Simulation Informed CAD for 3D Nanoprinting

Condensed Matter Systems Exposed to Radiation: Multiscale Theory, Simulations, and Experiment

This roadmap reviews the new, highly interdisciplinary research field studying the behavior of condensed matter systems exposed to radiation. The Review highlights several recent advances in the field and provides a roadmap for the development of the field over the next decade. Condensed matter systems exposed to radiation can be inorganic, organic, or biological, finite or infinite, composed of different molecular species or materials, exist in different phases, and operate under different thermodynamic conditions. Many of the key phenomena related to the behavior of irradiated systems are very similar and can be understood based on the same fundamental theoretical principles and computational approaches. The multiscale nature of such phenomena requires the quantitative description of the radiation-induced effects occurring at different spatial and temporal scales, ranging from the atomic to the macroscopic, and the interlinks between such descriptions. The multiscale nature of the effects and the similarity of their manifestation in systems of different origins necessarily bring together different disciplines, such as physics, chemistry, biology, materials science, nanoscience, and biomedical research, demonstrating the numerous interlinks and commonalities between them. This research field is highly relevant to many novel and emerging technologies and medical applications.

3D Nanoprinting Replication Enhancement Using a Simulation-Informed Analytical Model for Electron Beam Exposure Dose Compensation

3D nanoprinting, using focused electron beam-induced deposition, is prone to a common structural artifact arising from a temperature gradient that naturally evolves during deposition, extending from the electron beam impact region (BIR) to the substrate. Inelastic electron energy loss drives the Joule heating and surface temperature variations lead to precursor surface concentration variations due, in most part, to temperature-dependent precursor surface desorption. The result is unwanted curvature when prescribing linear segments in 3D objects, and thus, complex geometries contain distortions. Here, an electron dose compensation strategy is presented to offset deleterious heating effects; the Decelerating Beam Exposure Algorithm, or DBEA, which corrects for nanowire bending a priori, during computer-aided design, uses an analytical solution derived from information gleaned from 3D nanoprinting simulations. Electron dose modulation is an ideal solution for artifact correction because variations in electron dose have no influence on temperature. Thus, the generalized compensation strategy revealed here will help advance 3D nanoscale printing fidelity for focused electron beam-induced deposition.

Controlled Morphological Bending of 3D-FEBID Structures via Electron Beam Curing

Focused electron beam induced deposition (FEBID) is one of the few additive, direct-write manufacturing techniques capable of depositing complex 3D nanostructures. In this work, we explore post-growth electron beam curing (EBC) of such platinum-based FEBID deposits, where free-standing, sheet-like elements were deformed in a targeted manner by local irradiation without precursor gas present. This process diminishes the volumes of exposed regions and alters nano-grain sizes, which was comprehensively characterized by SEM, TEM and AFM and complemented by Monte Carlo simulations. For obtaining controlled and reproducible conditions for smooth, stable morphological bending, a wide range of parameters were varied, which will here be presented as a first step towards using local EBC as a tool to realize even more complex nano-architectures, beyond current 3D-FEBID capabilities, such as overhanging structures. We thereby open up a new prospect for future applications in research and development that could even be further developed towards functional imprinting.

FEBID 3D-Nanoprinting at Low Substrate Temperatures: Pushing the Speed While Keeping the Quality

High-fidelity 3D printing of nanoscale objects is an increasing relevant but challenging task. Among the few fabrication techniques, focused electron beam induced deposition (FEBID) has demonstrated its high potential due to its direct-write character, nanoscale capabilities in 3D space and a very high design flexibility. A limitation, however, is the low fabrication speed, which often restricts 3D-FEBID for the fabrication of single objects. In this study, we approach that challenge by reducing the substrate temperatures with a homemade Peltier stage and investigate the effects on Pt based 3D deposits in a temperature range of 5–30 °C. The findings reveal a volume growth rate boost up to a factor of 5.6, while the shape fidelity in 3D space is maintained. From a materials point of view, the internal nanogranular composition is practically unaffected down to 10 °C, followed by a slight grain size increase for even lower temperatures. The study is complemented by a comprehensive discussion about the growth mechanism for a more general picture. The combined findings demonstrate that FEBID on low substrate temperatures is not only much faster, but practically free of drawbacks during high fidelity 3D nanofabrication.

Expanding 3D Nanoprinting Performance by Blurring the Electron Beam

Additive, direct-write manufacturing via a focused electron beam has evolved into a reliable 3D nanoprinting technology in recent years. Aside from low demands on substrate materials and surface morphologies, this technology allows the fabrication of freestanding, 3D architectures with feature sizes down to the sub-20 nm range. While indispensably needed for some concepts (e.g., 3D nano-plasmonics), the final applications can also be limited due to low mechanical rigidity, and thermal- or electric conductivities. To optimize these properties, without changing the overall 3D architecture, a controlled method for tuning individual branch diameters is desirable. Following this motivation, here, we introduce on-purpose beam blurring for controlled upward scaling and study the behavior at different inclination angles. The study reveals a massive boost in growth efficiencies up to a factor of five and the strong delay of unwanted proximal growth. In doing so, this work expands the design flexibility of this technology.

Multiscale simulation of the focused electron beam induced deposition process

Focused electron beam induced deposition (FEBID) is a powerful technique for 3D-printing of complex nanodevices. However, for resolutions below 10 nm, it struggles to control size, morphology and composition of the structures, due to a lack of molecular-level understanding of the underlying irradiation-driven chemistry (IDC). Computational modeling is a tool to comprehend and further optimize FEBID-related technologies. Here we utilize a novel multiscale methodology which couples Monte Carlo simulations for radiation transport with irradiation-driven molecular dynamics for simulating IDC with atomistic resolution. Through an in depth analysis of [Formula: see text] deposition on [Formula: see text] and its subsequent irradiation with electrons, we provide a comprehensive description of the FEBID process and its intrinsic operation. Our analysis reveals that simulations deliver unprecedented results in modeling the FEBID process, demonstrating an excellent agreement with available experimental data of the simulated nanomaterial composition, microstructure and growth rate as a function of the primary beam parameters. The generality of the methodology provides a powerful tool to study versatile problems where IDC and multiscale phenomena play an essential role.

Mechanical Properties of 3D Nanostructures Obtained by Focused Electron/Ion Beam-Induced Deposition: A Review

This article reviews the state-of-the -art of mechanical material properties and measurement methods of nanostructures obtained by two nanoscale additive manufacturing methods: gas-assisted focused electron and focused ion beam-induced deposition using volatile organic and organometallic precursors. Gas-assisted focused electron and ion beam-induced deposition-based additive manufacturing technologies enable the direct-write fabrication of complex 3D nanostructures with feature dimensions below 50 nm, pore-free and nanometer-smooth high-fidelity surfaces, and an increasing flexibility in choice of materials via novel precursors. We discuss the principles, possibilities, and literature proven examples related to the mechanical properties of such 3D nanoobjects. Most materials fabricated via these approaches reveal a metal matrix composition with metallic nanograins embedded in a carbonaceous matrix. By that, specific material functionalities, such as magnetic, electrical, or optical can be largely independently tuned with respect to mechanical properties governed mostly by the matrix. The carbonaceous matrix can be precisely tuned via electron and/or ion beam irradiation with respect to the carbon network, carbon hybridization, and volatile element content and thus take mechanical properties ranging from polymeric-like over amorphous-like toward diamond-like behavior. Such metal matrix nanostructures open up entirely new applications, which exploit their full potential in combination with the unique 3D additive manufacturing capabilities at the nanoscale.

Focused Electron Beam-Based 3D Nanoprinting for Scanning Probe Microscopy: A Review

Scanning probe microscopy (SPM) has become an essential surface characterization technique in research and development. By concept, SPM performance crucially depends on the quality of the nano-probe element, in particular, the apex radius. Now, with the development of advanced SPM modes beyond morphology mapping, new challenges have emerged regarding the design, morphology, function, and reliability of nano-probes. To tackle these challenges, versatile fabrication methods for precise nano-fabrication are needed. Aside from well-established technologies for SPM nano-probe fabrication, focused electron beam-induced deposition (FEBID) has become increasingly relevant in recent years, with the demonstration of controlled 3D nanoscale deposition and tailored deposit chemistry. Moreover, FEBID is compatible with practically any given surface morphology. In this review article, we introduce the technology, with a focus on the most relevant demands (shapes, feature size, materials and functionalities, substrate demands, and scalability), discuss the opportunities and challenges, and rationalize how those can be useful for advanced SPM applications. As will be shown, FEBID is an ideal tool for fabrication / modification and rapid prototyping of SPM-tipswith the potential to scale up industrially relevant manufacturing.