Purpose and strength of the technique
- Identification of organic and anorganic compounds on surfaces
- Chemical Information on very thin layers or even sub monolayers
- Identification of contaminations
- Analysis of contucting and non conducting samples
- Measurement of depth profiles
- Mapping lateral distributions of compounds
- Detectable Elements: All elemental species and chemical compounds (Molecules)
- Detection Limit: Sub monolayer (ppm)
- Quantification: Only with reference standards
- Information Depth: About 1-3 monolayers
- Lateral Resolution: Down to 0,3 µm
- Depth Profiling: Yes
- Imaging: Yes
- Identification of organic compounds (like additives, contaminations) on sample surfaces
- Evaluation of cleaning processes
- Residue analysis
- Trace analysis on surfaces and inside layers (depth profiling)
- Detection of silicones on surfaces
- Composition of oils, greases or lubrication agents
- Failure analysis of delamination or adhesion problems
- Analysis of electrical contacts
The secondary ion mass spectrometry (TOF-SIMS) allows the measurement of the atomic and molecular composition of the uppermost 1-3 monolayers of a sample. In particular, it allows a unique identification of organic compounds on the surface of most materials. After special preparation liquids, greases, gels, pastes and similar substances can be studied alongside solids.
principle of operation
In a TOF-SIMS analysis, the surface to be examined is bombarded with a small ion dose. Through a kind of billiards game of these ions with the uppermost layers of the sample (atoms and molecules) avery small amount of material is removed from the sample surface. This material is analyzed using a mass spectrometer with respect to the masses of the individual fragments. So a mass spectrum of the sample surface is obtained. By evaluating this spectrum, the chemical composition of the surface is determined.
The detection sensitivity is in the range ppm or fmol. Quantification of the data is possible, but only by comparison with standard samples of known composition. However, semi-quantitative results can be obtained by comparative measurements between samples with similar chemical composition.
Usually spectra were measured locally during an investigation. These contain information about the chemical composition of the surface. It is also possible to use the TOF-SIMS as an imaging method. The technique can have a lateral resolution down to 300 nm under optimal conditions.
Through a continuous ion bombardment, sample material can also be removed and analyzed step by step. This is called depth profiling as well as dynamic SIMS. In this way, elemental information is measured as a function of depth.
By combining imaging and depth profiling the 3-dimensional chemical structure of a solid can be analyzed (3D probe microanalysis).
Requirements for the specimen
The requirements for sample preparation are quite low. Most samples can be analyzed directly without further pretreatment. In addition to solids, also powders and some liquids can be analyzed by a special preparation. The sample must be vacuum compatible. We will advise you if and how your sample can be analyzed by this method.
Since TOF-SIMS is a very sensitive method, the handling and packaging of the samples prior to analysis is very important. The nanoAnalytics GmbH provides you with detailed instructions for handling and packaging of samples.