TOF-SIMS allows for the detection of elemental, chemical state, and molecular information from surfaces of organic and inorganic materials with parallel mass detection of all elements within an investigated volume. It has high detection sensitivity in the range of parts per million (ppm) or even parts per billion (ppb) and can identify elements over large regions of interest, hundreds of micrometres in size, and small areas in the nanometric regime without requiring additional sample preparation. TOF-SIMS detectors that are compatible with high vacuum environments have become increasingly popular because of their easy integration with existing FIB instruments, which enables cost-effective correlative and complementary studies with other techniques such as scanning electron microscopy, energy dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS), electron backscatter diffraction (EBSD), atomic force microscopy (AFM), and Raman spectroscopy without breaking vacuum conditions. However, primary Ga+ beams used in FIB systems are less effective for the production of secondary ions compared to dedicated instruments equipped with reactive sources such as O2+ or Cs+. To address this issue, we propose modifying the surface of the sample with fluorine to facilitate secondary ion generation. Our research suggests that introducing fluorine gas during FIB sputtering can significantly increase SIMS signals for various elements, potentially by several orders of magnitude. We demonstrate the effectiveness of this approach through our analysis of both high-purity single elements and complex alloys with heterogeneous microstructures. Furthermore, our research suggests that co-injection of fluorine can mitigate the negative effects of preferential surface reoxidation during sputtering in standard SEM vacuum conditions, which typically leads to oxygen-enhanced ionization dominating the secondary ion signal. This improvement enables us to obtain FIB-TOF-SIMS maps showing the distribution of isotopes on the surface of the sample with much higher lateral resolution (up to one order of magnitude better) compared to standard SEM vacuum conditions [1].

[1] K. Wieczerzak, A. Priebe, I. Utke, J. Michler, Practical Aspects of Focused Ion Beam Time-of-Flight Secondary Ion Mass Spectrometry Analysis Enhanced by Fluorine Gas Coinjection, Chem. Mater. 33 (2021) 1581–1593.