No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Improvements in the angular current density of inductively coupled plasma ion source for focused heavy ion beams
... The high current capability of ICP-FIB is due to high angular current density (J U ) of the ion beam extracted from ICP ion source. Experiments have shown that the ICP ion source is capable of producing ion beam of various gaseous elements with J U of three orders higher than that of various ion beams from LMIS [7]. Since milling rates are directly proportional to the available ion current in the focused spot, this newly developed ICP-FIB has superior performance in FIB applications that are beyond the capability of LMIS-FIB systems such as rapid milling of large volumes of material without contaminating the milled surfaces. ...
... The ICP-FIB system and characteristics of the ion source which is used to carry out the experiments in this article are presented in publications by the authors [5,7,17,18]. A two lens focusing column is employed to focus the beam at a working distance of about 2 mm. ...
... As a result, newly formed ions are accelerated away from a protrusion, and each atom acts as a point source, emitting a narrow ion beam (Fig. 2). Müller showed for the first time the possibility of forming an ion source whose minimum size is comparable with [5,6,[10][11][12][13][14][15][16], ( ) gas field ion sources [6][7][8][17][18][19][20][21][22], ( ) electrohydrodynamic sources [2][3][4]23], and ( ) sources with a magneto-optical trap [9]. Mg size of a single atom. ...
Описаны системы со сфокусированным ионным пучком, использующие газовые автоионные источники. В историческом контексте рассмотрены принципы работы таких источников и способы их формирования, эффективная область ионизации в которых определяется размерами одного атома. Описываемые системы имеют широкий спектр приложений как в области сканирующей ионной микроскопии в сочетании с различными аналитическими методами, так и в области модификации с высоким разрешением электрических, оптических, магнитных и других свойств материалов. Такая модификация основана на ионно-индуцированном изменении структуры материала и наиболее ярко выражена в кристаллических полупроводниках, сверхпроводниках и магнетиках.
A nanostructured interfacial layer with a graded structure is produced by hybrid high-power pulsed magnetron
sputtering–plasma immersion ion implantation and deposition (HPPMS–PIII&D) to improve adhesion of multifunctional
coatings. As a demonstration, a ceramic CrN film is prepared on stainless steel together with a Cr
interlayer. High-resolution transmission electron microscopy (HR-TEM) reveals the presence of a 40 nm thick
nanostructured interfacial layer between the Cr interlayer and substrate with gradually changing compositions,
and this layer which possesses a dense and pore/void free structure is responsible for the strong film adhesion.
The hybrid technology combines the benefits of both the HPPMS and PIII&D enabling fabrication of functional
films with the desired properties. The technique and fabrication strategy have many potential applications in
photovoltaics, energy storage, tribology, lubrication, aeronautics, and astronautics.
A high brightness inductively coupled plasma ion source based focused ion beam system is being developed. This system is intended to produce a low energy high current micron size beam of the heavier gaseous elements for high speed, micro milling applications. The basic aim of this development is to cater the needs of those applications which cannot be addressed by the conventional liquid metal ion source based FIB. A novel idea has been implemented in the design of the ion source where, a double plasma chamber is designed to initiate the plasma at low RF power. The plasma is first initiated by the capacitive coupling at low RF power in one chamber. This in turn triggers a strong, high density inductive discharge in another chamber, which is Faraday shielded by a thin slotted copper foil. The ion beam is extracted through 1 mm diameter aperture in the plasma electrode using a simple two electrode extraction system. The ion source has produced argon ion beam of 57 mA/cm2 with an angular current density of ∼10 mA/Sr at 160 W of RF power and 7kV of extraction voltage. In addition, the measurements show that the ion source has brightness of >8000 A/m2 Sr-1 V-1. The ion source is integrated with a two lens focusing column and beam currents from 2 nA to 2.5 μA were focused at a working distance of 5 mm. Measurements show that the currents in the range of 500 nA to 1 μA can be focused to spots having diameters in the range of 8–10 μm resulting in a current density of 450 mA/cm2 at the focused spot. In order to evaluate the milling rate of steel, experiments were carried out using 7 keV, 800 nA of argon ion beam. Preliminary results indicate that the milling rate of steel is >100 μm3/s.
A high brightness plasma ion source has been developed to address focused ion beam (FIB) applications not satisfied by the liquid metal ion source (LMIS) based FIB. The plasma FIB described here is capable of satisfying applications requiring high mill rates (≫100 μm3/s) with non-gallium ions and has demonstrated imaging capabilities with sub- 100-nm resolution. The virtual source size, angular intensity, mass spectra, and energy spread of the source have been determined with argon and xenon. This magnetically enhanced, inductively coupled plasma source has exhibited a reduced brightness (βr) of 5.4×103 A m-2 sr-1 V-1, with a full width half maximum axial energy spread (ΔE) of 10 eV when operated with argon. With xenon, βr=9.1×103 A m-2 sr-1 V-1 and ΔE=7 eV. With these source parameters, an optical column with sufficient demagnification is capable of forming a sub-25-nm spot size at 30 keV and 1 pA. The angular intensity of this source is nominally three orders of magnitude greater than a LMIS making the source more amenable to creating high current focused beams, in the regime where spherical aberration dominates the LMIS-FIB. The source has been operated on a two lens ion column and has demonstrated a current density that exceeds that of the LMIS-FI- - B for current greater than 50 nA. Source lifetime and current stability are excellent with inert and reactive gases. Additionally, it should be possible to improve both the brightness and energy spread of this source, such that the (βr/ΔE2) figure-of-merit could be within an order of magnitude of a LMIS.
A compact, high brightness 13.56 MHz inductively coupled plasma ion source without any axial or radial multicusp magnetic fields is designed for the production of a focused ion beam. Argon ion current of density more than 30 mA/cm(2) at 4 kV potential is extracted from this ion source and is characterized by measuring the ion energy spread and brightness. Ion energy spread is measured by a variable-focusing retarding field energy analyzer that minimizes the errors due t divergence of ion beam inside the analyzer. Brightness of the ion beam is determined from the emittance measured by a fully automated and locally developed electrostatic sweep scanner. By optimizing various
ion source parameters such as RF power, gas pressure and Faraday shield, ion beams with energy spread of less than 5 eV and brightness of 7100 Am(-2)sr(-1)eV(-1) have been produced. Here, we briefly report the details of the ion source, measurement and optimization of energy spread and brightness of the ion beam. (C) 2010 Elsevier B.V. All rights reserved.
Focused ion beam characteristics, measured by using PMMA resist exposures, show significant improvement of the previously reported results for hydrogen ion beams. A beam current density of ≫50 mA cm-2 at 6–7 keV has been obtained over a spot size of 2.3 μm, estimated from the full width at half maximum of the intensity distribution. A single Einzel lens with magnification of about 0.1 was used. A target current density of ≫1 A/cm2 can be achieved with this beam for a lens system with overall magnification of ∼0.01. In experiments with Ar, both the discharge current and extracted beam current increased by more than a factor of 2 when the discharge cell length was increased by about 25% with respect to the nominal cell length for operation with H. Ar ion beams were extracted with an angular beam intensity of ≫5 mA sr-1, brightness (90% beam) of ∼103 A sr-1 cm-2 at 10 keV, and energy spread of ∼4.5 eV. Greatly improved beam characteristics, with brightness ≫104 A sr-1 cm-2, are expected by optimization of the source for Ar beams. © 1999 American Vacuum Society.
The first edition of this title has become a well-known reference book
on ion sources. The field is evolving constantly and rapidly, calling
for a new, up-to-date version of the book. In the second edition of this
significant title, editor Ian Brown, himself an authority in the field,
compiles yet again articles written by renowned experts covering various
aspects of ion source physics and technology. The book contains full
chapters on the plasma physics of ion sources, ion beam formation, beam
transport, computer modeling, and treats many different specific kinds
of ion sources in sufficient detail to serve as a valuable reference
text.
Experimental results are given for the perveance and beam divergence of a single aperture three electrode extraction system using helium ions at energies between 10 and 30 keV. The aperture radii, the electrode thicknesses, and the spacings were varied and from the results a preferred design was obtained for use in a multiaperture array. The most critical parameter was the ratio (S) of the radius of the first aperture to the distance between the first and second electrodes, the highest current density being obtained at values of this ratio less than 0.5. The optimum beam divergence observed corresponded to a Gaussian beam profile with a width (ω) of ± 1.2° at 2 m from the source. The measured perveance at small values of S and at minimum ω lay between 75% and 90% of the value predicted on the basis of a simple model using the Langmuir‐Blodgett formula for the spherical diode.
The sub-micron ion beam system has been developed using the duoplasmatron-type ion source and special lenses with the double functions of the beam focusing and acceleration. The beam width was about for about 30 keV hydrogen ions, though the value was slightly larger than the one estimated from the beam transport calculation. The slow drifting of the beam spot position within was observed during the experimental time of about 10 min. The improvements by means of introducing the beam injection system enabled us to achieve the beam width of and a slight drift of the beam spot within .
The ion energy distribution of inductively coupled plasma ion source for focused ion beam application is measured using a four grid retarding field energy analyzer. Without using any Faraday shield, ion energy spread is found to be 50 eV or more. Moreover, the ion energy distribution is found to have double peaks showing that the power coupling to the plasma is not purely inductive, but a strong parasitic capacitive coupling is also present. By optimizing the various source parameters and Faraday shield, ion energy distribution having a single peak, well separated from zero energy and with ion energy spread of 4 eV is achieved. A novel plasma chamber, with proper Faraday shield is designed to ignite the plasma at low RF powers which otherwise would require 300-400 W of RF power. Optimization of various parameters of the ion source to achieve ions with very low energy spread and the experimental results are presented in this article. (C) 2010 Elsevier Ltd. All rights reserved.
Electrostatic lens systems
- Dwo Heddle
Heddle DWO. Electrostatic lens systems. 2nd ed. Bristol: Institute of Physics
Publishing; 2000.
- N S Smith
- W P Skoczylas
- S M Kellogg
- D E Kinion
- P P Tesch
- O Sutherland
Smith NS, Skoczylas WP, Kellogg SM, Kinion DE, Tesch PP, Sutherland O, et al.
J Vac Sci Technol B 2006;24:2902e6.
- P Y Nabhiraj
- R Menon
- Mohan Rao
- G Mohan
- S Bhandari
Nabhiraj PY, Menon R, Mohan Rao G, Mohan S, Bhandari RK. Vacuum 2010;85:
344e8.
- P Y Nabhiraj
- R Menon
- R K Bhandari
Nabhiraj PY, Menon R, Bhandari RK. J Vac Sci Technol B 2011;29:051604-1e
051604-6.
- Jr Coupland
- Ts Green
- Dp Hammond
- Ac Riviere
Coupland JR, Green TS, Hammond DP, Riviere AC. Rev Sci Instrum 1973;44:
1258e70.
- P Y Nabhiraj
- R Menon
- Mohan Rao
- G Mohan
- S Bhandari
Nabhiraj PY, Menon R, Mohan Rao G, Mohan S, Bhandari RK. Nucl Instrum Meth
B 2010;621:57e61.
Bristol: Institute of Physics Publishing
- Dwo Heddle
Heddle DWO. Electrostatic lens systems. 2nd ed. Bristol: Institute of Physics
Publishing; 2000.