TOF-SIMS

In TOF-SIMS an ion beam, referred to as the primary beam, is directed to the surface of a sample. When the primary beam hits the surface of the sample it causes the emission of ions originating from the top atomic layers of the sample. The emitted ions, referred to as secondary ions, are then accelerated in an electric field towards a detector. The time it takes for the secondary ions to reach the detector is measured and this time, the so-called time-of-flight, is related to the mass-to-charge ratio (m/z) of the ions, which in turn allows for the identification and quantification of the ion species. In this way information about the distribution and concentration of elements and molecular species of the very top layers of the sample surface can by analyzed with high sensitivity and spatial resolution. As the number of primary ions per unit area irradiated on the surface is small, the technique is considered near nondestructive. It is also possible to analyze the sample in depth, by so-called depth profiling. A sputter ion gun is then used in addition to the primary ion gun to etch away layer by layer of the surface while measuring.
The TOF-SIMS at CMAL is a TOF.SIMS5 from IONTOF. It is a classic TOF-SIMS that is equipped with a Bismuth nanoprobe gun that is typically used as the primary gun and three different sputter guns. The instrument is also equipped with a FIB for milling and automated 3D tomography as well as a sample preparation chamber that allows heating up to 800°C.

Instrument data   

• TOF.SIMS5 from IONTOF.
•  Time of flight analyzer range: up to 10 000 Da.
• Mass resolution (m/Δm): >10 000.
• Effective mass range: 1-2000 amu allowing for molecular information.
• Spatial resolution: down to 75 nm.
• Max rastering area: 500x500 μm (stiching possible for larger areas).
• Main primary gun: bismuth nanoprobe LMIG.
• Sputter guns: argon cluster GCIB mainly for sputtering and depth profiling of soft materials and polymers but also for surface cleaning. Oxygen and cesium mainly for reactive depth profiling of hard materials.
• Extended dynamic range depth profiling for accurate depth profiles with excellent linearity and reproducibility.
• Sample rotation for increased accuracy of very deep depth profiles.
• Flood gun for charge compensation.
• FIB for milling and sample indentation.
• Heating chamber to 800°C (connected to load lock).