Site-selective dopant profiling of p-n junction specimens in the dual-beam FIB/SEM system

Abstract

Results from site-specific dopant profiling in a dual-beam FIB/SEM system are reported. Si specimens containing p-n junctions were milled using Ga+ ion beam energies ranging from 30 keV to 2 keV, and analysed in situin the vacuum chamber. We compare the dopant contrast observed when milling a cleaved surface to that obtained from a side-wall of a trench cut using 30 kV Ga+ ions, and using successively lower ion beam energies. The latter technique is suitable for site-specific dopant profiling. We find that lower energy ion beam milling significantly improves contrast, but only achieves 50 % of that observed on a freshly-cleaved surface. Furthermore, the contrast on a side-wall previously milled using high energy Ga+ ions is less than that of a cleaved surface subjected to the same ion beam energy.