About the technique
A FIB-SEM combines the high resolution imaging capabilities of an electron microscope with the precision milling capability of a focussed ion beam thus allowing the user to manipulate tiny regions of their sample with a high degree of accuracy whilst monitoring the process.
How it works
The ion beam is produced from the field emission of gallium (Ga+) ions from a liquid metal ion source. The ions are then accelerated (typically to 30 keV) and focussed by electromagnetic lenses. Apertures are then used to control the beam current and scanning lenses make the beam raster the sample surface in a similar way to the electron beam. When the Ga+ ions impact the sample surface it sputters a small amount of material, which leaves the surface as either secondary ions or neutral atoms. The primary beam also produces secondary electrons which can then be used for imaging.
Site specific sample preparation
One of the main uses of a FIB-SEM is to prepare samples from particular regions of a bulk sample for further analysis by atom probe, transmission electron microscopy or transmission Kikuchi diffraction. This is achieved by using the ion beam to mill away the surrounding material and using a nanomanipulator to transfer the region of interest to a relevant sample holder. A gas injection system is used to deposit material, such as platinum, to create a bond between the sample and either the nanomanipulator or the sample holder. Finally further milling is used to either make the sample thin enough for transmission analyses or sharp enough for atom probe analysis.
Microanalysis
The Tescan LYRA is fitted with a wide range of detectors to allow a range of microanalyses to be performed. The electron beam enables typical surface analyses such as imaging, EDS and EBSD. The ion beam enables the sub-surface to be analysed using the ‘slice and view’ technique. This allows the microstructure and chemical composition to be studied in three dimensions (3D imaging, 3D EDS, 3D EBSD).
One of the features of the LYRA microscope is that it is fitted with an orthogonal TOF-SIMS. Using the FIB as the primary ion source, the secondary ions sputtered from the sample are collected and identified with a medium mass resolution. The precision optics of the FIB produce TOF-SIMS analyses with impressive spatial resolution (better than 50 nm lateral and 15 nm depth can be achieved). This allows for 3D chemical mapping with the different isotopes being distinguishable.
How it works
The ion beam is produced from the field emission of gallium (Ga+) ions from a liquid metal ion source. The ions are then accelerated (typically to 30 keV) and focussed by electromagnetic lenses. Apertures are then used to control the beam current and scanning lenses make the beam raster the sample surface in a similar way to the electron beam. When the Ga+ ions impact the sample surface it sputters a small amount of material, which leaves the surface as either secondary ions or neutral atoms. The primary beam also produces secondary electrons which can then be used for imaging.
Site specific sample preparation
One of the main uses of a FIB-SEM is to prepare samples from particular regions of a bulk sample for further analysis by atom probe, transmission electron microscopy or transmission Kikuchi diffraction. This is achieved by using the ion beam to mill away the surrounding material and using a nanomanipulator to transfer the region of interest to a relevant sample holder. A gas injection system is used to deposit material, such as platinum, to create a bond between the sample and either the nanomanipulator or the sample holder. Finally further milling is used to either make the sample thin enough for transmission analyses or sharp enough for atom probe analysis.
Microanalysis
The Tescan LYRA is fitted with a wide range of detectors to allow a range of microanalyses to be performed. The electron beam enables typical surface analyses such as imaging, EDS and EBSD. The ion beam enables the sub-surface to be analysed using the ‘slice and view’ technique. This allows the microstructure and chemical composition to be studied in three dimensions (3D imaging, 3D EDS, 3D EBSD).
One of the features of the LYRA microscope is that it is fitted with an orthogonal TOF-SIMS. Using the FIB as the primary ion source, the secondary ions sputtered from the sample are collected and identified with a medium mass resolution. The precision optics of the FIB produce TOF-SIMS analyses with impressive spatial resolution (better than 50 nm lateral and 15 nm depth can be achieved). This allows for 3D chemical mapping with the different isotopes being distinguishable.