An Advanced SEM-FIB Dual Beam Microscope for Three-Dimensional Mesoscale Fabrication, Imaging and Analysis

Lead Research Organisation: University of Cambridge
Department Name: Materials Science & Metallurgy


The growth and fabrication of modern structures and devices has now developed in order to exploit the full three-dimensional behaviour of the materials used. Whether its in structural materials, such as ultra-fine ceramic-metal composites, or in functional materials, where transistor structures composed of a 3D 'latticework' of key components, there is a pressing need to understand the structure, composition and physico-chemical properties of modern materials in three dimensions. Over the past 5 years we have developed transmission electron tomographic techniques to investigate, with nanometre resolution, the internal architecture of many materials systems, including heterogeneous catalysts, nanotubes and quantum dots. However, it is important to link the structure-properties relationships over many length scales, from nanometres (10-9m) to microns (10-6m) through to millimetres (10-3m). Although, x-ray tomography and related techniques are used with great effect at length scales ~ few microns, this proposal addresses the development of techniques to give the ability to analyse, in three dimensions, the structure and composition of a range of materials at a meso-scale, from 10's microns to 10 nm, bridging the gap between transmission electron tomography and x-ray tomography.Such 3D analysis can now be undertaken using a combined scanning electron microscope (SEM) / focussed ion beam (FIB) microscope. This instrument, known as a 'Dual Beam microscope', uses the milling action of a gallium ion beam to reveal internal surfaces and an electron beam to record successive image slices (to give 3D morphology). Either secondary electrons (for maximum surface detail) or back-scattered electrons (which has atomic number contrast) can be used to form images.The instrument will have a field emission gun (FEG) electron source for optimum brightness and image resolution, and advanced analytical tools including an electron backscattered diffraction (EBSD) detector for 3D crystallographic studies, and an energy-dispersive X-ray (EDX) detector system to map the composition of the specimen in 3D. It will have an internal micromanipulator for handling micron-sized specimens and an in-situ straining stage will be incorporated to measure the mechanical response of micron-sized components. As well as yielding new areas of research combining electron and ion sources, the individual components of the Dual Beam will have a performance better than any of the single-beam SEMs and FIB currently available to us. In particular, the EBSD system will be ~100x faster than our present system and milling times with the FIB reduced by up to a factor of 5.In addition to the 3D imaging and analysis, we propose to use a dual beam workstation to fabricate novel electronic device structures and develop novel sample geometries for a wide range of state-of-the-art transmission electron microscopic techniques. In particular, for TEM specimens the dual beam requested in this proposal allows low energy ion thinning of membranes to remove implantation damage. Subsequent micromanipulation of the plucked free-standing membrane onto a specially prepared grid will then allow full 360 degree tilt and rotation when in the TEM, vital for advanced electron tomographic analysis.


10 25 50

publication icon
Beyer Y (2012) Low voltage STEM imaging of multi-walled carbon nanotubes. in Micron (Oxford, England : 1993)

publication icon
Burdet P (2014) Enhanced quantification for 3D energy dispersive spectrometry: going beyond the limitation of large volume of X-ray emission. in Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada

Description The FEI Helios 600 Nanolab is a dual-beam microscope for high spatial resolution imaging, fabrication and analysis. The instrument is used as a multi-user, multi-project platform to enable a broad range of materials science. By the end of the grant period, the instrument had been used by 34 researchers, working on 46 different materials/projects, across a wide spectrum of materials science; industrial links include Rolls-Royce, Michelin and Henkel. Materials studied include cortical bone, semiconductors, alloys, superconductors, functional and structural oxides. Techniques developed include low voltage SE and STEM, 3D imaging, sample fabrication, 3D EDS and 3D EBSD, forward scattered imaging (ECCI), mesoscale fabrication.

Examples of projects below:
A. Techniques. The development of low-voltage STEM, using a multi-segment transmission detector, led to a successful analysis of multi-wall carbon nanotubes. Remarkably high contrast BF, ADF and HAADF images were understood through scattering theory and Monte-Carlo simulations. 3D back-scatter diffraction (3D EBSD) and x-ray microanalysis (3D EDS) was developed with FEI and Oxford Instruments. For 3D EBSD, orientation maps, determined pixel by pixel by EBSD patterns analysis, acquired successively using FIB routines, yield a 3D volume (~1/2 million voxels) of orientation data. Using 3D EBSD, for the first time we could achieve a 3D orientation analysis of a single plastically-deformed micropillar, revealing the intricate mix of high deformation regions and crystal rotations. Angular resolution achieved of ca. 0.5 deg, and spatial resolution of (50nm)3, makes this a unique 3D tool with enormous potential for materials characterization. 3D EDS was implemented using low energy primary beams to retain high spatial resolution and ongoing work is addressing how best to accurately deconvolve overlapping spectral information. An adapted slice-and-view method, using the ion beam both for milling and imaging, proved very successful in understanding the morphology in inter-dendritic regions of CMSX superalloy. In this 'top down' approach surfaces are revealed perpendicular to the ion beam. This work expanded into a separate DTP project investigating the 3D microstructure of RR1000 and 718 superalloys. Progress towards true 3D nano-metrology was made investigating optimum imaging and milling parameters and minimizing sources of measurement error.
B. Fabrication. A key aspect of the instrument is the fabrication of site-specific TEM samples. Large lamellae were fabricated from high Tc superconductors for imaging flux vortices (holography / Lorentz TEM): we observed the structure and dynamics of vortices in MgB2, a world first (paper in preparation). Many needle-shaped specimens were fabricated for electron tomography and atom probe tomography e.g. GaN-based quantum well structures. CPP device fabrication was achieved, micropillar fabrication for nano-indentation was successful and mesoscale structures were fabricated from Ag films as part of a program of plasmonics research. The Helios continues to work well, many years after the grant end, and is used routinely, with a large number of ongoing projects and users. It is a key instrument for the Department.
Exploitation Route The installation of the dual beam has led to a variety of new applications and the development of new techniques, which are ongoing. The Helios is now a part of the Wolfson Electron Microscopy Suite in the department, open to all in the university and so is very much a multi-user multi-project facility. It has been central in the development of a number of projects Department-wide ranging from new low kV imaging, 3D composiotnal and morphological imaging, fabrication of nanostrcuctures and micro-pillars. The dual beam instrument continues to be used all day, every day enabling a range of materials science. Many of the projects run on the instrument are in collaboration with industrial partners, including for example Rolls-Royce, with whom we have developed 3D imaging methods tailored towards investigating the microstructure of Ni-base superalloys. In addition, as a further example, by being able to fabricate needle samples, this has given rise to a new avenue of research in STEM - EDX tomography to map 3D compositions at the nanoscale. Without the dual beam being able to fabricate the needle sepcimens that technique development would have been impossible.
Sectors Aerospace, Defence and Marine,Chemicals,Electronics,Energy,Manufacturing, including Industrial Biotechology,Transport

Description The installation of a dual beam microscope has enabled a great deal of nanoscale science that would otherwise have been difficult or impossible. The instrument was used (and continues to be used) in many different ways. Firstly, the instrument is used as a high resolution analytical SEM and STEM. We have recently added a new EDS detector that allows much faster and more accurate chemical mapping. We continue to use the EBSD camera for orientation mapping, used especially by those studying polycrytsalline alloys and steels. We have developed low kV STEM which is of particular benefit for low Z (e.g. carbonaceous) materials where knock-on damage in a TEM may be problematic. We use it as a tomographic instrument that allows 3D views of the morphology and composition. We have developed a new 3D ion beam imaging technique that has been of great use styudying Ni-base superalloys (collaboration with Rolls Royce) and recently implemented a new 3D compositional mapping routine that exploits both low energy and high energy X-ray lines. In terms of fabrication, the Helios is used routinely for fabricating TEM lamellae and needles. The latter have been espcially important in the development of STEM-based electron tomography where we wish to look at featrures at the nanoscale in 3D but also from large volumes - the needle geometry is ideal for this form of tomography. Thick sections from high Tc superconductors have also been fabricated that have allowed detailed examination of the structure and dynamics of flux vortices.
First Year Of Impact 2009
Sector Electronics,Energy,Manufacturing, including Industrial Biotechology,Transport
Impact Types Societal,Economic

Description EPSRC / RR DTP Studentship
Amount £153,656 (GBP)
Funding ID EPSRC/RR DTP studentship (from EP/H022309/1) 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 10/2010 
End 09/2014
Description FEI UK Ltd
Amount £66,900 (GBP)
Organisation FEI company 
Sector Private
Country United States
Start 06/2010 
End 06/2014