Direct determination of p/n junction depth by the emission of matrix complex ions

Abstract

The charging effect of n- and p-type layers of silicon under oxygen ion bombardment in an SIMS instrument was used to explore the possibility of determining the p/n junction depth. Complex ions like Si 2O 4 or Si 2O 5 (negatively charged) were recorded because of their narrow energy distributions and, hence, their sensitivity to changes of the surface potential. In the case of a p/n junction, a characteristic shift of the surface potential, as seen in the Si 2O 5 intensity profile, coincides with the depth of the metallurgical junction. In the case of an n/p junction, though, the marked intensity change is short by 250 nm of the metallurgical junction depth and appears to coincide with the onset of the depletion zone.