Dual Beam – Focused Ion Beam (Dual Beam – FIB)

Dual Beam – Focused Ion Beam (Dual Beam – FIB)

A focused ion beam (FIB) system uses ions (usually Gallium), operated at sufficiently high beam current, focused upon specific areas of a sample, for sputtering or milling, at nanometre scale precision. When FIB is combined with Scanning Electron Microscopy (SEM) it forms a dual beam system that can simultaneously accomplish nano-scale milling and high-resolution imaging using emitted electrons.

This technique combines the precise nano-milling capabilities of FIB with the imaging capabilities of SEM. In a typical Dual Beam – FIB system the electron and ion beams intersect at a 52° angle at proximity to the sample surface. This enables the detection of electrons by SEM as soon as they are emitted from an FIB milling location, providing simultaneous high resolution SEM imaging. The Dual Beam-FIB technique has many applications in emerging semiconductor and nano-technology sectors, ranging from preparation of ultra-thin or ultra-sharp TEM/APT samples in 50nm-100 nm range, nano-component fabrication by FIB milling, to building nanostructures by chemical vapor deposition.

 Common Uses of Dual Beam – FIB

• Preparation of ultrathin (<100 nm thick) sample slice for Transmission Electron Microscopy (TEM)
• Preparation of ultrasharp tipped (<50 nm thick) needle for Atom Probe Tomography (APT)
• High resolution cross-section images of small, hard-to-access sample features
• Lift-out in-situ samples for study, while milling
• By combining sequential SEM images during FIB milling of a given area a 3D reconstructed image of that volume element can be obtained (3D-tomography)
• Materials and devices can be characterized for electrical and mechanical properties in situ, using tungsten probe micromanipulator with FIB and simultaneous SEM observation
• Any nanoscale shape can be milled into substrates, to form custom built nanostructures.

 Advantages of Dual Beam – FIB

•  Ability to cross-section small samples for TEM
• High-resolution (~2 nm) imaging
• Good image contrast
• Versatile: can be adapted to perform milling, imaging, cutting and welding of nano-materials to new substrates.

 Limitations of Dual Beam – FIB

• Samples must be vacuum compatible
• Imaging may spoil subsequent analyses
• Gallium ions may cause sample damage such as Gallium implantation, and atomic dislocations
• Ion beam damage may limit image resolution
• Cross-section area is small

 Industrial Applications of Dual Beam – FIB

• Nanotechnology
• Semiconductors