The FLIG® 5 is floating low energy ion beam system designed primarily for use on SIMS depth profiling instruments. It has a floating column which transports O2+ ions at relatively high energy prior to deceleration in the final lens. This enables it to deliver a probe of high current density at beam energies as low as 200 eV. This low energy performance makes the FLIG® 5 a powerful tool for shallow depth profiling.
The requirement for high depth resolution dynamic SIMS arises from the reduction in device size in the semiconductor industry. With the use of low implantation energies and new technology dependent on delta-doping and sharp interfaces, it is increasingly important to have access to depth profiling techniques which can quantify these structures both accurately and reproducibly.
When profiling with energetic oxygen beams, the kinetic energy of the incident particles is transferred to the near surface region of the sample, creating an altered layer in which atomic mixing has occurred. The depth of this layer is approximately 4nm per keV for an O2+ beam, and this imposes an absolute limit on depth resolution. Hence, it is necessary to use energies well below 1keV for profiling of shallow junctions.
Another important factor in the analysis of shallow implants is the transient region which occurs at the surface and at matrix interfaces. At the beginning of a shallow profile, the ion and sputter yields vary rapidly as probe atoms are incorporated into the analysed surface, and the surface chemistry changes. Similar effects occur at matrix interfaces. Whilst this behaviour persistes, the profile depth profile is not quantifiable, and any features lying within the transient will be distorted. The thickness of the region, and hence, the amount of lost information, can be reduced by using low impact energies.
The Principle of the Floating Ion Gun
In a conventional ion gun, ions are transported through almost the whole ion-optical column at an energy determined by the anode voltage. Thus, to attain a 250 eV impact energy (on a grounded sample) the anode must be set to 250 V and the beam travels through the column at this energy. At such low energy, space charge effects and aberrations of the wide beam seriously limit the final intensity of the probe and impair the probe shape.
In the floating ion gun, almost all of the column is floated to a negative potential and the beam is accelerated to a more viable transport energy between the extraction region and the final lens. Inside the final lens, the beam is decelerated to the desired impact energy. Thus, for a 250 eV impact energy, the anode is set to 250 V and the float could be -3 kV giving a transport energy of 3.25 keV. This provides a signicant reduction in beam aberrations. In the FLIG, the Wien filter electrostatic plates and alignment units (including a bend to reject neutrals) are all referenced to the float voltage.
High Erosion Rate, Even at Low Energy
Shallow junction profiling requires the use of a low energy primary beam in order to minimise the effects of atomic mixing induced by the beam. As sputter yield reduces with lower energies, it is vital that the low energy probe has a high current density. Figure 1 shows characteristic plots of probe size versus beam current for the FLIG 5.
The FLIG 5’s high brightness duoplasmatron source and floating column optics deliver exceptional probe inten-sity, in comparison with conventional systems, facili-tating low energy profiling with acceptable erosion rates.
High Depth Resolution and Dynamic Range
To attain high depth resolution without sacrificing erosion rate, the bottom of the analysis crater must re-main flat through the profile. A good probe shape, with minimum aberration tails, is essential to minimise cur-vature at the sides of the crater. Reducing the extent of this curvature enhances depth resolution and dynamic range, as well as allowing the use of smaller scan fields and hence shorter analysis time.
Figure 1. Current vs spot size for the FLIG® 5.
The FLIG’s floating column transports the beam through most of the optics at high energy (generally between 2.5keV and 5keV). This greatly assists in reducing beam spreading in the column and concomi-tant aberrations in the probe. The result is sub-nanometer depth resolution at low energy, with profiles showing high dynamic range at all energies.
The depth resolution capability is demonstrated in Figure 2, which shows profiles of a Si-Ge superlattice. Grown by MBE, this structure has alternating 1nm layers of Si and Ge. The low energy profile shows a 45% valley between Ge peaks 14 and 15, showing the feature to be easily resolved.
Figure 2. Depth profiles of SiGe lattice
A remarkable feature is the apparent increase in resolution with depth in the low energy profile. A cross-sectional TEM image of the sample revealed that the upper layers were buckled, causing the lower resolution of the top layers.
Ease of Operation
Control of the voltage settings in the FLIG is greatly sim-plified by the use of a computer software interface. This allows many useful features to be built into soft-ware, the most valuable being the facility to save complete sets of operating voltages. Critical control voltages such as extraction and alignment are refer-enced to other supplies rather than ground to simplify tuning of the column.
The system is ready for use with automated systems which can command a change of preset conditions, when required, using ascii commands.
The IOG 30D is a high-brightness focused ion beam system for contaminant free micro-machining or analysis of small areas. It uses a duoplasmatron ion source and two-lens optical column to produce a high-brightness, low-aberration spot. The source may run on pure argon (or other noble gases), nitrogen, or oxygen, and a mass filter is included in the column to separate beams of different mass/charge species. A selection of 5 apertures allows a wide current range. A gate valve in the column allows the source to be serviced without venting of the whole column.
The IOG 30D is designed for retrofitting to vacuum chambers of electron microscopes or SIMS instruments. It mounts via an NW63CF flange, either directly onto an instrument CF flange with clearance boltholes, or via a spacer to adapt to an O-ring flange. The column includes a 2° bend to reject any neutrals in the beam. So, the lower column projects into the instrument chamber off centre by ~6 mm, and angles towards the port axis such that it intersects the sample on the centreline.
The flange to end of column distance can be adapted at the time of manufacture, and can be set between 188 mm and 210 mm. The distance from the end of the column to the sample should ideally be between 18 and 25 mm.
The upper chamber of the ion column requires differential pumping, ideally via a 60 ls-1 turbo pump.
The gas supply must be a high purity (99.999%) with low water content for good performance. This is to be connected to a 6 mm stainless steel tube at the source. Noble gases can be switched off when not in use, Oxygen should be run continuously.
The IOG 30D includes a 6U high voltage power supply for installation in a standard 19 inch rack. This provides the arc supply for the Duoplasmatron and all high voltage and static deflector supplies for the column.
Control is via a software interface, provided on cd for pc installation.
A suitable beam scanning system should be connected to the column. A system for secondary electron detection and imaging is also needed. Ionoptika offers these or we can advise on connections for alternative systems.
Figure 1. SED imaging with 30 keV helium beam, 50pA, achieving 100 nm spatial resolution. Image courtesy of National Institute for Materials Science, Japan.
The IOG 25GA is a high performance 25 kV gallium ion beam system, designed for use in micromachining and imaging SIMS applications. It offers a wide current range with fine probe capability and DC or pulsed operation. A PC control interface allows easy setup and monitoring of the system.
The IOG 25GA delivers a focused beam with beam energy of up to 25 keV. The wide current range enables the system to be used in a variety of applications from high precision direct write to large area quadrupole SIMS. In the lower current range, spatial resolution down to 50nm is achievable, subject to platform stability.
The assembly is configured for ease of installation as an instrument upgrade, with feedthroughs clustered together to allow minimum mechanical interference. A range of versions is available to accommodate different flange sizes or port lengths, and the column can be conventionally pumped or differentially pumped.
The assembly consists of a gallium liquid metal ion source and a high precision two-lens optics assembly, illustrated in figure 1. There are manual and motorised options for aperture selection.
The IOG 25GA can be operated in collimated mode or in crossover mode, in which an intermediate field image is produced between the lenses. In this mode it can be set up for minimum motion blanking for TOF-SIMS.
The crossover mode can also be used in DC operation as a variable probe current mode, controlling the beam current by moving the intermediate image along the optical axis.
The IOG 25GA power supply unit is a 6U rack-mountable 19 inch box. This provides all the high voltage and static deflector voltages required by the system. A sophisticated control software package is included; this can be installed on a PC running Windows 7 or higher.
Schematic of IOG25GA Ion Optics
The IOG 25 gives excellent spatial resolution throughout its current range, from micron performance at over 10 nA of beam current to below 50 nm in low current mode. It should be noted that the small spot performance requires a stable instrument platform with suitable isolation from vibration.
Figure 2 is a secondary electron image of a 12.5 micron copper grid, showing features below 50 nm across at a 25 mm working distance. A larger scan field can be achieved with a ± 200 V scan at greater working distances, as shown in Figure 3.
Secondary electron image of 12.5 micron repeat grid
A chamber vacuum of < 1×10-8 mbar is required. If the system does not achieve this, a differentially pumped version should be considered.
Field of view of IOG 25GA is > 2.5 x 2.5 mm
The IOG 25GA has a compact design, to facilitate its installation on a range of instruments. The envelope of the gun can be varied to meet individual user needs, and the following versions are available:
Standard version (see figure).
Extended nose length, to customer specification.
NW100CF, and other flanged versions.
Differentially pumped version.
Version with bellows for adjusting the length and angle of the gun.
Key dimensions of the IOG 25GA
The following items are also available from Ionoptika, for use with the IOG 25GA:
The IOG 25AU is a 25 kV high performance liquid metal ion beam system designed to provide a range of gold and gold-cluster ion beams for SIMS applications. It offers a wide current range with fine probe capability and DC or pulsed operation. Digital control allows easy setup of the gun and a provision for remote control is included.
Gold-germanium liquid metal ion source.
Resolving power of < 150 nm.
Wien filter for selection of different species
Mass filtered beam available in both DC and pulsed mode
The most useful species that can be selected by the mass filter are as follows:
% of Beam Current
The use of a gold cluster ion beam gives a significant improvement in ion yields compared with lower mass primary ions. The figure below shows that the gold and gold cluster beams show a progressive increase in yield, all being superior to a gallium primary beam. In the 1000-2500 mass range, Au3+ shows 75 times the yield from gallium.
Absolute ion yields from a thin film of PS2000, a low molecular weight polystrene
The next figure illustrates the imaging capabilities of the IOG 25AU, with the four prevalent gold cluster ions. The Au++ shows particularly high spatial resolution of the 12.5 micron mesh.
Secondary electron images of a 12.5 micron repeat copper grid.
The ion gun consists of a gold-alloy liquid metal ion source and a high precision two-lens optics assembly. This assembly includes:
stigmation and alignment units
deflection plates for blanking the beam
pulse bunching units
The IOG 25AU can be set up for minimum motion blanking for TOF-SIMS by placing an intermediate field image is between the pulsing plates. This crossover mode can also be used in d.c. operation as a variable probe current mode – controlling the beam current by moving the intermediate image along the optical axis.
Electronics & Control
The ion gun is driven by a 6U, 19 inch high-voltage power supply unit. Control is via a PC user interface, with communication between computer and power supply via a serial interface. The control software is available as an installable package or ready installed on a PC. The software comes with a range of useful features including the option of running either voltage or current control, wobble function, panel lock and saving settings.
The high voltage unit provides the following supplies:
Lens 1 Voltage
Lens 2 Voltage
Stigmation (amplitude and angle)
The IOG 25AU has a compact design, to facilitate its installation as an instrument upgrade. The envelope of the gun can be varied to meet individual user needs, and the following versions are available:
Standard version: NW63CF with 170mm long nose
Extended version (length to customer specification)
NW100CF, or NW150CF flanged versions
Differentially pumped versions
The following items are also available from Ionoptika, for use with the IOG 25AU:
The use of cluster beams for sputtering organic and polymer materials is now well established, with the high sputter rates and low damage levels achieved making their use as sputtering systems widespread in SIMS and XPS.
For use as a primary ion source for SIMS analysis, these cluster beams were limited, as they had large spot sizes, and poor ionization levels. The GCIB 40, operating at 40 keV beam energy, has addressed these issues, and has two clear advantages over working with lower energy beams: higher ionization yields, and improved spatial resolution.
Higher Ionization Yields
In organic analysis, the material being bombarded is often damaged by the ion beam, resulting in loss of molecular signal. With a GCIB, the induced damage is reduced so that the material can be analysed and depth profiled. But at lower beam energies the secondary ion yield with the GCIB is not very high, so signals can be low. Operating at higher energies results in a much higher yield of secondary ions, while still maintaining the low damage characteristic.
Using a sample of Irganox 1010, with equal primary ion dose, figure 1(a) shows results for signal intensity with four different cluster beam energies. It shows a very strong trend for signal to increase with energy.
The figure below shows that fragmentation by the higher energy beam is mostly on a par, or slightly better, than the lower energy beams.
Signal Enhancement with no increase in fragmentation. (a) normalised signal intensity for molecular and significant fragment signals from Irganox 1010, showing much higher ion yields for higher beam energy. (b) normalised signal ratios, comparing levels of fragmentation for four different beam energies. Data courtesy of Dr J. Fletcher, University of Gothenburg.
Greater Resolving Power
The figure below illustrates the enhanced spot size performance with the 40 keV beam. The first image, 2(a), shows an overlay of four masses found in a section of human hair ends supported in gelatine. The image size is 256 × 256 μm2, 128 x 128 pixels, positive ion mode. the primary ion dose density was approximately 1e13 ions/cm2. Figure 2(b) has image size 90 x 90 μm2 with 128 x 128 pixels and (c) shows a line scan plot taken from image (b). It indicates a spatial resolution of less than 3 microns.
ToF-SIMS imaging of human hair. (a) overlay, red: m/z 318.16, m/z 333.19; green: m/z 284.27, m/z 324.28; blue: m/z 331.17, m/z 845.52 (d18:1/23:0 di-hydro-sphingomyelin); white: m/z 114.88 (In). 2(b) total ion image and (c) a line scan across an edge of the hair in (b). Data courtesy of Dr J. Fletcher, University of Gothenburg.
The GCIB 40 system comprises:
Ion source, comprising cluster generation and ionization chambers.
Ion optical column, including a mass filter.
Power supplies to drive the ion source and column.
Source pumping system.
Gas clusters are formed by adiabatic expansion and then ionised by electron bombardment.
The cluster ions are accelerated into an ion column which contains a Wien filter, 5 selectable apertures (for selection of current and spot size ranges), a gate valve (for isolation of source from instrument during maintenance), a pulsing unit, a bend to remove neutrals, scan plates and a final focussing lens.
The Wien filter selects single cluster sizes for the small clusters; for the larger clusters (~Ar100 upwards) the beam consists of a mass distribution around the
nominal cluster size.
The GCIB 40, with its high-energy gas cluster analysis beam, offers better signal with low damage in organic SIMS analysis, with < 3 microns spatial resolution.
The GCIB SM is a 70 kV sub-micron gas cluster ion beam designed for high-resolution imaging SIMS of organic samples without the fragmentation typically associated with ion beam bombardment. Combined with the J105 SIMS, the GCIB SM extends the available mass range to > 2500 Da with sub-micron resolving power.
The benefits of gas cluster beams for use in organic SIMS is now well established – high-mass clusters are highly efficient at sputtering organic and polymeric materials, producing intact molecular and high-mass fragment ions. Until now, however, spatial resolution of these beams was limited to several microns. Incorporated onto the J105 SIMS, the GCIB SM focuses a 70 keV beam of gas clusters—up to CO2 (10k)—into a spot as small as 1 μm, revealing even more from your samples.
High-resolution Gas Cluster SIMS. (left) Total SIMS image of a pine-needle cross section obtained on the J105 SIMS at 1.5 μm per pixel, running a 50 kV CO2(5k)+ beam. (right) SIMS mage of untreated hippocampus tissue with various masses overlaid: blue = GM1 (1572.9 m/z), yellow = GM1 (1544.8 m/z), green = ST (806.5 m/z), taken at 2 μm per pixel with a 30 kV CO2(3k)+ beam. Data courtesy of Dr Hua Tian, Pennsylvania State University.
Cluster beams, where the energy per nucleon is quite low, are extremely effective at sputtering soft materials such as organic tissue and polymers. Unlike polyatomic beams such as Bi3+ or Au3+, which cause significant fragmentation of organic molecules both in the surface and sub-surface regions, gas cluster beams produce very little fragmentation, and cause almost no sub-surface damage, enabling depth profiling through organic tissue without loss of fidelity.
Single Cell Depth Profiling. Overlay image showing lipid (cyan) and adenine (magenta) signals inside individual HeLa cells, taken at 1 μm per pixel with a 50 keV CO2(5k)+ beam on the J105 SIMS. This image was taken as part of a series during which the top surface of the cells was gradually ethced away, revealing the nuclear material within. Data courtesy of Dr Hua Tian, Pennsylvania State University.
Combining high-spatial resolution with low-damage sputtering of organics, the GCIB SM provides users unparalleled access to details previously hidden within their samples, or which required multiple techniques to reveal. This latest advancement in gas cluster beam technology bridges the gap between conventional SIMS technology—high spatial resolution, destructive—and other imaging MS techniques such as MALDI (matrix assisted laser desorption ionization) and DESI (desorption electrospray ionization)—low spatial-resolution, non-destructive.
Resolving Power. Secondary electron image of a metallic mesh obtained using a 70 keV CO2(8k) beam, showing 1 μm spot size. Data courtesy of Dr Hua Tian, Pennsylvania State University.
The GCIB SM system comprises:
Ion source, comprising cluster generation and ionization chambers
Ion optical column, including a mass filter.
Power supplies to drive the ion source and column.
Source pumping system.
Schematic layout of the GCIB-SM
20 kV to 70 kV
Selectable Cluster Sizes:
CO2(1) to CO2(10k)
Minimum Spot Size:
< 1 μm
CO2(10k) Maximum Current
> 1 nA
https://i2.wp.com/www.ionoptika.com/wp-content/uploads/2018/02/GCIB-SM_thumb.jpg?fit=990%2C800&ssl=1800990webmasterhttps://www.ionoptika.com/wp-content/uploads/2018/06/IO_logo_black_700x322.pngwebmaster2018-02-19 09:46:372018-02-22 12:44:09GCIB SM
The GCIB 10S is a 10 keV argon gas cluster ion beam system, designed for easy installation on a wide range of surface analysis instruments. It provides an economical means of upgrading XPS, SIMS, or other systems to use cluster beam sputtering for sample cleaning or depth profile analysis.
Cluster ion beams enable depth profiling analysis of polymers with minimal loss of chemical information due to ion beam damage. This is crucial in analysis of modern multi-layer structures, such as in OLED and OPV devices, but also shows a marked improvement in analysis of well-established materials.
Ions are generated in the ion source by a 2-stage process. Firstly, argon clusters are formed by the adiabatic expansion of argon gas through a nozzle, starting at high pressure and passing into a region which is pumped to low vacuum. Then, passing through skimmer apertures into the next vacuum stage, the clusters enter an ionization chamber and they are ionized by electron bombardment. The cluster ions are accelerated into an ion column which contains a Wien filter, a gate valve (for isolating the source from an instrument during maintenance), a bend to remove neutrals, scan plates and a final focussing lens. The Wien filter can select single cluster sizes for the small clusters; for the larger clusters the beam consists of a mass distribution around the nominal cluster size.
The GCIB 10S system comprises:
Ion source, with cluster generation and ionization chambers
Ion optical column, including a mass filter
Two turbo pumps, two backing pumps, gauge, pipework, and controllers
Power supply units and interface software to drive the ion source and column
The GCIB 10S can be installed on a wide range of instruments, the main requirement being a NW63CF flange aiming at the sample. A selection of supports are available to relieve strain on the instrument flange where necessary. Installation packages already developed include ones for:
The PUL 03 is a 10 nanosecond, 400 volt pulser, primarily designed for use with Ionoptika ion beam systems to provide a fast pulsed beam. However, it may also be used with other systems that have suitable termination.
The PUL 03 comprises a control box, a 24 V dc power supply and an amplifier that connects directly to the ion column feedthrough . The pulser is controlled by means of a touch pad on the top of the unit. Mode of operation, voltage, and pulse width are selectable. It is designed to drive an open circuit load of 4 to 10 pF capacitance. It is not intended to run into any resistive load or short circuit of less then 10 Mohm.
The Pulser has 4 modes of operation: 1. Volts to Ground Mode
This is the main mode of operation – the pulser output normally sits at the set voltage (set between +10 V and +400 V). When triggered, the output drops to zero for the set duration, then returns to the set voltage. It requires a trigger pulse of 0 to 5 volts, remaining at 5 volts for longer then the duration of the output pulse. It also needs to be at the set voltage for a minimum of 100 nsec prior to the rising edge that it triggers on. The minimum pulse width is about 10 nsec. 2. Ground to Volts Mode
The second mode of operation is with the pulser output at ground, pulsing to the set voltage when triggered then back to ground after the set time. Note that this mode has a minimum pulse width of about 100 nsec. 3. Follow Mode
This sets the output high when the input is high, and low when it is low (or this can be inverted). 4. Internal Clock Mode
This allows you to set a frequency for it to run at – e.g. 10 kHz – and it will then run at that speed, with pulses as set by mode 1 or 2. There is a maximum frequency of 10kHz.
The PUL 03 has a separate 24 V dc psu, that runs from a universal mains input. This connects to the control unit in the socket on the right hand side of the box.
There is a BNC trigger input. This requires a 0 to 5 volt pulse, of duration longer than the required output pulse. The output pulse occurs 194 ns after the trigger. The trigger pulse needs to be able to drive a 50 ohm load.
There is a circular 5 pin connector that connects the control unit to the head amplifier via a 1m cable, on the left hand side of the control unit.
There is a separate head amplifier with a BNC connection that is connected directly to the BNC vacuum feedthrough. Note that this unit is intended to drive an open circuit, and must not be used to drive a load of less then 10Mohm.
24 Vdc (universal mains adapter supplied)
10 V to 400 V
+10 V to +400 V
~8 ns to 90%
~8 ns to 90%
DC to 10 kHz, BNC TTL trigger
Internal timer, 10 to 1000 ns, or follow rise & fall of trigger pulse
The IOE 10 Electron Beam is designed primarily for charge neutralisation during analysis of insulating materials. It provides high beam current density over a wide range of energy, from 10 microamps into 50 microns at 1000 eV to 1 microamp into 1 mm at 10 eV.
The low energy range is particularly suited to applications where electron stimulated desorption of ions (ESD) from the surface must be limited. ESD is generally seen to fall off as the electron impact energy reduces below 40eV. Use of low energy electrons also reduces localised heating of the sample surface.
Easy to Install
It is compact, fitting via an NW35CF flange, and can be made to suit any port to sample distance. A port aligner can also be fitted if required; this is especially useful for targetting the gun at low energy, when the beam is susceptible to any fields near the sample. The power supply is 1 U in height, for installation into a standard 19 inch electronics rack.
Easy to Use
Control of the electron gun is via a software interface. In addition to providing control of voltages, the software includes other convenient features, for instance the facility to store sets of operating conditions. This greatly simplifies switching between beam energies.
The IOE 10 can be pulsed, for TOF SIMS application. It is equipped with quadrupole deflection plates which can be used for static beam positioning or for rastering using an external scan system.
Imaging with the IOE 10
Whilst the IOE 10 is not intended to be used for imaging, it is a suitable means of demonstrating the gun’s spot size performance. The three images below show a 5 mm wide aperture strip with 1 mm apertures in the foreground. The 1 mm hole is still resolved by the 10 eV beam.
Images of an aperture strip using the IOE 10’s steering plates for rastering. (a) at 1 keV, (b) at 100 eV, and (c) at 10 eV.
High gain up to 6×107 @ 3 kV ensures maximum detection sensitivity
Multiplier has exceptional performance with high-gain stability and low noise
Not sensitive to light as is the case with photo-multiplier types
Simple procedure for replacement of channeltron
The detector assembly is designed with a small diameter profile enabling the detector to reach into space-restricted areas. It mounts via an NW35CF conflat flange with a standard length of 146 mm, adjustable over ±8 mm. All the detector’s internal components are vacuum compatible to < 1×10-9 torr. A bakeout temperature up to 160°C can be used with the preamplifer removed.
The preamplifier is housed in a compact assembly with a black anodised casing. It is attached directly to the SED to minimise cable connections and maximise signal to noise ratio. The pre-amplifier is easily removed by unscrewing a connector clamp ring. All electrical connections are made via a multipin connector on the rear of the pre-amplifer assembly.
Low noise, high bandwidth amplifiers are incorporated in the design to ensure high amplification across a broad range of frequencies up to TV rate. Control over signal gain and black level are provided via the computer controlled SED power supply.
SED Power Supply
The power supply is contained in a 2U high x 19” chassis. The supply is computer controlled and is designed to interface directly with the secondary electron/ion detector as part of an integrated imaging system. Digitally controlled analogue filter
Provides user programmable signal filtering over a wide range of frequencies. Communications
Full RS232 computer control with polled monitoring of unit status. Electron/Ion selection
The unit is able to support switching the detector between positive ion or negative electron detection mode, automatically setting the optimum voltage potentials for each mode. Slowscan / TV rate
Capable of handling slowscan generated signals up to and including TV rate imaging. Anti-aliasing filters, Black level clamping and a selectable auto gain control are employed to ensure a stable and optimised composite video signal. Current meter
Intended for measuring sample currents complete with auto ranging and an analogue output monitor for connection to an external meter if required.
Software Control Interface
The control software provides full control for all power supply outputs and includes programmable features.