Focused Ion Beam Scanning Electron Microscopy (FIB-SEM)

Frequently Asked Questions

Identifying the right test can be complex, but it doesn’t have to be complicated.
Here are some questions we are frequently asked. 

• What is FIB-SEM used for?

  FIB-SEM (Focused Ion Beam – Scanning Electron Microscopy) is a powerful dual-beam instrument for microscale and nanoscale imaging, material modification, and analytical characterization. It combines the capabilities of a scanning electron microscope (SEM) for high-resolution imaging with a focused ion beam (FIB) for site-specific milling, deposition, and sample preparation.

• How do you interpret FIB-SEM images?

  Interpretation of SEM images of FIB cross sections relies on understanding how different contrast mechanisms relate to sample features, beam settings, and detector types. For topographic contrast using secondary electrons, bright areas are the sample’s regions facing the detector, whereas dark areas are recessed or shadowed. This allows one to identify cracks, voids, fibers, surface roughness, and 3D surface shapes. For compositional contrast using backscattered electrons, bright areas are higher atomic number elements, and darker areas are lower atomic number elements (gold vs carbon). This type of contrast allows one to identify inclusions, multi-phase materials, contamination, and coating layers. Be sure to pay attention to the scale bar when comparing the relative sizes of features in the SEM image of a FIB cross-section. When measuring the length of a vertical feature in a FIB cross-section (i.e., thin film thickness), it is essential to know the stage tilt at which the image was collected (typically 52 degrees). When using the horizontal scale bar when measuring the thin film thickness, one must multiply that value by the cosine of the complementary angle (i.e., cosine(38 degrees)) to calculate the film thickness.

• What level of resolution can FIB-SEM achieve?

  Under high-resolution conditions with a Ga⁺ focused ion beam (FIB), the best lateral resolution is ~5–10 nm. For imaging, a field emission scanning electron microscope (SEM) can reach sub-nanometer spatial resolution in ultra-high resolution mode.

• Which industries commonly use FIB-SEM for failure analysis or microfabrication?

  FIB-SEM is widely used in semiconductors, microelectronics, batteries, and the energy industry for precise cross-sectioning, defect analysis, and microfabrication.

• What elemental sensitivity can be achieved with EDS in FIB-SEM?

  Energy Dispersive X-ray Spectroscopy (EDS) in FIB-SEM is semi-quantitative and accurate within 0.1 weight percent. However, EDS cannot detect H, He, or Li with most detectors, and sensitivity to light elements (B, C, N, O) is reduced due to low X-ray yields and overlaps.

• How is beam-induced damage minimized during FIB-SEM analysis?

  Beam damage can be minimized by lowering beam energy and current to reduce the dose. This approach applies to both the electron beam and the focused ion beam, making it essential for analyzing sensitive samples.

• What are the advantages of integrating EBSD or EDS with FIB-SEM?

  Integrating EDS provides localized chemical composition analysis of cross-sectioned regions, enabling material identification of subsurface features. EBSD (Electron Backscatter Diffraction), under specialized conditions, can be combined with FIB-SEM for localized crystallographic mapping, revealing grain boundaries, phase orientation, and texture.

• When should FIB-SEM be used instead of traditional SEM or TEM?

  FIB-SEM is necessary when subsurface features must be accessed. Traditional SEM is surface-limited, while FIB enables precise cross-sections. FIB-SEM is also used to prepare TEM lamellae. TEM areas are typically 5–10 µm wide and only a few microns deep, while FIB-SEM cross-sections can reach up to 100 µm wide and tens of microns deep.

• What are the sample preparation requirements for FIB-SEM analysis?

  • Metals: Minimal preparation needed due to high conductivity.
  • Ceramics/Polymers: Often require thin conductive coatings and grounding layers to avoid charging.
  • Semiconductors: Can often be analyzed at low voltages without coating, but coatings are usually required when devices or passivation layers are present.

  Good sample conductivity is critical. Non-conductive or unstable samples may drift or accumulate charge, reducing cross-sectioning accuracy.

• What are the limitations of FIB-SEM for material analysis?

  • Vacuum requirement: Samples must be vacuum-stable; liquids or volatile materials are not compatible.
  • Resolution: Lower than TEM; worsens with beam broadening at high voltages or in low-Z materials.
  • EDS sensitivity: Cannot measure H, He, or Li; reduced accuracy for light elements.
  • Sample sensitivity: Biological and organic materials may degrade under beam exposure.