Unleashing nanofabrication through thermomechanical nanomolding

Liu, Naijia; Liu, Guannan; Raj, Arindam; Sohn, So Young; Morales-Acosta, M. D.; Liu, Jingbei; Schroers, Jan

doi:10.1126/sciadv.abi4567

Cited by 14 publications

(15 citation statements)

References 61 publications

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“…[21] This behavior is also seen during TMNM, where a small grain size feedstock requires a lower pressure for successful nanomolding compared to a large grain size or single crystal feedstock. The predicted length of the molded nanowire in 1D TMNM, L, is shown in Equation 1 [11] :…”

Section: Discussionmentioning

confidence: 99%

“…Recently, thermomechanical nanomolding (TMNM), a technique whereby a bulk feedstock of a desired material is pressed through a nanoporous mold at elevated temperatures and pressures, has been shown to yield high aspect ratio, single crystal nanowires over wafer-scale distances. [11][12][13][14] TMNM is materialagnostic, having been shown to work for a wide variety of materials including metals, [11,15] alloys, [11] and intermetallics. [16,17] TMNM of 1D nanowires relies on initial grain reorientation near the base of the nanowire as the bulk feedstock enters the nanopores of the mold to the preferred growth direction, which minimizes the total surface energy and interfacial diffusion barrier along the mold walls.…”

Section: Introductionmentioning

confidence: 99%

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Wafer‐Scale Fabrication of 2D Nanostructures via Thermomechanical Nanomolding

Kiani,

Sam,

Jung

et al. 2023

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With shrinking dimensions in integrated circuits, sensors, and functional devices, there is a pressing need to develop nanofabrication techniques with simultaneous control of morphology, microstructure, and material composition over wafer length scales. Current techniques are largely unable to meet all these conditions, suffering from poor control of morphology and defect structure or requiring extensive optimization or post‐processing to achieve desired nanostructures. Recently, thermomechanical nanomolding (TMNM) has been shown to yield single‐crystalline, high aspect ratio nanowires of metals, alloys, and intermetallics over wafer‐scale distances. Here, TMNM is extended for wafer‐scale fabrication of 2D nanostructures. Using In, Al, and Cu, nanomold nanoribbons with widths < 50 nm, depths ≈0.5–1 µm and lengths ≈7 mm into Si trenches at conditions compatible is successfully with back end of line processing . Through SEM cross‐section imaging and 4D‐STEM grain orientation maps, it is shown that the grain size of the bulk feedstock is transferred to the nanomolded structures up to and including single crystal Cu. Based on the retained microstructures of molded 2D Cu, the deformation mechanism during molding for 2D TMNM is discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Wafer‐Scale Fabrication of 2D Nanostructures via Thermomechanical Nanomolding

Kiani,

Sam,

Jung

et al. 2023

Small

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“…In TMNM, a bulk material of interest is extruded through a nanoporous mold at elevated temperatures (approximately 0.5 T m , where T m is the material’s melting point in Kelvin) and pressures (higher than 100 MPa) . Nanowire growth during TMNM is driven by lattice and interfacial diffusion along the mold channels. Additionally, grain reorientation occurs at the base of the nanowire in order to minimize the interfacial energy between the crystal and mold surfaces, leading to the formation of single-crystalline wires with consistent growth orientation .…”

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confidence: 99%

Nanomolding of Two-Dimensional Materials

Sam,

Tan,

Multunas

et al. 2023

ACS Nano

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Lateral confinement of layered, two-dimensional (2D) materials has uniquely enabled the exploration of several topological phenomena in electron transport due to the well-defined nanoscale cross-sections and perimeters. At present, research on laterally confined 2D materials is constrained by the lack of synthesis methods that can reliably and controllably produce nanostructures with narrow widths and high aspect ratios. We demonstrate the use of thermomechanical nanomolding (TMNM) to fabricate nanowires of six layered materials (Te, In2Se3, Bi2Te3, Bi2Se3, GaSe, and Sb2Te3) with widths of 40 nm and aspect ratios above 100. During molding, the van der Waals (vdW) layers rotate by 90° from the horizontal direction in the bulk feedstock to the vertical direction in the molded nanowire, such that the layers are aligned along the nanowire length. We find that interfacial diffusion and surface energy minimization drive nanowire formation during TMNM, often resulting in single-crystalline nanowires with consistent crystallographic orientation.

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“…We have recently developed a controlled and scalable nanofabrication method called thermomechanical nanomolding (TMNM) − that holds promise for obtaining single-crystal nanostructures. TMNM exhibits high control over the size and aspect ratio of the nanowires.…”

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confidence: 99%

“…The nanowires’ length and diameter are limited practically by the mold dimensions, but there is no fundamental limit to these features. We have demonstrated that TMNM can be applied to a wide range of materials, including metals, alloys, and ordered phases. ,− The underlying mechanism of TMNM is based on diffusion, specifically on interface diffusion (see Figure S2 Supporting Information) for temperatures above ∼0.4 T M , where T M is the melting temperature of the material. Notably, functional nanostructures fabricated by TMNM include superconductors, topological insulators, semiconductors, and phase change materials .…”

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confidence: 99%

Single-Crystal Nanostructure Arrays Forming Epitaxially through Thermomechanical Nanomolding

et al. 2021

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For nanostructures in advanced electronic and plasmonic systems, a single-crystal structure with controlled orientation is essential. However, the fabrication of such devices has remained challenging, as current nanofabrication methods often suffer from either polycrystalline growth or the difficulty of integrating single crystals with substrates in desired orientations and locations to create functional devices. Here we report a thermomechanical method for the controlled growth of single-crystal nanowire arrays, which enables the simultaneous synthesis, alignment, and patterning of nanowires. Within such diffusion-based thermomechanical nanomolding (TMNM), the substrate material diffuses into nanosized cavities under an applied pressure gradient at a molding temperature of ∼0.4 times the material’s melting temperature. Vertically grown face-centered cubic (fcc) nanowires with the [110] direction in an epitaxial relationship with the (110) substrate are demonstrated. The ability to control the crystal structure through the substrate takes TMNM a major step further, potentially allowing all fcc and body-centered cubic (bcc) materials to be integrated as single crystals into devices.

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Unleashing nanofabrication through thermomechanical nanomolding

Abstract: Thermomechanical nanomolding puts a wide range of materials combinations in reach for nanofabrication.

Cited by 14 publications

References 61 publications

Wafer‐Scale Fabrication of 2D Nanostructures via Thermomechanical Nanomolding

Wafer‐Scale Fabrication of 2D Nanostructures via Thermomechanical Nanomolding

Nanomolding of Two-Dimensional Materials

Single-Crystal Nanostructure Arrays Forming Epitaxially through Thermomechanical Nanomolding

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