IOG 25AU

Gold Liquid Metal Ion Beam

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.

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Key Features

Gold-germanium liquid metal ion source.
Small spot size of down to 100 nm.
Wien filter for selection of different species
Mass filtered beam available in both DC and pulsed mode

Details Specifications

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.

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.

Principle application	Analysis
Energy range	5 keV to 25 keV
Min. spot size	100 nm
Max. beam current	10 nA
Max. scan size	1 mm x 1 mm
Flange to nose length	170 mm
Recommended working distance	25 mm
Rack space required for electronics	6U x 19″ rack mountable unit
Electrical requirements	110-240 VAC 13A 50/60 Hz)
Software requirements	PC running Windows 10 or later
Flange type	NW 63 CF