Lateral templating of self-organized ripple morphologies during focused ion beam milling of Ge

Ichim, Stefan; Aziz, Michael J.

doi:10.1116/1.1897711

Cited by 25 publications

(20 citation statements)

References 16 publications

(2 reference statements)

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“…Recently, Datta, Wu, and Wang used focused ion-beam microscopy to induce and observe ripple formation on diamond but could not detect any movement [13]. Habenicht et al observed moving ripples on Si [14], but the bombarded area was so small that its boundaries determined ripple development [15].…”

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confidence: 99%

Propulsion of Ripples on Glass by Ion Bombardment

Alkemade

2006

Phys. Rev. Lett.

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The propulsion of surface ripples on SiO 2 by an ion beam was investigated by in situ electron microscopy. The observed propagation of the ripples contradicts existing models for ion-beam-induced ripple development. A new model based on the Navier-Stokes relations for viscous flow in a thin layer is introduced. It includes inhomogeneous viscous flow, driven by spatial variations in the deposition of the energy of the ion beam. The model explains the observed reversed propagation. The hitherto unknown propulsion mechanism is important for understanding nanoscale pattern formation by ion bombardment. DOI: 10.1103/PhysRevLett.96.107602 PACS numbers: 79.20.Rf, 61.80.Az, 68.35.Ct, 81.16.Rf Modification of surfaces is a widely explored and technologically highly relevant field of research. Surfaces bombarded by a beam of ions erode, but they may also develop specific nanoscale geometrical patterns [1]. These patterns have been studied intensively because they reveal details in the interaction of energetic particles with matter and because they have implications for ion-beam sputter erosion and deposition [2]. Recently, the formation of surface patterns by ion bombardment received appreciation as templates for the growth of low-dimensional nanostructures [3]. Various theories describe aspects of beaminduced pattern formation. Although they are widely applied, not all relevant processes are understood, not even qualitatively.A very common pattern is a series of ripples that can form under oblique incidence of kilo-electron-volt ions. Sigmund showed that the dependence of the material's erosion rate on the curvature of the surface leads to the growth of surface irregularities [4]. Bradley and Harper (BH) used Sigmund's model to explain the appearance of ripple patterns with a distinct wavelength [5]: Ripple formation is the result of a competition between curvaturedependent roughening and smoothing by thermal surface diffusion. The original BH model has been extended to include smoothening by beam-enhanced surface diffusion [6] and beam-enhanced viscous flow [7]. Carter suggested that viscous relaxation of a thin surface layer, compressively stressed by the ion bombardment, causes ripple formation [8], and Rudy and Smirnov used the NavierStokes relations to describe ion-beam-enhanced viscous flow [9]. Recently, Umbach, Headrick, and Chang showed that the enhanced viscous flow is limited to the ion penetration layer [10]. A common factor of all models is that only the ripples' growth rate has been tested experimentally. In contrast, the notion that ripples propagate across the surface is rarely outspoken [5,11] but always implicitly assumed. The overall surface erosion velocity is ÿ 0 ÿY f cos =n. Here Y is the number of removed atoms per incident ion, the angle between the ion beam and the surface normal, f the ion flux, and n the atomic density of the solid; the minus sign reflects the recession of the surface. Because of the increase of Y with up to 75 , the slopes that face the incident ion beam (the up slopes; se...

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confidence: 99%

Propulsion of Ripples on Glass by Ion Bombardment

Alkemade

2006

Phys. Rev. Lett.

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“…This idea is given additional support by the experimental results of Ichim and Aziz. 8 Although we do find that highly regular ripples form for certain ranges of parameters, other types of patterns also emerge.…”

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confidence: 90%

“…Limited progress has been made in reducing the number of defects in surface ripples-for example, experiments have shown that few defects form near the boundary of a region subjected to OIIB. 8 Similarly, if the surface is pre-patterned with parallel trenches with a width equal to a few times the ripple wavelength, the ripples that form in the trenches tend to align with the trench walls, and the number of defects in the ripple patterns is small.…”

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Highly ordered nanoscale patterns produced by masked ion bombardment of a moving solid surface

Gelfand

Bradley

2012

Phys. Rev. B

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“…The scan direction of the FIB can be irrelevant to the ripple orientation [4][5][6][7][8][9], with a caveat that the scan pattern is a wellcontrolled, overlapping-digital pattern. Even boundary conditions can be the same for FIB or static beams [4][5][6], however FIB generally creates 3-D geometries, and boundary conditions such as aspect ratio are paramount to FIB processing [7][8]. As we etch deeper, the yield drops.…”

Section: Introductionmentioning

confidence: 99%

“…Modulations can depend on many parameters [2][3][4][5][6][7][8][9][10]: intrinsic to the ion beam (eV, angle, species, dose); intrinsic to the sample (species, crystallography, grain orientations, boundary conditions such as pre-patterned 3-dimensional geometries [4][5][6] or interfaces and crater sidewalls [7][8]11]); and/or extrinsic (temperature, chemical enhancers). Ripples can develop independent of whether a big static ion beam or a Focused Ion Beam is used [3][4][5][6][7]. The scan direction of the FIB can be irrelevant to the ripple orientation [4][5][6][7][8][9], with a caveat that the scan pattern is a wellcontrolled, overlapping-digital pattern.…”

Section: Introductionmentioning

confidence: 99%

Ion Beam Induced Surface Modulations from Nano to Pico: Optimizing Deposition During Erosion and Erosion During Deposition

MoberlyChan

Schalek

2007

MRS Proc.

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Ion beams of sufficient energy to erode a surface can lead to surface modulations that depend on the ion beam, the material surface it impinges, and extrinsic parameters such as temperature and geometric boundary conditions. Focused Ion Beam technology both enables site-specific placement of these modulations and expedites research through fast, high dose and small efficient use of material. The DualBeam (FIB/SEM) enables in situ metrology, with movies observing ripple formation, wave motion, and the influence of line defects. Nanostructures (ripples of >400nm wavelength to dots spaced <40nm) naturally grow from atomically flat surfaces during erosion, however, a steady state size may or may not be achieved as a consequence of numerous controlled parameters: temperature, angle, energy, crystallography. Geometric factors, which can be easily invoked using a FIB, enable a controlled component of deposition (and/or redeposition) to occur during erosion, and conversely allow a component of etching to be incurred during (ion-beam assisted) deposition. High angles of ion beam inclination commonly lead to "rougher" surfaces, however, the extreme case of 90.0° etching enables deposition of organized structures 1000 times smaller than the aforementioned, video-recorded nanostructures. Orientation and position of these picostructures (naturally quantized by their atomic spacings) may be controlled by the same parameters as for nanostructures (e.g. ion inclination and imposed boundary conditions, which are flexibly regulated by FIB). Judicious control of angles during FIB-CVD growth stimulates erosion with directionality that produces surface modulations akin to those observed for sputtering. Just as a diamond surface roughens from 1-D ripples to 2-D steps with increasing angle of ion sputtering, so do ripples and steps appear on carbon-grown surfaces with increase in angle of FIB-CVD. Ion beam processing has been a stalwart of the microelectronics industry, is now a vital tool for research of self-organizing nanostructures, and promises to be a focus for future picotechnology.

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Lateral templating of self-organized ripple morphologies during focused ion beam milling of Ge

Cited by 25 publications

References 16 publications

Propulsion of Ripples on Glass by Ion Bombardment

Propulsion of Ripples on Glass by Ion Bombardment

Highly ordered nanoscale patterns produced by masked ion bombardment of a moving solid surface

Ion Beam Induced Surface Modulations from Nano to Pico: Optimizing Deposition During Erosion and Erosion During Deposition

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