In situ atomic force microscopy depth-corrected 3-dimensional focused ion beam based time-of-flight secondary ion mass spectroscopy: spatial resolution, surface roughness, oxidation

Abstract: Atomic force microscopy (AFM) is a well-known tool for studying surface roughness and to collect depth information about features on the top atomic layer of samples. By combining secondary ion mass spectroscopy (SIMS) with focused ion beam (FIB) milling in a scanning electron microscope (SEM), chemical information of sputtered structures can be visualized and located with high lateral and depth resolution. In this paper, a high vacuum (HV) compatible AFM has been installed in a TESCAN FIB-SEM instrument that was equipped with a time-of-flight secondary ion mass spectroscopy (ToF-SIMS) detector. To investigate the crater's depth caused by the ToF-SIMS sputtering, subsequent AFM measurements were performed on a multilayer vertical cavity surface emitting laser (VCSEL) sample. Surface roughness and milling depth were used to aid accurate 3D reconstruction of the sputtered volume's chemical composition. Achievable resolution, surface roughness during sputtering and surface oxidation issues are analysed. Thus, the integration of complementary detectors opens up the ability to determine the sample properties as well as to understand the influence of the analysis method on the sample surface during the analysis.