High Sensitivity of Fluorine Gas-Assisted FIB-TOF-SIMS for Chemical Characterization of Buried Sublayers in Thin Films

In this work, we present the potential of high vacuum-compatible time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors, which can be integrated within focused ion beam (FIB) instruments for precise and fast chemical characterization of thin films buried deep under the sample surface. This is demonstrated on complex multilayer systems composed of alternating ceramic and metallic layers with thicknesses varying from several nanometers to hundreds of nanometers. The typical problems of the TOF-SIMS technique, that is, low secondary ion signals and mass interference between ions having similar masses, were solved using a novel approach of co-injecting fluorine gas during the sample surface sputtering. In the most extreme case of the Al/Al2O3/Al/Al2O3/.../Al sample, a