EDS (Energy Dispersive X-ray Spectroscopy) and EELS (Electron Energy Loss Spectroscopy) are elemental analysis techniques integrated with electron microscopes such as TEM (Transmission Electron Microscope). Both techniques provide nanometer-level or atomic-level direct observations and semi-quantitative analysis into materials elemental distribution and concentration, enabling accurate measurement of small complex structures such as FINFET or 3D NAND.

However, the analysis of EDS and EELS require different tool configurations, electron beam settings and analysis approaches. It is often not clear which technique is more appropriate for a certain analysis.