High Resolution Mapping of a Semiconductor Structure Using STEM-EDS in SEM (T-SEM)

Element distribution mapping of semiconductor nanostructures with X-ray based methods is not always straight forward. The need of nanoscale spatial resolution and X-ray peak overlaps are common challenges when investigating semiconductor materials. SEM in transmission mode (T-SEM) can sometimes substitute the expensive TEM. The present example shows a high-resolution EDS map of a semiconductor structure acquired in SEM using an annular XFlash® FlatQUAD EDS detector with 4 SDD quadrants arranged with radial symmetry between the specimen and the SEM pole piece. The map was acquired at 20 kV with 220 pA beam current. The high sensitivity of the XFlash® FlatQUAD detector allows to achieve better than 10 nm spatial resolution (see Fig. 2) in SEM. Despite strongly overlapping X-ray peaks, silicon (Si) and tungsten (W) can be well distinguished in the map thanks to peak deconvolution models implemented in the Bruker' ESPRIT software (see Fig. 1).  

Fig. 1: Elemental distribution map of a RAM microchip and extracted area spectra proving the successful deconvolution of Si and W
Fig. 2: Line scan extracted from the HyperMap in Fig. 1: It reveals the variation in element distributions along the profile, with a lateral resolution of 10 nm.