Continuum models of focused electron beam induced processing

Toth, Milos; Lobo, Charlene; Friedli, Vinzenz; Szkudlarek, Aleksandra; Utke, Ivo

doi:10.1515/nano.bjneah.6.157

Cited by 16 publications

(25 citation statements)

References 61 publications

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“…From this the required spatial and energy distribution of the secondary electrons can be derived as input for a reaction-diffusion equation describing the spatial and temporal evolution of the precursor density on the growth front of the developing deposit. This latter part, commonly known as the FEBIP continuum model, has recently been reviewed by Milos Toth and colleagues for the 2D case [154] and is able to simulate both, deposition and electron-induced etching, can handle complex adsorption processes [155], and can deal with etch processes that proceed through multiple reaction pathways with several reaction products present at the substrate surface. [24].…”

Section: Simulating 3d Growthmentioning

confidence: 99%

Focused electron beam induced deposition meets materials science

Huth

Porrati

Dobrovolskiy

2018

Microelectronic Engineering

157

172

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simulation-assisted growth of complex three-dimensional nano-architectures is also covered. In the review particular emphasis is laid on conceptual clarity in the description of the different developments, which is reflected in the mostly schematic nature of the presented figures, as well as in the recurring final sub-sections for each of the main topics discussing the respective "challenges and perspectives".

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Section: Simulating 3d Growthmentioning

confidence: 99%

Focused electron beam induced deposition meets materials science

Huth

Porrati

Dobrovolskiy

2018

Microelectronic Engineering

157

172

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“…However, when averaged over the characteristic deposition times (usually in the order of a few seconds to tens of minutes), a good approximation can be achieved by describing the height h of the evolving deposit as a continuous function of dwell time t and radial distance r from the beam center h(t, r). 45 Overlapping a large number of such deposits produces out of plane growth.…”

Section: Introductionmentioning

confidence: 99%

“…Equations 3 and 4 can be solved analytically, describing the depletion of gas coverage under electron beam dissociation, and subsequent growth of the induced deposit (see Supporting Information S1.1). 45 To specify the the spatial dependence of deposits, the profile of the effective flux of electrons inducing decomposition as a function of the radial distance from the electron beam ν el = ν el (r) is required. For focused beams, this can be approximated by a Gaussian function: 21…”

Section: Introductionmentioning

confidence: 99%

“…To allow for an analytical solution, in the above analysis we did not consider the effect of diffusion, which may become important in FEBID under mass-transport limited conditions. 45 However, in the context of Langmuir FEBID, the addition of diffusion would only alter the relevant timescales by speeding up the gas dynamics, as shown in Supporting Information S2. The separable form of deposit evolution could also be recovered in this case, albeit with a more complex form for the spatial part s(r).…”

Section: Introductionmentioning

confidence: 99%

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Layer-by-Layer Growth of Complex-Shaped Three-Dimensional Nanostructures with Focused Electron Beams

et al. 2019

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The fabrication of three-dimensional (3D) nanostructures is of great interest to many areas of nanotechnology currently challenged by fundamental limitations of conventional lithography. One of the most promising direct-write methods for 3D nanofabrication is focused electron beam-induced deposition (FEBID), owing to its high spatial resolution and versatility. Here we extend FEBID to the growth of complex-shaped 3D nanostructures by combining the layer-by-layer approach of conventional macroscopic 3D printers and the proximity effect correction of electron beam lithography. This framework is based on the continuum FEBID model and is capable of adjusting for a wide range of effects present during deposition, including beam-induced heating, defocussing and gas flux anisotropies. We demonstrate the capabilities of our platform by fabricating free-standing nanowires, surfaces with varying curvatures and topologies, and general 3D objects, directly from standard stereolithography (STL) files and using different precursors. Real 3D nanoprinting as demonstrated here opens up exciting avenues for the study and exploitation of 3D nanoscale phenomena.

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“…This anisotropy can not be explained by conventional, established EBIE theory which is based on the mechanistic framework shown schematically in Figure 2(a), where the key role of energetic electrons is to dissociate surface-adsorbed precursor molecules. In the case of H 2 O EBIE of diamond, a possible pathway in this framework is the following [4,5]: [5,8,[11][12][13][14][15][16][17][18][19][20][21]. However, the model can not explain the etch rate anisotropy seen in Figure 1, unless different crystal planes give rise to significant variations in the electron dissociation cross-section of H 2 O adsorbates, the secondary electron emission yield, or the local coverage of precursor molecule adsorbates.…”

mentioning

confidence: 99%

Formation of Dynamic Topographic Patterns During Electron Beam Induced Etching of Diamond

Martin

Bahm²,

Bishop

et al. 2017

Microsc Microanal

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Spontaneous formation of geometric patterns is a fascinating, ubiquitous process that provides fundamental insights into the roles of symmetry breaking, anisotropy and nonlinear interactions in emergent phenomena [1][2][3]. Here we report dynamic, highly ordered topographic patterns on the surface of diamond that span multiple length scales and have a symmetry controlled by the chemical species of a precursor gas used in electron beam induced etching (EBIE). This behavior reveals an underlying etch rate anisotropy and an electron energy transfer pathway that has been overlooked by existing EBIE theory. We present an etch rate kinetics model that fully explains our results and is universally applicable to EBIE. Our findings can be exploited for controlled wetting, optical structuring and other emerging applications that require nano and micro-scale surface texturing.Electron beam induced etching (EBIE) [4, 5] is a high resolution, single step, direct-write nanofabrication technique in which a precursor gas and an electron beam are used to realize etching. To date, EBIE has been used to machine a wide range of materials using etch precursor such as oxygen, water, ammonia, nitrogen trifluoride, xenon difluoride and chlorine. Key advantages of EBIE include cite-specificity and the ability to etch materials such as diamond which are resistant to conventional chemical etch processes. Consequently, EBIE has recently been used to realize practical device components for use in photonics [6], plasmonics [7] and nanofluidics [8].In this work, we report an emergent pattern formation phenomenon caused by a chemical etch rate anisotropy in EBIE of single crystal diamond. The results reveal a shortcoming in existing, established EBIE theory which does not adequately explain the observed etch kinetics. We therefore propose a fundamental modification, whereby the critical role of energetic electrons is to transfer energy to and break bonds between surface atoms of the solid rather than to surface-adsorbed precursor molecules. The new EBIE model is confirmed experimentally, explains the observed patterns, and resolves * Equal contribution. † Igor.Aharonovich@uts.edu.au ‡ Milos.Toth@uts.edu.au long standing problems that have been identified in the EBIE literature. Figure 1(a) is a schematic illustration of EBIE performed using H 2 O precursor gas. Figure 1(b) shows images of topographic patterns that form on the surface of single crystal (001) oriented diamond during H 2 O EBIE performed at room temperature. A movie showing the pattern formation and evolution dynamics is provided as Supplementary Video #1. Such patterns have not been reported previously because their formation is inhibited by small amounts of residual hydrocarbon contaminants present on the etched surface. Residual contaminants are very common in electron microscopes, alter the surface termination during EBIE and give rise to a competing process of electron beam induced deposition of carbon [9].Etching initiates at scratches and other surface defects, which expand...

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Continuum models of focused electron beam induced processing

Abstract: This article is part of the Thematic Series "Focused electron beam induced processing".

Cited by 16 publications

References 61 publications

Focused electron beam induced deposition meets materials science

Focused electron beam induced deposition meets materials science

Layer-by-Layer Growth of Complex-Shaped Three-Dimensional Nanostructures with Focused Electron Beams

Formation of Dynamic Topographic Patterns During Electron Beam Induced Etching of Diamond

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