ToF-SIMS analysis

What is ToF-SIMS used for?

ToF-SIMS is a versatile technique that can be used to gather a wide range of information about the surface that is being analyzed. The method can be used to identify which elements, molecules, and compounds are present on a surface. This gives it applications across various fields from organic thin films to biological testing, material science, and more.

One of the most desirable qualities of ToF-SIMS is its ability to retroactively store the locations of the ions that are detected and digitally map them. This can be used to produce a visual representation of the sample on a very small scale.

How does ToF-SIMS work?

ToF-SIMS analysis begins by firing a focused beam of ions at the surface of a solid sample. As the ion beam collides with the surface, it causes further “secondary ions” and ionic clusters to be removed from the surface of the sample.

These secondary ions are then passed into a mass spectrometer. Here, the ions accelerate along a flight path, which is held under a vacuum to prevent interference. The respective masses of the individual ions will affect the length of time that it takes each ion to pass through the flight chamber. This process separates the ions and allows them to be detected individually. Once they reach the end of the spectrometer, the ions are registered by a detector, and the information is logged.

What is the difference between ToF-SIMS and SIMS analysis?

Secondary ion mass spectrometry (SIMS) refers more generally to the process of using a beam of ions to excite and remove secondary ions from the surface of a solid-state sample and then analyzing these ions through a form of mass spectrometry. ToF (Time of Flight) is one of these types of mass spectrometry and works by separating the ions based on how long it takes them to travel through the flight chamber.

SIMS can also be combined with other types of mass spectrometers, such as quadrupole or sector field. These will provide different sets of information and can be used to analyze surfaces in slightly different ways.

ToF-SIMS vs. XPS- what’s the difference in the techniques and uses?

X-ray photoelectron spectroscopy (XPS) is another analytical technique that is used to identify the elemental composition of a solid-state sample. It works by irradiating a sample with a beam of X-rays, which causes surface electrons to be excited and removed. These electrons are picked up by a detector that registers the energy of said electrons. This energy can be analyzed and gives an insight into the elemental composition of the surface.

The main difference between the results gathered from XPS and ToF-SIMS is that XPS is primarily used to determine the elements that make up a surface, whereas ToF-SIMS can provide additional information about molecules and clusters of atoms on the surface. Furthermore, XPS can be used for depth profiling of a sample, while ToF-SIMS is more appropriate for analyzing the surface - although it can be used for qualitative depth profiling.

Sample requirements and preparation

ToF-SIMS can be used on most solid-state sample types. Larger solid samples can be analyzed as is, and powdered samples can be pressed into an Indium plate before analysis. Generally, all ToF-SIMS samples should be handled very cautiously to avoid contamination. For example, plastic containers and tools should be avoided during handling.

Need an analysis?

Measurlabs offers thin film and semiconductor testing services with ToF-SIMS and various other techniques. You can read more about method selection for depth profiling and thin film thickness measurements on our material testing insights blog. Do not hesitate to contact our experts through the form below to request a quote for analysis services.