Elemental mapping by the Auger microprobe
- The sample is a test structure for electromigration experiments (Blech test).
- It consists of Cu(Ag) alloy conductor lines embedded in Si oxide insulation with a Ta diffusion barrier.
- The gray images are secondary electron micrographs used for zooming to the analysis position (left column) and controlling sample drift (upper middle).
- The colored images are elemental distribution maps over the area shown in the upper right image (Magnification 20000x).
- The element name and the energy of the corresponding Auger peak are displayed above the image.
- The images shows the intensity of the peak above its background using a 256 level false color scale.
- The right column shows the result of line profile measurements along the marked line.
- For the elements of interest spectra are recorded at every point of the line.
- In the middle row the elemental concentrations are shown (128 points).
- The profile for Ta (256 points, lower row) shows the Ta diffusion barrier surrounding the Cu lines.
- The apparent barrier width of 220 nm is determined by the diameter of the electron beam, the true width is 20 nm.