scholarly journals Simulation of electron transport during electron-beam-induced deposition of nanostructures

2013 ◽  
Vol 4 ◽  
pp. 781-792 ◽  
Author(s):  
Francesc Salvat-Pujol ◽  
Harald O Jeschke ◽  
Roser Valentí
Keyword(s):  
Electron Beam ◽  
Electron Transport ◽  
Radiation Transport ◽  
Secondary Electrons ◽  
Electron Trajectories ◽  
Backscattered Electrons ◽  
Multi Scale ◽  
Different Depths ◽  
Electron Beam Induced Deposition ◽  
Insight Into

We present a numerical investigation of energy and charge distributions during electron-beam-induced growth of tungsten nanostructures on SiO2 substrates by using a Monte Carlo simulation of the electron transport. This study gives a quantitative insight into the deposition of energy and charge in the substrate and in the already existing metallic nanostructures in the presence of the electron beam. We analyze electron trajectories, inelastic mean free paths, and the distribution of backscattered electrons in different compositions and at different depths of the deposit. We find that, while in the early stages of the nanostructure growth a significant fraction of electron trajectories still interacts with the substrate, when the nanostructure becomes thicker the transport takes place almost exclusively in the nanostructure. In particular, a larger deposit density leads to enhanced electron backscattering. This work shows how mesoscopic radiation-transport techniques can contribute to a model that addresses the multi-scale nature of the electron-beam-induced deposition (EBID) process. Furthermore, similar simulations can help to understand the role that is played by backscattered electrons and emitted secondary electrons in the change of structural properties of nanostructured materials during post-growth electron-beam treatments.

scholarly journals Surface excitations in the modelling of electron transport for electron-beam-induced deposition experiments

2015 ◽  
Vol 6 ◽  
pp. 1260-1267 ◽  
Author(s):  
Francesc Salvat-Pujol ◽  
Roser Valentí ◽  
Wolfgang S Werner
Keyword(s):  
Electron Beam ◽  
Electron Transport ◽  
Primary Energy ◽  
Primary Electron ◽  
Sizeable Fraction ◽  
The Subject ◽  
Electron Beam Induced Deposition ◽  
The One ◽  
Electron Energy Loss ◽  
General Perspective

The aim of the present overview article is to raise awareness of an essential aspect that is usually not accounted for in the modelling of electron transport for focused-electron-beam-induced deposition (FEBID) of nanostructures: Surface excitations are on the one hand responsible for a sizeable fraction of the intensity in reflection-electron-energy-loss spectra for primary electron energies of up to a few kiloelectronvolts and, on the other hand, they play a key role in the emission of secondary electrons from solids, regardless of the primary energy. In this overview work we present a general perspective of recent works on the subject of surface excitations and on low-energy electron transport, highlighting the most relevant aspects for the modelling of electron transport in FEBID simulations.

Electron Transport Properties of Pt Nanoarch Fabricated by Electron-Beam-Induced Deposition

2011 ◽  
Vol 50 (6) ◽  
pp. 06GG14
Author(s):  
Fujio Wakaya ◽  
Kunio Takamoto ◽  
Tsuyoshi Teraoka ◽  
Katsuhisa Murakami ◽  
Satoshi Abo ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Transport ◽  
Transport Properties ◽  
Electron Transport Properties ◽  
Electron Beam Induced Deposition

scholarly journals The role of low-energy electrons in focused electron beam induced deposition: four case studies of representative precursors

2015 ◽  
Vol 6 ◽  
pp. 1904-1926 ◽  
Author(s):  
Rachel M Thorman ◽  
Ragesh Kumar T. P. ◽  
D Howard Fairbrother ◽  
Oddur Ingólfsson
Keyword(s):  
Electron Beam ◽  
Gas Phase ◽  
Primary Electron ◽  
Low Energy ◽  
Primary Electron Beam ◽  
Secondary Electrons ◽  
Low Energy Electrons ◽  
Low Energy Electron ◽  
Precursor Molecules ◽  
Insight Into

Focused electron beam induced deposition (FEBID) is a single-step, direct-write nanofabrication technique capable of writing three-dimensional metal-containing nanoscale structures on surfaces using electron-induced reactions of organometallic precursors. Currently FEBID is, however, limited in resolution due to deposition outside the area of the primary electron beam and in metal purity due to incomplete precursor decomposition. Both limitations are likely in part caused by reactions of precursor molecules with low-energy (<100 eV) secondary electrons generated by interactions of the primary beam with the substrate. These low-energy electrons are abundant both inside and outside the area of the primary electron beam and are associated with reactions causing incomplete ligand dissociation from FEBID precursors. As it is not possible to directly study the effects of secondary electrons in situ in FEBID, other means must be used to elucidate their role. In this context, gas phase studies can obtain well-resolved information on low-energy electron-induced reactions with FEBID precursors by studying isolated molecules interacting with single electrons of well-defined energy. In contrast, ultra-high vacuum surface studies on adsorbed precursor molecules can provide information on surface speciation and identify species desorbing from a substrate during electron irradiation under conditions more representative of FEBID. Comparing gas phase and surface science studies allows for insight into the primary deposition mechanisms for individual precursors; ideally, this information can be used to design future FEBID precursors and optimize deposition conditions. In this review, we give a summary of different low-energy electron-induced fragmentation processes that can be initiated by the secondary electrons generated in FEBID, specifically, dissociative electron attachment, dissociative ionization, neutral dissociation, and dipolar dissociation, emphasizing the different nature and energy dependence of each process. We then explore the value of studying these processes through comparative gas phase and surface studies for four commonly-used FEBID precursors: MeCpPtMe3, Pt(PF3)4, Co(CO)3NO, and W(CO)6. Through these case studies, it is evident that this combination of studies can provide valuable insight into potential mechanisms governing deposit formation in FEBID. Although further experiments and new approaches are needed, these studies are an important stepping-stone toward better understanding the fundamental physics behind the deposition process and establishing design criteria for optimized FEBID precursors.

Electron Transport Properties of Pt Nanoarch Fabricated by Electron-Beam-Induced Deposition

2011 ◽  
Vol 50 (6S) ◽  
pp. 06GG14 ◽  
Author(s):  
Fujio Wakaya ◽  
Kunio Takamoto ◽  
Tsuyoshi Teraoka ◽  
Katsuhisa Murakami ◽  
Satoshi Abo ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Transport ◽  
Transport Properties ◽  
Electron Transport Properties ◽  
Electron Beam Induced Deposition

Comparison of Channeling Contrast between Ion and Electron Images

2013 ◽  
Vol 19 (2) ◽  
pp. 344-349 ◽  
Author(s):  
L.A. Giannuzzi ◽  
J.R. Michael
Keyword(s):  
Electron Beam ◽  
Critical Angle ◽  
Incident Beam ◽  
Secondary Electrons ◽  
Crystalline Materials ◽  
Multiple Images ◽  
Electron Channeling ◽  
Backscattered Electrons ◽  
Ion Channeling ◽  
Primary Contribution

AbstractIon channeling contrast (iCC) and electron channeling contrast (eCC) are caused by variation in signal resulting from changes in the angle of the incident beam and the crystal lattice with respect to the target. iCC is directly influenced by the incident ion range in crystalline materials. The ion range is larger for low-index crystal orientated grains, resulting in the emission of fewer secondary electrons at the surface yielding a lower signal. Ions are stopped closer to the surface for off-axis grains, resulting in the emission of many secondary electrons yielding a higher signal. Conversely, backscattered electrons (BSEs) are the primary contribution to eCC. BSEs are diffracted or channeled to form an electron channeling pattern (ECP). The BSE emission of the ECP peaks when the electron beam is normal to the surface of an on-axis grain, and therefore a bright signal is observed. Thus, iCC and eCC images yield inverse contrast behavior for on-axis oriented grains. Since there is a critical angle associated with particle channeling, accurately determining grain boundary locations require the acquisition of multiple images obtained at different tilt conditions.

scholarly journals Multiscale simulation of the focused electron beam induced deposition process

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Pablo de Vera ◽  
Martina Azzolini ◽  
Gennady Sushko ◽  
Isabel Abril ◽  
Rafael Garcia-Molina ◽  
...  
Keyword(s):  
Electron Beam ◽  
Essential Role ◽  
Molecular Level ◽  
Radiation Transport ◽  
Deposition Process ◽  
Multiscale Simulation ◽  
Comprehensive Description ◽  
Depth Analysis ◽  
Electron Beam Induced Deposition ◽  
Beam Parameters

AbstractFocused 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 $$\hbox {W(CO)}_6$$ W(CO) 6 deposition on $$\hbox {SiO}_2$$ SiO 2 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.

Dynamic Model of Electron Beam Induced Deposition (EBID) of Residual Hydrocarbons in Electron Microscopy

2006 ◽  
Author(s):  
Konrad Rykaczewski ◽  
Ben White ◽  
Jenna Browning ◽  
Andrew D. Marshall ◽  
Andrei G. Fedorov
Keyword(s):  
Growth Rate ◽  
Electron Beam ◽  
Electron Transport ◽  
Mass Transport ◽  
Dynamic Model ◽  
Surface Diffusion ◽  
Secondary Electron ◽  
High Vacuum ◽  
Dissociation Reaction ◽  
Electron Beam Induced Deposition

Adsorbed species surface diffusion Electron beam induced deposition (EBID) of residuals carbon can be either a contamination problem or can provide a basis for 3-D nanofabrication and nanoscale metrology. In this process a solid deposit is formed at the point of impact of the electron beam due to the decomposition of residual hydrocarbon species adsorbed on the solid substrate. The first observation of EBID can be traced to miscroscopists who noticed the growth of thin films of carbon while imaging using an electron microscope. The process was referred to as "contamination" because of its adverse effects on the microscope's imaging quality. Later, it has been demonstrated that with appropriate control of the electron beam this problematic contamination can be exploited to deposit three dimensional nanostructures with the spatial resolution down to 10nm. Numerous researchers have experimentally explored various factors influencing EBID growth rate and geometry of the deposit. To date, the most comprehensive theoretical model predicting the shape of the deposit in EBID is due to Silvis-Cividjian[1]. However, this model accounts for electron transport only. A few, fairly rudimentary models have also been developed for mass transport in EBID, but usually limited to rather simplistic treatment of electron transport. To this end, we have developed a comprehensive dynamic model of EBID coupling mass transport, electron transport and scattering, and species decomposition to predict deposition of carbon nano-dots. The simulations predict the local species and electron density distributions, as well as the 3-D profile and the growth rate of the deposit. Since the process occurs in a high vacuum environment surface diffusion is considered as the primary transport mode of surface-adsorbed hydrocarbon precursor. Transport, scattering, and absorption of primary electron as well as secondary electron generation are treated using the Monte Carlo methods. Low energy secondary electrons (SE) are the major contributors to hydrocarbon decomposition due to their energy range matching peak dissociation reaction cross section energies for precursor molecules. The local SE flux at the substrate and at the free surface of the growing deposit is computed using the Fast Secondary Electron (FSE) model. When combined with the total dissociation reaction corssection and the local hydrocarbon surface concentration, this allows us to compute the local deposition rate. The deposition rates are then used to predict the shape profile evolution of the deposit. Simulation results are compared with an AFM imaging of carbon EBID.

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