High Resolution Focused Ion Beam Research Articles

Production of a helium beam in a focused ion beam machine using an electron beam ion trap

Gallium liquid-metal ion sources that have been introduced in the late 1970s have allowed the development of a new class of micro- and nanofabrication tools collectively denominated as focused ion beam (FIB) machines. To investigate the potential of a helium beam in such a FIB instrument the authors have tested a room-temperature electron beam ion trap coupled with a high resolution FIB machine. In this letter they present their first results in target imaging using a helium beam with a resolution that allows to account for a beam diameter in the submicrometer range.

Focused ion beam sculpted membranes for nanoscience tooling

High resolution FIB offers nowadays the capability to sculpt matter at the nanometer scale. Using FIB to engrave membranes opens new emerging routes for nanoscience tooling. We propose here a way to fabricate tensile SiC membranes (with thicknesses adjustable between 10 and 100 nm), in order to drill them with high resolution focused ion beam, to obtain holes below 15 nm. Moreover, we show how we can, in some specific conditions, take advantage of the behavior of the irradiated matter (sputtering/redeposition processes) to reduce the size of the drilled hole below 10 nm. Eventually, we present two applications of these objects in biophysics and nanoscience tooling.

Analytical model of a gas phase field ionization source

High resolution focused ion beam technology is based on the use of field ionization sources. The most widely used source by far is the liquid metal ion source (LMIS) and most focused ion beam systems today employ it. The gas phase field ionization source (GFIS) is hardly employed today except in field ionization microscopy, but present day technology would allow its unique properties vis a vis the liquid metal ion source, including smaller virtual source size and energy spread, and the ability to produce ions from H, He, and heavier noble gases, to be exploited. If the GFIS is used as an ion source for a focusing column it would be useful to be able to calculate its emission properties (current versus voltage) as a function of emitter shape (a parameter not variable in a LMIS). Such a calculation had not been done precisely based on realistic emitter shapes. In this work, a theoretical description of the mechanism for ion production in a GFIS is presented. The comparison of the result with the experimental data for a H2–Ir GFIS is given, which shows reasonable agreement. With the present model, when used with the model for the optical properties of the GFIS (to be published), a focused ion beam (FIB) optical designer can make reasonable predictions about the properties of a GFIS-based FIB. Based on the modeling, we predict that a sub 1nm beam of He+ should be possible with ∼1pA current.

Exploration of the ultimate patterning potential achievable with focused ion beams

In this paper, we present our work aiming to explore the nano-structuring potential of high resolution focused ion beams (FIB), a technology capable of overcoming some basic limitations of current nano-fabrication techniques and to propose new patterning schemes for nanoscience. To demonstrate this, we present some of our recent results based on ion-induced local property modifications or localised damage injection. We first detail the very high resolution FIB system we have developed. Then FIB nano-fabrication experiments are presented and discussed. We show that stable artificial surface nano-defects can be created with very low ion dose. The properties of stable magnetic structures (dots and lines) fabricated on ultrathin magnetic films using extremely low surface ion dose (10 12–10 15 ions/cm 2) are presented. In a last example, we show that the promising direction of “bottom–up” or “organisation” processes can be envisaged with FIB. This can be achieved using defects capable of pinning the diffusion and of promoting organisation of nanometre-sized clusters (gold or cobalt–platinum) on a graphite crystalline surface.

Exploration of the ultimate patterning potential achievable with high resolution focused ion beams

Controlled and reproducible fabrication of nano-structured materials will be one of the main industrial challenges in the next few years. We have recently proposed exploitation of the nano-structuring potential of a high resolution Focused Ion Beam Tool, to overcome basic limitations of current nano-fabrication techniques. The aim of this article is to present some new routes for material patterning, which benefit from ion-induced local property modifications or damage. In the experiments we describe hereafter an ultra-sharp pencil of 30 keV gallium ions is used to tailor the characteristics of several materials at a scale of a few nanometres. The experimental results are then compared to simulations. First, we simulate the control of collisional defects generated in a thin magnetic layer under FIB irradiation. The results explain the stable magnetic structures we have obtained experimentally. This was achieved with a low surface ion dose (1012 to 1014 ions/cm2). In addition we have explored the promising direction of “Bottom-up” or “self-organization” processes using a FIB instrument. We have defined artificial surface defects. These defects created by the impact of an 8-nm FWHM probe were used to pin the diffusion and to organize nanometre-sized gold clusters on a graphite surface.

FIB technology applied to the improvement of the crystal quality of GaN and to the fabrication of organised arrays of quantum dots

In this paper we demonstrate the possibility of achieving selective epitaxy and epitaxial lateral overgrowth (ELO) using nanometric openings patterned with a focused ion beam (FIB). The test structure we used in this work consists of an AlN buffer layer on 6H–SiC with very high crystal quality close to pseudomorphism. This substrate is first covered with a thin (∼2 nm) silicon nitride mask deposited by CVD. Then a high resolution FIB was used to create regular openings with a range of sizes (lowest 100 nm) and organisation. Finally, GaN was grown on the structure by metal-organic vapour phase epitaxy (MOVPE). The relatively low ion dose (2.7 × 1016 ions/cm2) required to remove the surface layer allows reasonable patterning speeds (0.45 ms/pt) and minimises FIB-induced defect extension in the vicinity of the patterned GaN structures.

Corrosion Books: High Resolution Focused Ion Beams. By: Jon Orloff, Mark Utlaut, Lynwood Swanson

Materials and CorrosionVolume 55, Issue 4 p. 319-320 Corrosion Books Corrosion Books: High Resolution Focused Ion Beams. By: Jon Orloff, Mark Utlaut, Lynwood Swanson W. Österle, W. ÖsterleSearch for more papers by this author W. Österle, W. ÖsterleSearch for more papers by this author First published: 26 March 2004 https://doi.org/10.1002/maco.200490038AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume55, Issue4April 2004Pages 319-320 RelatedInformation

FIB technology applied to the improvement of the crystal quality of GaN and to the fabrication of organised arrays of quantum dots

In this paper we demonstrate the possibility of achieving selective epitaxy and epitaxial lateral overgrowth (ELO) using nanometric openings patterned with a focused ion beam (FIB). The test structure we used in this work consists of an AlN buffer layer on 6H–SiC with very high crystal quality close to pseudomorphism. This substrate is first covered with a thin (∼2 nm) silicon nitride mask deposited by CVD. Then a high resolution FIB was used to create regular openings with a range of sizes (lowest 100 nm) and organisation. Finally, GaN was grown on the structure by metal-organic vapour phase epitaxy (MOVPE). The relatively low ion dose (2.7 × 10 16 ions/cm 2) required to remove the surface layer allows reasonable patterning speeds (0.45 ms/pt) and minimises FIB-induced defect extension in the vicinity of the patterned GaN structures.

High Resolution Focused Ion Beams: FIB and Its Applications

<i>High Resolution Focused Ion Beams: FIB and Its Applications</i>

Focused ion beam created periodic structures on tapered optical fibers

High resolution focused ion beams have been used to create optical structures and to create high quality optical surfaces. We report here the use of Ga+ and B+ ion beams to produce gratings on optical fibers by micromachining and direct implantation, respectively. In both cases local periodic perturbations of the cladding refractive index were introduced in the reduced diameter (waist) region of biconically tapered single-mode optical fibers. By micromachining we produced short grooves perpendicular to the fiber axis and boron implantation gave a phase grating in the cladding. Both structures demonstrate a wavelength dependent throughput and are highly sensitive to the environment in the waist region, which makes them potentially applicable in sensors as well as in optical communication networks.

In-situ Er-doped GaN optical storage devices using high-resolution focused ion beam milling

High-density GaN:Er optical storage devices were fabricated with focused ion beam (FIB) milling techniques. In-situ Er-doped GaN films (1-1.5 μm thick) were grown on Si substrates. To write a bit, the GaN:Er film was selectively milled with a 30-keV Ga + FIB. Data retrieval is accomplished by upconversion emission at 535/556 nm upon 1-μm IR laser stimulation. Regions where the Er-doped GaN layer is completely removed (and do not emit) are defined as logic 0, while regions that are not milled (and do emit) are defined as logic 1. Data patterns with submicron bit size (or 100 Mb/cm 2 density) have been fabricated by FIB milling. Data written by this approach has a theoretical storage capacity approaching 10 Gbits/cm 2 .

Very high-resolution focused ion beam nanolithography improvement: A new three-dimensional patterning capability

We detail a novel three dimensional (3D) patterning capability for focused ion beam technology which uses, as a resist, a gold cluster compound Au55(PPh3)12Cl6. The high-resolution 3D morphology of the patterned structures is examined and electrical characterization analyses are carried out. Patterns having minimal lateral dimension about 30 nm and vertical resolution below 10 nm, are displayed using this method. Direct writing speeds up to 3.6 103 μm/s were reached.

Optimization of experimental operating parameters for very high resolution focused ion beam applications

We report an experimental procedure to optimize the current profile of a focused ion beam probe, with a special emphasis on high resolution applications. The optimized operating conditions are given for three specific cases: specimen thinning for electron microscopy, nanoetching, and nanolithography. We present high quality membranes for transmission electron microscopy, arrays of nanoholes with reproducible dimensions of 17 nm etched on a nickel membrane, and finally nanolithography operations with a 10 nm resolution. Due to the conventional design of our focused ion beam system, the operating conditions that we have established for each nanofabrication application, should be successfully applied to a wide variety of ion columns.

A new method for calculating the axial potential due to space charge in electrostatic optics

It is well known that the spherical aberration is positive for an axisymmetric electrostatic lens that is empty and free from space charge. However, a space charge profile can be tailored to introduce negative spherical aberration in such a lens. This could be useful for modern high-resolution focused ion beam systems. A new technique is described for calculating potentials and their derivatives and is used to calculate the trajectories of charge particles propagating in regions in which space charge is present. The charge density and potential are expanded in powers of r and z and the Poisson equation is solved term by term. The method has been implemented numerically for axisymmetric configurations. An illustrative example is presented.

High-resolution focused ion beams

The technology of high-resolution focused ion beams has advanced dramatically in the past 15 years as focusing systems have evolved from laboratory instruments producing minuscule current densities to high current density tools which have sparked an important new process: direct micromachining at the micrometer level. This development has been due primarily to the exploitation of field emission ion sources and in particular the liquid-metal ion source. Originally developed in the early 1960’s as a byproduct of the development of electrostatic rocket engines, the liquid-metal ion source was adapted for focused beam work in the late 1970’s, when it was demonstrated that submicrometer focused ion beams could be produced with current densities greater than 1 A cm−2. Ions can be produced with liquid-metal ion sources from elements including Al, As, Au, B, Be, Bi, Cs, Cu, Ga, Ge, Fe, In, Li, P, Pb, Pd, Si, Sn, and Zn. In the past decade, focused ion beam systems with liquid-metal ion sources have had a significant impact on the semiconductor industry as they were applied to new and greatly improved methods of failure analysis, as well as circuit repair and modification, in situ processing, and lithographic mask repair. This article discusses field emission ion sources, high-resolution ion focusing systems, and means for analyzing their performance. A number of technologically interesting and useful applications are also discussed.

High-resolution focused ion beam lithography

The resolution and alignment accuracy of FIB lithography is studied for making devices with 0.1 μm dimensions. 0.1-μm linewidth patterns are successfully fabricated by 260-keV Be++ FIB for both positive and negative resists. 50-nm linewidth Novolak based negative resist patterns are fabricated at 1.0×1012 ions/cm2 dose by 260-keV Be++ FIB. Dot patterns with 0.3 μm diam and high density (108/cm2) are written on a 1×1 cm area in a PMMA resist to demonstrate that FIB lithography can be applied to make practical devices with a large writing area. Moreover, mark detection and overlay accuracy are studied for marks covered with PMMA and CMS resists. Finally, FIB lithography is applied to fabricate 0.1-μm NMOS gate patterns. The overlay accuracy for hybrid exposure using FIB and an optical stepper is 0.2 μm at 2σ.

Design of a high resolution focused ion beam system using liquid metal ion source

We have made a Monte Carlo simulation to design a high resolution ion beam column with a liquid metal ion source (LMIS), which employs Koehler illumination. The use of Koehler illumination is one of the few ways to avoid the problem caused by the non‐Gaussian current density profile, which is due to the stochastic angular broadening of the ion beam near the source. Thus we can predict a 20 nm beam spot size with 1 nm edge sharpness and about 1 pA of ion current on the target plane at 100 keV beam energy with a Ga LMIS.

High-resolution focused ion beam lithography

Abstract The resolution of focused ion beam (FIB) lithography has been studied by proximity effect measurement and fine pattern fabrication. In proximity effect measurement, a 0.1 μm line pattern, according to the gap between square and line patterns, could be achieved. Moreover, 0.1 μm linewidth novolak based negative resist could be fabricated at 2X10 12 ions/cm 2 dose by 260 keV Be ++ FIB with 0.1 μm beam diameter. FIB lithography has also been applied to fabricating 0.1 μm NMOS gate patterns and X-ray masks.

High-resolution focused ion beam lithography

The resolution of focused ion beam (FIB) lithography has been studied by proximity effect measurement and fine pattern fabrication. In the proximity effect measurement, a 0.1 μm line pattern, according to the gap between square and line patterns, could be achieved. Moreover, 0.1 μm line and space poly(methylmethacrylate) patterns and 0.1 μm linewidth novolak based negative resist could be fabricated at 1×1013 and 2×1012 ions/cm2 dose by 260 keV Be++ FIB with 0.1 μm beam diameter, respectively.

Design of a 100 kV, high resolution focused ion beam column with a liquid metal ion source

A 100 kV ion beam column design is proposed which utilizes a liquid metal ion source and which employs Koehler illumination. The use of Koehler illumination appears to be the only way to avoid the problems caused by stochastic angular broadening of the ion beam at the source. The design goals are to achieve a 10 nm beam diameter with 2 nm edge resolution and approximately 1 pA of ion current at the target.