Evaluation of secondary electron intensities for dopant profiling in ion implanted semiconductors: a correlative study combining SE, SIMS and ECV methods

This study evaluates the secondary electron (SE) dopant contrast in scanning electron microscopy (SEM) and helium ion microscopy (HIM) on boron implanted silicon sample. Complementary techniques like secondary ion mass spectrometry and electrochemical capacitance voltage (ECV) measurements are used to understand the dopant profile and active dopant distribution before and after a thermal firing, a step carried out to remove implantation damage and to electrically activate the implanted boron. Thermal firing resulted in an activation efficiency of 33%. HIM showed higher contrast than SEM having more defined peak with a lower background contribution. Variations in dopant concentration near the peak maximum were observed in ECV measurements, which was not observed in the intensity profiles from both SEM and HIM. This study demonstrates the effectiveness of SE dopant profiling as a quick tool to map the electrically active dopant concentrations even in far-from-equilibrium materials such as ion implanted samples.