The Full Form of FESEM is‍ Field Emission Scanning Electron Microscope.

Field emission scanning electron microscopy (FESEM) provides topographical and elemental information at magnifications of 10x to 300,000x, with virtually unlimited depth of field.  Compared with convention scanning electron microscopy (SEM), field emission SEM (FESEM) produces clearer, less electrostatically distorted images with spatial resolution down to 1 1/2 nanometers – three to six times better.

Other advantages of FESEM include:

• The ability to examine smaller-area contamination spots at electron accelerating voltages compatible with energy dispersive spectroscopy (EDS).
• Reduced penetration of low-kinetic-energy electrons probes closer to the immediate material surface.
• High-quality, low-voltage images with negligible electrical charging of samples (accelerating voltages ranging from 0.5 to 30 kilovolts).
• Essentially no need for placing conducting coatings on insulating materials.

For ultra-high-magnification imaging, we use in-lens FESEM.

Applications: Applications of FESEM include:

• Semiconductor device cross section analyses for gate widths, gate oxides, film thicknesses, and construction details
• Advanced coating thickness and structure uniformity determination
• Small contamination feature geometry and elemental composition measurement