Acquisition of a Helios 5 UC Focused Ion Beam

The Niels Bohr Institute is part of the Faculty of SCIENCE at the University of Copenhagen. The Niels Bohr Institute has a 100 year long tradition of excellence within science, in particular within the area of quantum physics. The institute was inaugurated on March 3, 1921, by Professor Niels Bohr. We are approx. 430 researchers, 70 administrative and technical staff, 100 PhD students and 400 students. The European Physical Society has declared the Niels Bohr Institute a Historic Site of great international importance for the development of physics and research.

A focused ion beam (FIB) is essential for our characterization efforts here at NQCP.

The FIB will be one among a handful of highly specialized characterization tools that will be used daily. Each will give essential feedback for troubleshooting and improving materials grown at the Quantum Foundry. Modern FIB models are highly automized, enabling fast and consistent lamella production, allowing microscopy with atomic resolution inside of materials. This specific model has unrivalled automatic lamella production, both in terms of reliability and lamella geometry.

The following is crucial for our choice of focused ion beam (FIB):

Software enabling automatic lamella production.

This tool comes with world-leading software for production of lamellas, AutoTEM 5. It has outstanding yield on regular lamella production and can do inverted and horizontal lamellas as well. This paper elaborates the yield:

Tsurusawa, H., et al, Sci Rep 11, 21599 (2021)

Of course, software alone is not enough to achieve good performance. The ThermoFisher Dual BeamTM technology is also leading on many parameters, some of which are elaborated below:

Precise nanomanipulator is required.

This tool has a fully integrated nanomanipulator, Easylift, with no more than 15 nm of vibrations and less than 50 nm/min of drift, omnidirectional repeatability <150nm, an inert/retract accuracy less than or equal to 2 μm. This is part of insuring the high yield on automatic lamella production.

Versatile and stable FIB is required.

This FIB has a range of 500 eV to 30 keV, 0.1 pA – 100 nA beam current that is time-of-flight corrected giving it excellent low energy performance, enabling production of very thin lamellas.

High current density saves time.

This tool must have at least 40 A/cm2 current density to ensure fast milling with the FIB.

FIB column spot size must be minimal.

This product provides a >7µm spot size at

100 nA. This is, to our knowledge, the lowest on the marked and allows for precise FIB milling.

Low electron beam current is needed for sensitive samples.

For beam sensitive samples, <5pA beam current is required for controlling beam damage. The smaller beam current has smaller spot size to obtain better spatial resolution. Helios has the lowest beam current of 0.8pA in the market.

Ease of lamella thinning is important.

The lowest energy ion beam (500 eV) must provide a clear view of a TEM lamella at the final polishing stage of an in-situ lift-out sample preparation. The boundaries of a lamella 10um long by 100nm thick must be resolved in order to position the beam on the lamella to remove residual amorphization and gallium implantation damage of less than 1nm.

Repeatable stage movement is key.

The tool must have a XY repeatability of at least 1 µm and a tilt accuracy of 0.1 degrees or smaller. This is required for precise and reproducible lamella production.

State of the art STEM detector is crucial.

This tool comes with a retractable, single crystal STEM detector with annular BF and DF regions and a segmented annular HAADF region, 11 segments in total. Thermo Scientific is the only supplier on the market to be able to offer and demonstrate a retractable STEM detector unit with bright field (BF), segmented dark field (DF) for fine chemical contrast tuning, and a 6-segment high angle (annular) dark field (HAADF). The 4 concentric DF segments uniquely provide additional information not available by other STEM detectors on SEM or FIB-SEM instruments.