Resolution in focused electron- and ion-beam induced processing

Utke, Ivo; Friedli, Vinzenz; Purrucker, Martin; Michler, Johann

doi:10.1116/1.2789441

Cited by 56 publications

(88 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When the number of incoming electrons was very high compared to the number of precursor molecules, and passes followed each other very quickly, almost all precursor molecules dissociated in the outer regions of the nested-L before they reached the center, and therefore growth of the center lines was limited. Similar results, where the combination of depletion and diffusion caused volcano shaped deposits, were obtained in practice 17 and in simulation 18 . However, with a waiting time between passes, precursor molecules had time to diffuse to depleted areas, which resulted in a higher, and more uniform, By combining the three patterning strategies, multiple passes, a waiting time between passes and 50-Hz synchronization, we were able to fabricate structures that show the true potential of EBID as a high resolution lithography tool.…”

supporting

confidence: 73%

Electron-beam-induced deposition of 3-nm-half-pitch patterns on bulk Si

Oven

Berwald

Berggren

et al. 2011

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

View full text Add to dashboard Cite

This paper demonstrates electron-beam-induced deposition of few-nm-width dense features on bulk samples by using a scanning electron-beam lithography system. To optimize the resultant features, three steps were taken: (1) features were exposed in a repetitive sequence, so as to build up the deposited features gradually across the entire pattern, and thus avoid proximity effects; (2) an additional delay was added between exposures to permit diffusion of reactants into the exposed area; and (3) the exposures were phase-synchronized to the dominant noise source (the 50-Hz line voltage) to minimize the effect of noise. The reasons these steps led to significant improvements in patterning resolution are discussed. KEYWORDSElectron-beam-induced-deposition, EBID, lines and spaces, Scanning Electron Microscope 2 MANUSCRIPT TEXTElectron-beam-induced-deposition (EBID) is a direct-write lithographic technique that uses a focused electron beam to make small material deposits [1][2][3][4][5] . By dissociating precursor molecules adsorbed on a surface, two-and three-dimensional structures can be created. The size of these structures can range from single-digit nanometer scale to several micrometers.The minimum feature size possible with EBID is smaller than 1 nm, as has been demonstrated by using finely focused beams in Scanning Transmission Electron Microscopes 6,7 . However, it is more convenient to use the much more user-friendly and widely spread platform of the Scanning Electron Microscope (SEM). We recently demonstrated that EBID can be used to create 3 nm dots in an SEM 8 . However, deposition was done on a thin membrane and imaging was done using a transmission detector, which, for such small structures, provides better contrast than a secondary electron detector. It was also found that, when decreasing the separation between deposits, they became broader. This broadening is due to proximity effects. There are two proximity effects that play a role here. First, the angular dependence of the secondary electron (SE) yield, which causes the growth rate to increase when the beam irradiates the slope of the deposit 9,10 . This results in non-linear growth when writing EBID lines. Second, during deposition of a line, secondary electrons escaping from that line may dissociate precursor molecules on the neighboring line, causing it to grow further 11-13 .The challenge we address now is to pattern lines and spaces, as densely as possible, on bulk material as opposed to a membrane. This challenge is important for applications in the fields of mask repair and circuit edit, as well as nano-scale prototyping. Working on bulk material forces us to use secondary electron (SE) detection for imaging the patterns, and to develop a 3 strategy to deal with the proximity effects. We will demonstrate the fabrication of dense patterns on a sub-10 nm scale on bulk silicon substrates using EBID.The EBID setup we used is an FEI Quanta 3D FEG Dual Beam machine, with a 30 keV electron beam energy and a smallest specified probe size of ~1...

show abstract

supporting

confidence: 73%

Electron-beam-induced deposition of 3-nm-half-pitch patterns on bulk Si

Oven

Berwald

Berggren

et al. 2011

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

View full text Add to dashboard Cite

show abstract

“…A similar curve progression can be observed in FEBID rate equation models describing the drop of deposition rate R at the crossover between the reaction-rate-limited (RRL) and the mass-transport-limited (MTL) regime [13,32]. As a drop of R would be directly reflected in the conductance data, the dwell-time dependent deposition rate was simulated using the rate equation model in the continuum limit and compared to the measured dS/dt max values.…”

Section: Resultsmentioning

confidence: 99%

Identifying the crossover between growth regimes via in-situ conductance measurements in focused electron beam induced deposition

Winhold¹,

Weirich²,

Schwalb³

et al. 2014

Nanofabrication

View full text Add to dashboard Cite

Focused electron beam induced deposition presents a promising technique for the fabrication of nanostructures. However, due to the dissociation of mostly organometallic precursor molecules employed for the deposition process, prepared nanostructures contain organic residues leading to rather low conductance of the deposits. Post-growth treatment of the structures by electron irradiation or in reactive atmospheres at elevated temperatures can be applied to purify the samples. Recently, an in-situ conductance optimization process involving evolutionary genetic algorithm techniques has been introduced leading to an increase of conductance by one order of magnitude for tungsten-based deposits using the precursor W(CO)6. This method even allows for the optimization of conductance of nano-structures for which post-growth treatment is not possible or desirable. However, the mechanisms responsible for the observed enhancement have not been studied in depth. In this work, we identified the dwell-time dependent change of conductivity of the samples to be the major contributor to the change of conductance. Specifically, the chemical composition drastically changes with a variation of dwelltime resulting in an increase of the metal content by 15 at% for short dwell-times. The relative change of growth rate amounts to less than 25 % and has a negligible influence on conductance. We anticipate the in-situ genetic algorithm optimization procedure to be of high relevance for new developments regarding binary or ternary systems prepared by focused electron or ion beam induced deposition.

show abstract

“…Interest in chemical processes induced by free electrons is motivated by emerging applications in technology, for example focused electron beam induced processing (FEBIP), 1 and the need to understand radiation-induced damage to living tissue. 2 An important primary electron-induced process leading to chemical change is dissociative electron attachment (DEA), an example being the dissociation of methanol, e À (E i ) + CH 3 OH -{CH 3 OH} À -CH 3 O À + H where E i is the energy of the incident electron and the intermediate short-lived anion is called a resonance.…”

Section: Introductionmentioning

confidence: 99%

A dramatic difference between the electron-driven dissociation of alcohols and ethers and its relation to Rydberg states

Ibănescu

Allan

2008

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

A difference was observed in the reactivity of alcohols and ethers toward free electrons. Whereas the lowest core-excited state of the negative ion-a 2 (n,3s 2 ) Feshbach resonance-of the alcohols readily dissociates by losing a hydrogen atom, ethers show no observable signal from this resonance. This difference in reactivity has a parallel in the anomalous shapes and energies of the parent states of the Feshbach resonances, the 1 (n,3s) Rydberg states of the neutral alcohols. We explained this anomaly using potential surfaces of the alcohols and ethers calculated using the TD-DFT method as a function of the dissociation coordinate. The lowest excited state of alcohols was found to be repulsive, whereas a barrier to dissociation was found in the ethers. Rydbergvalence mixing and avoided crossings are decisive in determining the shapes of the potential surfaces. It is concluded that the reactivities of alcohols and ethers toward free electrons are rationalized by assuming that the potential surfaces of the daughter Feshbach resonances closely follow those of the parent Rydberg states, i.e., the lowest Feshbach resonance is repulsive, but a barrier occurs in ethers. The potential surfaces of both the Rydberg states and the Feshbach resonances thus differ dramatically from the non-dissociative surface of the grandparent 2 (n À1 ) positive ions, despite the nominally non-bonding character of the Rydberg electrons.

show abstract

Resolution in focused electron- and ion-beam induced processing

Cited by 56 publications

References 25 publications

Electron-beam-induced deposition of 3-nm-half-pitch patterns on bulk Si

Electron-beam-induced deposition of 3-nm-half-pitch patterns on bulk Si

Identifying the crossover between growth regimes via in-situ conductance measurements in focused electron beam induced deposition

A dramatic difference between the electron-driven dissociation of alcohols and ethers and its relation to Rydberg states

Contact Info

Product

Resources

About