Archive for category: Products

High-resolution ion column

Pioneer features a mass-filtered ion column, with a 20nm spot size, and operates at up to 30kV. This enables incredibly accurate placement of ions within the substrate, subject to scatter.

Two versions of the ion source are available: a liquid metal source and a duoplasmatron, giving you access to a large number of dopant ions.



Deterministic ion implantation

Detection of implant events is critical to deterministic ion implantation. Up to four high-gain, low-noise detectors enable high-efficiency detection of secondary particles (both ions and electrons), offering detection efficiency of better than 85%.



Nanometer precision stage

The stage is a piezo-driven precision stage, with optical encoders with 1nm precision, and is capable of handling up to a 6-inch wafer. There is also a load lock for fast sample insertion and optical cameras for precision alignment.



Proprietary software

Pioneer is completely software driven, and includes implantation UI, SED imaging, vacuum control and monitoring, stage control, and sample transfer. The software is designed to enable fully automated, overnight operation (for high-noise environments). It also offers alignment to pre-defined sample marks, with better than 20nm accuracy.



High-vacuum system

A 6-inch wafer carrying load-lock enables fast sample insertion while maintaining a consistent high-vacuum in the chamber (< 1x10-8 mbar), while a gate valve on the ion column protects the chamber vacuum and allows sources to be swapped quickly.



High-resolution electron column

A 20nm electron beam is available for high resolution imaging.



Applications of Pioneer

In addition to precision ion implantation at the nanoscale, pioneer can also achieve deterministic single-ion implantation. This means that the instrument provides a versatile platform for doping and implantation with both multiple- and single-ion species. The versatility of pioneer is expected to create an invaluable resource in application areas such as:

  • Quantum Technologies
  • Quantum Device Fabrication
  • Nano-material Doping
  • Photonic systems
  • Memory Devices


Installations

SIMPLE

Ionoptika Ltd installed the first two instrument of its kind at the Surrey Ion Beam Centre in 2018, as part of the Single Ion Multi-species Positioning at Low Energy (SIMPLE) project. Read more about this exciting project here.

P-NAME

Ionoptika Ltd is delighted that our Pioneer system features at the heart of the new PLATFORM FOR NANOSCALE ADVANCED MATERIALS ENGINEERING (P-NAME) at the Henry Royce Institute, Manchester.

High-resolution, low-current ion column for precise placement of ions
Liquid metal or duoplasmatron ion source
Wide range of available dopant ions
Nano-precision stage with up to 6-inch wafer handling capability
Deterministic ion implantation detection system
High-resolution electron column available for non-destructive imaging

The Need for Low Energy 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.

Current vs spot size for the FLIG

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.

Depth profiles of SiGe lattice

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.

Beam Energy Range:200 eV to 5 keV
Max. Current (5 kV):> 500 nA
Min. Spot Size (5 kV, 500 nA):< 15 μm
Max. Current (1 kV):> 350 nA
Min. Spot Size (1 kV, 100 nA):< 25 μm
Max. Current (250 eV):> 250 nA
Min. Spot Size (250 eV, 100 nA):< 50 μm

Installation Requirements

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.



Electronics

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.

SED imaging with 30 keV helium beam, 50pA, achieving 100 nm spatial resolution

Figure 1. SED imaging with 30 keV helium beam, 50pA, achieving 100 nm spatial resolution. Image courtesy of National Institute for Materials Science, Japan.

Beam Energy Range:5 to 30 keV
Source Lifetime:> 400 hrs
Beam Stability:< ±2% / hour after 2 hour warm up
Max. Beam Current (Ar+ @ 30 KV):> 500 nA
Min. Spot Size (Ar+ @ 30 KV):< 300 nm
Mass filter:Yes
Column Isolation Valve:Yes

Overview

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.



Ion Optics

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.



Electronics

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

Schematic of IOG25GA Ion Optics



Performance

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

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

Field of view of IOG 25GA is > 2.5 x 2.5 mm



Installation

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

Key dimensions of the IOG 25GA



Optional Equipment

The following items are also available from Ionoptika, for use with the IOG 25GA:

Beam Energy:10 to 25 keV
Current Range:20 pA to 20 nA. Option for 50 nA.
Resolving Power:<: 50 nm (subject to suitable vibration isolation)
Source Lifetime:>: 500 μA hrs
Computer InterfaceRS232

Performance

The most useful species that can be selected by the mass filter are as follows:


Species% of Beam Current
Au+58.9
Au++16.2
Au2+6.4
Au3+4.3
Au3++1.4

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.

iog25au - Absolute ion yields from a thin film of PS2000

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.

Secondary electron images of a 12.5 micron repeat copper grid.



Ion Optics

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
  • aperture selection
  • deflection plates for blanking the beam
  • pulse bunching units
  • raster plates

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:

  • Source Voltage
  • Extractor Voltage
  • Lens 1 Voltage
  • Lens 2 Voltage
  • Stigmation (amplitude and angle)
  • Alignment
  • Heater Current


Installation

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


Optional Equipment

The following items are also available from Ionoptika, for use with the IOG 25AU:

The gun can be connected to alternative scanning or pulsing electronics if desired.

Beam Energy:5 to 25 keV
Max Current:10 nA
Minimum spot size:< 50 nm
Computer Interface:RS232
Power requirements:110 / 220 Vac (50 / 60 Hz)

Overview

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.

3D CAD Model of the GCIB 40 Gas Cluster Ion Beam



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.

Enhanced ToF-SIMS signal intensity at higher beam energies

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.

Data obtained with GCIB 40 on J105 SIMS

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[39]); 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 System

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.

3D CAD Model of the GCIB 40 with labels

Beam Energy:5 to 40 keV
Range of selectable cluster ions:(CO2)1 to > (CO2)1
(CO2)1 maximum current:> 300 pA with a spot size of < 50 μm
(CO2)1 minimum spot size:< 3 μm
(CO2)2000> 200 pA with a spot size < 50 μm
(CO2)2000< 4 μm
Maximum scan field @ 40 kV:0.9 mm x 0.9 mm

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

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 Imaging SIMS with GCIB

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.

Sub micon resolving power of the GCIB SM

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 System

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

Schematic layout of the GCIB-SM

Beam Energy:20 kV to 70 kV
Selectable Cluster Sizes:CO2(1) to CO2(10k)
Minimum Spot Size:< 1 μm
CO2(10k) Maximum Current> 1 nA

Description

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.



Connections

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.

Power input:24 Vdc (universal mains adapter supplied)
Housing:Discrete box
Voltage Output:10 V to 400 V
Set Voltage:+10 V to +400 V
Rise Time:~8 ns to 90%
Fall Time:~8 ns to 90%
Rep Rate:DC to 10 kHz, BNC TTL trigger
Pulse Width:Internal timer, 10 to 1000 ns, or follow rise & fall of trigger pulse
Output Connection:BNC