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High performance research TOF-SIMS system


A USA government laboratory required a complex, high performance TOFSIMS designed to meet their unique materials analysis requirements. Kore designed, built and installed the required instrument for a price significantly lower than if the laboratory had bought a modified standard TOFSIMS from one of the propriety manufacturers.

The system uses our proven R500 TOFSIMS time-of-flight mass spectrometer and a two lens 25KV liquid metal ion gun, with bunching plates and a Wien filter. The system provides high spatial resolution in positive and negative SIMS modes, at all ranges of magnifications on the SIMS extraction lens. Bunching creates nanosecond length pulses and allows high-mass resolution to be realised without reducing primary currents. However, the spatial resolution of the probe is compromised in the process(200nm), and this mode is not suitable for high spatial resolution imaging. A high mass resolution mode with the full lateral resolution of the LMIG in pulsed mode is also provided using delayed extraction tuning of the stage extraction pulse. The Wien filter is required when using alloy sources whose ion beams contain multiple species, to provide primary mass filtering.

Depth profiling is provided in positive and negative SIMS modes with a two- gun, interleaved mode. The LMIG pulses for durations of 10-100ns each cycle and forms the analytical beam. A separate sputter gun, set at suitably low primary beam energy, is pulsed for durations of 10-50µs each cycle.

High spatial resolution in positive and negative SIMS modes with low energy electron charge compensation of insulators, at lower magnifications on the SIMS extraction lens is also provided.

Samples enter via a fast entry lock and can then be processed in an extensive preparation chamber with multiple sample heating/cooling and deposition facilities. Samples can be heated to 600°C using either fast or slow ramping to a set temperature or to a set of temperature plateaus. Apart from sample cooling in the preparation chamber all of the analysis modes can be performed at sample temperatures down to 85K, using a cryo-cooled stage in the main analysis chamber.

There is provision for expansion in this TOFSIMS to include XPS and laser beam post ionisation of neutrals as well as further sample conditioning. Complete data processing software was also provided to make this a complete system designed built and tested by Kore to meet the client's requirements.


Thursday, March 22, 2007, 15:55

© Kore Technology Limited 2007