quot;_blank&quot;&gt;http://www.tedpella.com/grids_html/Vacuum-Pick-Up-Systems.htm#anchor-520&lt;/a&gt;</td></tr><tr><td>PELCO Conductive Silver Paint</td><td>Ted Pella</td><td>16062</td><td>&lt;a href=&quot;https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062&quot; target=&quot;_blank&quot;&gt;https://www.tedpella.com/SEMmisc_html/SEMpaint.htm#anchor16062&lt;/a&gt;</td></tr><tr><td>SEM FIB FEI Helios 650 Nanolab</td><td>Thermo Fisher Scientific</td><td>Helios G2 650</td><td>This is the specific focused ion beam and scanning electron microscope used in the protocol. The Nanobuilder software is what it comes with. If a different FIB instrument is used, it may not be completely compatible with the protocol, specifically the steps requiring the Nanobuilder software. &lt;a href=&quot;https://www.fei.com/products/dualbeam/helios-nanolab/&quot; target=&quot;_blank&quot;&gt;https://www.fei.com/products/dualbeam/helios-nanolab/&lt;/a&gt;</td></tr></tbody></table>

focused ion beam lithography to etch nano-architectures into microelectrodes

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of sophisticated microelectrodes with greater resolution and expanded capabilities. The progress in fabrication technology has supported the development of biomimetic electrodes, which aim to seamlessly integrate into the brain parenchyma, reduce the neuroinflammatory response observed after electrode insertion and improve the quality and longevity of electrophysiological recordings. Here we describe a protocol to employ a biomimetic approach recently classified as nano-architecture. The use of focused ion beam lithography (FIB) was utilized in this protocol to etch specific nano-architecture features into the surface of non-functional and functional single shank intracortical microelectrodes. Etching nano-architectures into the electrode surface indicated possible improvements of biocompatibility and functionality of the implanted device. One of the benefits of using FIB is the ability to etch on manufactured devices, as opposed to during the fabrication of the device, facilitating boundless possibilities to modify numerous medical devices post-manufacturing. The protocol presented herein can be optimized for various material types, nano-architecture features, and types of devices. Augmenting the surface of implanted medical devices can improve the device performance and integration into the tissue.

FIB Etched Nano-architecture on the Surfaces of Single Shank Intracortical Probes 
Utilizing the methods described here, intracortical probes were etched with specific nano-architectures following established protocols39. Dimensions and shape of the nano-architecture design described in these methods were implemented from previous in vitro results depicting a decrease in glial cell reactivity when cultured with the nano-architecture design described here37</...

Watch this Scientific Journal Video about Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes at JoVE.com

Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

We have shown that the etching of nano-architecture into intracortical microelectrode devices may reduce the inflammatory response and has the potential to improve electrophysiological recordings. The methods described herein outline an approach to etch nano-architectures into the surface of non-functional and functional single shank silicon intracortical microelectrodes.

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of ...

focused-ion-beam-lithography-to-etch-nano-architectures-into

Research

JoVE Journal

Bioengineering

6.7K Views.  University of Michigan. Het gebruik van gerichte ionenbundel lithografie, of FIB, stelt onderzoekers in staat om de interactie tussen het celoppervlak te verbeteren door materiaaloppervlakken te ontwerpen die de biocompatibiliteit en integratie met het inheemse weefsel hebben verhoogd. Met FIB kunnen functies worden geëtst op een verscheidenheid aan materialen, zoals silicium, metalen en polymeren. Niet-vlakke oppervlakken kunnen ook worden gebruikt en nabewerking kan worden uitgevoerd op individuele apparaten....

Video: Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Engineering

Atomically Traceable Nanostructure Fabrication

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

We report a protocol for combining the atomic metrology of the Scanning Tunneling Microscope for surface patterning with selective Atomic Layer Deposition and Reactive Ion Etching. Using a robust process involving numerous atmospheric exposures and transport, 3D nanostructures with atomic metrology are fabricated.

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process ...

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal&#8211;semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 &#937;&#8722;1 cm&#8722;1, with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

We describe the approaches for the device fabrication and electrical characterization of molybdenum diselenide (MoSe2) layer semiconductor nanostructures with different thicknesses. In addition, the fabrication of ohmic contacts for MoSe2-layer nanocrystals by the focused-ion beam deposition method using platinum (Pt) as a contact metal is described.

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor ...

Microfabrication of Chip-sized Scaffolds for Three-dimensional Cell cultivation

Using microfabrication technologies is a prerequisite to create scaffolds of reproducible geometry and constant quality for three-dimensional cell cultivation. These technologies offer a wide spectrum of advantages not only for manufacturing but also for different applications. The size and shape of formed cell clusters can be influenced by the exact and reproducible architecture of the microfabricated scaffold and, therefore, the diffusion path length of nutrients and gases can be controlled.1 This is unquestionably a useful tool to prevent apoptosis and necrosis of cells due to an insufficient nutrient and gas supply or removal of cellular metabolites.
Our polymer chip, called CellChip, has the outer dimensions of 2 x 2 cm with a central microstructured area. This area is subdivided into an array of up to 1156 microcontainers with a typical dimension of 300 m edge length for the cubic design (cp- or cf-chip) or of 300 m diameter and depth for the round design (r-chip).2
So far, hot embossing or micro injection moulding (in combination with subsequent laborious machining of the parts) was used for the fabrication of the microstructured chips. Basically, micro injection moulding is one of the only polymer based replication techniques that, up to now, is capable for mass production of polymer microstructures.3 However, both techniques have certain unwanted limitations due to the processing of a viscous polymer melt with the generation of very thin walls or integrated through holes. In case of the CellChip, thin bottom layers are necessary to perforate the polymer and provide small pores of defined size to supply cells with culture medium e.g. by microfluidic perfusion of the containers.
In order to overcome these limitations and to reduce the manufacturing costs we have developed a new microtechnical approach on the basis of a down-scaled thermoforming process. For the manufacturing of highly porous and thin walled polymer chips, we use a combination of heavy ion irradiation, microthermoforming and track etching. In this so called "SMART" process (Substrate Modification And Replication by Thermoforming) thin polymer films are irradiated with energetic heavy projectiles of several hundred MeV introducing so-called "latent tracks" Subsequently, the film in a rubber elastic state is formed into three dimensional parts without modifying or annealing the tracks. After the forming process, selective chemical etching finally converts the tracks into cylindrical pores of adjustable diameter.

We present two processes for the microfabrication of porous polymer chips for three-dimensional cell cultivation. The first one is hot embossing combined with a solvent vapour welding process. The second one uses a recently developed microthermoforming process combined with ion track technology leading to a significant simplification of manufacture.

Using microfabrication technologies is a prerequisite to create scaffolds of reproducible geometry and constant quality for three-dimensional cell ...

Biology

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has been attributed to statistical fluctuations in the number of photons/electrons arriving at a given nano-region arising from shot-noise (SN). The SN varies inversely to the square root of a number of photons/electrons. For a fixed dosage, the SN is larger in EUV and E-beam lithographies than for traditional (193 nm) optical lithography. Bottom-up and top-down patterning approaches are combined to minimize the effects of shot noise in nano-hole patterning. Specifically, an amino-silane surfactant self-assembles on a silicon wafer that is subsequently spin-coated with a 100 nm film of a PMMA-based E-beam photoresist. Exposure to the E-beam and the subsequent development uncover the underlying surfactant film at the bottoms of the holes. Dipping the wafer in a suspension of negatively charged, citrate-capped, 20 nm gold nanoparticles (GNP) deposits one particle per hole. The exposed positively charged surfactant film in the hole electrostatically funnels the negatively charged nanoparticle to the center of an exposed hole, which permanently fixes the positional registry. Next, by heating near the glass transition temperature of the photoresist polymer, the photoresist film reflows and engulfs the nanoparticles. This process erases the holes affected by SN but leaves the deposited GNPs locked in place by strong electrostatic binding. Treatment with oxygen plasma exposes the GNPs by etching a thin layer of the photoresist. Wet-etching the exposed GNPs with a solution of I2/KI yields uniform holes located at the center of indentations patterned by E-beam lithography. The experiments presented show that the approach reduces the variation in the size of the holes caused by SN from 35% to below 10%. The method extends the patterning limits of transistor contact holes to below 20 nm.

Uniformly sized nanoparticles can remove fluctuations in contact hole dimensions patterned in poly(methyl methacrylate) (PMMA) photoresist films by electron beam (E-beam) lithography. The process involves electrostatic funneling to center and deposit nanoparticles in contact holes, followed by photoresist reflow and plasma- and wet-etching steps.

Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has ...

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...

Single-Digit Nanometer Electron-Beam Lithography with an Aberration-Corrected Scanning Transmission Electron Microscope

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by employing an aberration-corrected scanning transmission electron microscope as the exposure tool. Here, we present results of single-digit nanometer patterning of two widely used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. The method achieves sub-5 nanometer features in poly (methyl methacrylate) and sub-10 nanometer resolution in hydrogen silsesquioxane. High-fidelity transfer of these patterns into target materials of choice can be performed using metal lift-off, plasma etch, and resist infiltration with organometallics.

We use an aberration-corrected scanning transmission electron microscope to define single-digit nanometer patterns in two widely-used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. Resist patterns can be replicated in target materials of choice with single-digit nanometer fidelity using liftoff, plasma etching, and resist infiltration by organometallics.

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by ...

Fabrication of Nanoheight Channels Incorporating Surface Acoustic Wave Actuation via Lithium Niobate for Acoustic Nanofluidics

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order surface acoustic wave (SAW) devices generate tremendous acceleration on their surface, up to 108 m/s2, in turn responsible for many of the observed effects that have come to define acoustofluidics: acoustic streaming and acoustic radiation forces. These effects have been used for particle, cell, and fluid manipulation at the microscale, although more recently SAW has been used to produce similar phenomena at the nanoscale through an entirely different set of mechanisms. Controllable nanoscale fluid manipulation offers a broad range of opportunities in ultrafast fluid pumping and biomacromolecule dynamics useful for physical and biological applications. Here, we demonstrate nanoscale-height channel fabrication via room-temperature lithium niobate (LN) bonding integrated with a SAW device. We describe the entire experimental process including nano-height channel fabrication via dry etching, plasma-activated bonding on lithium niobate, the appropriate optical setup for subsequent imaging, and SAW actuation. We show representative results for fluid capillary filling and fluid draining in a nanoscale channel induced by SAW. This procedure offers a practical protocol for nanoscale channel fabrication and integration with SAW devices useful to build upon for future nanofluidics applications.

We demonstrate fabrication of nanoheight channels with the integration of surface acoustic wave actuation devices upon lithium niobate for acoustic nanofluidics via liftoff photolithography, nano-depth reactive ion etching, and room-temperature plasma surface-activated multilayer bonding of single-crystal lithium niobate, a process similarly useful for bonding lithium niobate to oxides.

Controlled nanoscale manipulation of fluids is known to be exceptionally difficult due to the dominance of surface and viscous forces. Megahertz-order ...

Nanoscale Characterization of Liquid-Solid Interfaces by Coupling Cryo-Focused Ion Beam Milling with Scanning Electron Microscopy and Spectroscopy

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar energy and fuel generation, and electrochemical energy storage. Nanoscale characterization of such interfaces has recently been achieved using cryogenic electron microscopy, thereby providing a new path to advancing our fundamental understanding of interface processes.
This contribution provides a practical guide to mapping the structure and chemistry of solid-liquid interfaces in materials and devices using an integrated cryogenic electron microscopy approach. In this approach, we pair cryogenic sample preparation which allows stabilization of solid-liquid interfaces with cryogenic focused ion beam (cryo-FIB) milling to create cross-sections through these complex buried structures. Cryogenic scanning electron microscopy (cryo-SEM) techniques performed in a dual-beam FIB/SEM enable direct imaging as well as chemical mapping at the nanoscale. We discuss practical challenges, strategies to overcome them, as well as protocols for obtaining optimal results. While we focus in our discussion on interfaces in energy storage devices, the methods outlined are broadly applicable to a range of fields where solid-liquid interface play a key role.

Cryogenic Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) techniques can provide key insights into the chemistry and morphology of intact solid-liquid interfaces. Methods for preparing high quality Energy Dispersive X-ray (EDX) spectroscopic maps of such interfaces are detailed, with a focus on energy storage devices.

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar ...

Focused Ion Beams

Source: Sina Shahbazmohamadi and <a href="https://www.jove.com/author/Peiman_Shahbeigi-Roodposhti">Peiman Shahbeigi-Roodposhti-Roodposhti</a>, School of Engineering, University of Connecticut, Storrs, CT
As electron microscopes become more complex and widely used in research labs, it becomes more of a necessity to introduce their capabilities. Focused ion beam (FIB) is an instrument that can be employed in order to fabricate, trim, analyze and characterize materials on mico- and nano-scales in a wide variety of fields from nano-electronics to medicine. FIB systems can be thought of as a beam of ions that can be used to mill (sputter), deposit, and image materials on micro- and nano-scales. The ion columns of FIBs are commonly integrated with the electron columns of scanning electron microscopes (SEMs).
The goal of this experiment is to introduce the state of the art in focused ion beam technologies and to show how these instruments can be used in order to fabricate structures that are as small as the smallest membranes that are found in the human body.

Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

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