Electrical resistance of electron beam induced deposits from tungsten hexacarbonyl

Hoyle, P. C.; Ogasawara, Masataka; Cleaver, J. R. A.; Ahmed, H.

doi:10.1063/1.109133

Cited by 38 publications

(50 citation statements)

References 6 publications

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“…Increasing the nitrogen flux, carbon remained largely constant, while the amount of oxygen increased significantly (Figure 4b). Particularly the increase in oxygen content with increasing flux is a symptom of the decreasing purity due to the incorporation of precursor that has not been fully decomposed by the electron beam (ELR) [10,11,17]. This assumption is supported by the fact that at higher beam currents oxygen contamination is decreasing significantly at constant volume (Fig.…”

Section: Resultssupporting

confidence: 65%

“…An important result of this work is the accurate definition of the transition from PLR to ELR. This provides a keyadvantage because while PLR deposits are typically of high purity but slow to deposit, structures synthesized in the ELR are usually characterized by fast deposition and decreased purity [10,17,20]. Both, a high rate of deposition reducing the processing time as well as a high purity are desirable.…”

Section: Resultsmentioning

confidence: 99%

“…The main contaminants detected by EDX are O and C, while no traces of nitrogen have been detected. Particularly, O and C may both originate from residual precursor fragments that are incorporated in the structures and [17] from residual gas (RG) present in the SEM chamber. The RG in the high vacuum chambers is mainly composed of H 2 , He, O 2 , N 2 , H 2 O and C-containing species.…”

Section: Resultsmentioning

confidence: 99%

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Nitrogen as a carrier gas for regime control in focused electron beam induced deposition

et al. 2014

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The synthesis of ferromagnetic nanostructures has received great attention over the past few years. These structures are usually manufactured by lithographic structuring of a substrate, blanket deposition of the desired magnetic material and a subsequent lift-off process [1,2]. As a successful alternative to this multi-step procedure, focused electron beam induced deposition (FEBID) allows the mask-and resist-less nanofabrication of planar and three dimensional (3D) structures [3]. In FEBID, the focused electron beam (FEB) of a scanning electron microscope (SEM) locally supplies the energy needed to activate the precursor and induce a local chemical vapour deposition process. The direct-write nature of FEBID enables high flexibility in the (three dimensional) design of the deposited objects, avoiding complex and time-consuming multi-step lithography processes [4,5]. This makes FEBID an excellent candidate for research and prototyping applications, such as circuit editing or the design and fabrication of various nanosystems, e.g., in sensing applications as well as data-storage and processing [6][7][8]. In FEBID a variety of precursors containing magnetic elements is available [3,5]. High purity magnetic materials based on Fe and Co were already synthesized by FEBID using carbonyl (CO) based precursors, for their application in magnetic sensing and logic technologies [8,9]. The choice of these chemicals is driven by the relatively "clean" decomposition path and their high volatility [3]. It has been shown [3, 10, 11] that precursor flow as well as the FEB current are important factors effecting chemical and geometric properties of the deposit. To further enhance the growth rate using CO-based substances, a sufficiently high precursor flux is necessary [12]. For this reason the whole gas injection system (GIS) is often heated up in order to increase the vapour pressure and thereby precursor flux to the deposition area [13]. However, temperature gradients along the delivery system may lead to undesirable re-condensation or deposition of precursor molecules Abstract: This work reports on focused electron beam induced deposition (FEBID) using a custom built gas injection system (GIS) equipped with nitrogen as a gas carrier. We have deposited cobalt from Co 2 (CO) 8 , which is usually achieved by a heated GIS. In contrast to a heated GIS, our strategy allows avoiding problems caused by eventual temperature gradients along the GIS. Moreover, the use of the gas carrier enables a high control over process conditions and consequently the properties of the synthesized nanostructures. Chemical composition and growth rate are investigated by energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM), respectively. We demonstrate that the N 2 flux is strongly affecting the deposit growth rate without the need of heating the precursor in order to increase its vapour pressure. Particularly, AFM volume estimation of the deposited structures showed that increasing the nitrogen resulted in an enhanced deposition ...

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Section: Resultssupporting

confidence: 65%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Nitrogen as a carrier gas for regime control in focused electron beam induced deposition

et al. 2014

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“…In the literature various methods are discussed to obtain an increase of the electrical conductivity [9]. Among these methods are: careful selection of the electron beam parameters used for the deposition [26], annealing of the samples in reactive atmosphere [27] and deposition from carbon-free precursors [28]. Postgrowth electron beam irradiation has been used to tailor the grain size of Pt nanocrystallites and to increase the electrical conductivity in deposits grown from the carbon-free Pt(PF3)4 precursor [29].…”

Section: Discussionmentioning

confidence: 99%

Tuning the electrical conductivity of Pt-containing granular metals by postgrowth electron irradiation

Porrati

Sachser

Schwalb

et al. 2011

Journal of Applied Physics

101

171

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We have fabricated Pt-containing granular metals by focused electron beam induced deposition from the (CH3)3CH3C5H4Pt precursor gas. The granular metals are made of platinum nanocrystallites embedded in a carbonaceous matrix. We have exposed the asgrown nanocomposites to low energy electron beam irradiation and we have measured the Finally, by means of AFM measurements we observe a reduction of the volume of the samples with increasing irradiation time which we attribute to the removal of carbon molecules.

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“…The local precursor coverage on the deposition spot determines whether the process is conducted in the electron-limited regime or in the precursorlimited regime [9,10]. This way the precursor coverage determines the deposits minimum dimensions and geometry [11], the deposition rate [12,13], and its chemical composition [13,14]. Not only for fundamental insights but also for practical reproducibility of each deposition one must know and reproduce the same precursor density at the electron exposed deposition areas.…”

Section: Introductionmentioning

confidence: 99%

Mapping of local argon impingement on a virtual surface: an insight for gas injection during FEBID

et al. 2014

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During the last decades, focused electron beam induced deposition (FEBID) has become a successful approach for direct-write fabrication of nanodevices. Such a deposition technique relies on the precursor supply to the sample surface which is typically accomplished by a gas injection system using a tube-shaped injector nozzle. This precursor injection strategy implies a position-dependent concentration gradient on the surface, which affects the geometry and chemistry of the final nanodeposit. Although simulations already proposed the local distribution of nozzle-borne gas molecules impinging on the surface, this isolated step in the FEBID process has never been experimentally measured yet. This work experimentally investigates the local distribution of impinging gas molecules on the sample plane, isolating the direct impingement component from surface diffusion or precursor depletion by deposition. The experimental setup used in this work maps and quantifies the local impinging rate of argon gas over the sample plane. This setup simulates the identical conditions for a precursor molecule during FEBID. Argon gas was locally collected with a sniffer tube, which is directly connected to a residual gas analyzer for quantification. The measured distribution of impinging gas molecules showed a strong position dependence. Indeed, a 300-lm shift of the deposition area to a position further away from the impingement center spot resulted in a 50 % decrease in the precursor impinging rate on the surface area. With the same parameters, the precursor distribution was also simulated by a Monte Carlo software by Friedli and Utke and showed a good correlation between the empirical and the simulated precursor distribution. The results hereby presented underline the importance of controlling the local precursor flux conditions in order to obtain reproducible and comparable deposition results in FEBID.

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Electrical resistance of electron beam induced deposits from tungsten hexacarbonyl

Abstract: Synchrotron radiation induced chemical vapor deposition of thin films from metal hexacarbonyls* Lowtemperature chemical vapor deposition of tungsten from tungsten hexacarbonyl

Cited by 38 publications

References 6 publications

Nitrogen as a carrier gas for regime control in focused electron beam induced deposition

Nitrogen as a carrier gas for regime control in focused electron beam induced deposition

Tuning the electrical conductivity of Pt-containing granular metals by postgrowth electron irradiation

Mapping of local argon impingement on a virtual surface: an insight for gas injection during FEBID

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