Applications

 

During the interaction of electrons with matter also inelastic processes may occur. One is the generation of element specific x-ray fluorescence radiation which can be analyzed by means of energy dispersive x-ray spectroscopy (EDX). EDX spectra allow for the identification of elements as well as for a quantification (elemental ratio). The electrons may also suffer from an element specific energy loss due inner shell ionization while they pass through a specimen. Transmitted electrons with a different energy are separated by means of an electromagnetic prism and subsequently detected by a CCD camera. Additionally, by means of an adjustable slit, it is also possible to detect only such electrons, having energies within a very small range. It is therefore possible to map the elemental distribution of a certain element (energy filtered TEM or EFTEM).
The both methods, EDX & EELS, are somehow complementary. While EDX is typically used to detect heavier elements, EELS is more sensitive to light elements.

 

 

 

Technical Specifications

 

EDX

• Detection limit (material specific, Z > 5): 0.5% (heavy elements) to 5% (light elements)

• Lateral resolution: ~2nm

• Point spectra, line scan, spectrum imaging

 

EELS

• Detection limit (depending on element & matrix type): <2%

• All elements down to Z = 1 (Hydrogen)

• Lateral resolution: ~1nm

• Energy resolution: ~0.8eV

• Point spectra, line scan, spectrum imaging, energy filtered TEM

• Identification of chemical bonds from energy loss near edge structure (ELNES)

• Plasmon loss images

 

Research Areas

 

• Depth profiling of elements (e.g. in high-k dielectrics stacks)

• Elemental mapping of devices