Extraction of inhomogeneous chemical species from TOF-SIMS images with topographic artifacts by using correlation coefficient mapping

Abstract

It is often difficult to extract chemical distributions from TOF-SIMS (time-of-flight secondary ion mass spectrometry) images because intensity contrast can originate from several sources, including; (1) sample chemistry; (2) surface topography; (3) matrix effects; and (4) differential charging. Several methods, to extract the chemical distribution from TOF-SIMS images that are affected by surface topography, such as normalization by total ion intensity and PCA (principal component analysis), have been carried out. However, these methods have not been successful in all cases. In this study, we have tried to remove topographic artifacts by using correlation coefficient mapping (CCM) method. In order to investigate the usefulness of CCM, it was applied to three types of specimens that had topographical artifacts and/or chemical distributions. These results suggest that topographic artifacts can be removed in TOF-SIMS images using CCM, revealing more accurate inhomogeneous chemical distributions.