Progress towards site-specific dopant profiling in the scanning electron microscope

Abstract

2-dimensional dopant mapping in the scanning electron microscope is based on the variation of contrast as a function of differences in the number of active dopant atoms. It was put forward as a potential technique for dopant mapping on the nano-scale in response to the challenge of ever-shrinking device dimensions. Its impact, so far, has been limited as the majority of the work has concentrated on sample preparation by cleaving, thus not achieving the site-specificity which is required for nano-scale electronic devices. It was previously shown that cross-sections prepared using a 30 kV gallium focused ion beam (FIB), results in such strongly reduced dopant contrast (DC) that quantification is impossible. We demonstrate that by the use of a final in-situ argon broad ion beam (BIB) milling operation, contrast from a FIB prepared cross-section can be greatly improved. As a result, SEM dopant mapping could find a much more wide-spread application. © 2010 IOP Publishing Ltd.