Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) has become less useful for semiconductor samples as feature dimensions decrease. It has become increasingly difficult to get sufficient signal from small features because of the large interaction volume of the primary beam. As the interaction volume is dependent on the accelerating energy of the primary electron beam, decreasing the accelerating voltage will decrease the interaction volume. This increases the percentage of signal from the feature of interest, but also lowers the number of peaks available for interpretation, reducing the sensitivity of the analysis. Several elements commonly used in the fabrication of semiconductors have overlapping peaks at lower energies, and the ability to distinguish between them is lost at low accelerating energies. It is possible to modify samples using Focused Ion Beam (FIB) to improve EDS resolution without decreasing the accelerating voltage.

The samples were prepared in an FIE 800 FIB and imaged in an Hitachi S-4700 SEM.