Image data fusion of SIMS and TOF-SIMS with a high spatial resolution is helpful to obtain a clearer score image by PCA. An image data fusion of SIMS and TOF-SMS in high spatial and mass resolution modes is also helpful in obtaining chemical information with a high spatial resolution image.
Based on the sparsity of SIM and TOF-SIMS, it is important to apply a sparse modeling technique to the data so as to minimize the TOF-SIMS data matrix. By applying the matrix decomposition technique to minimize the ranks of matrices, strong secondary ions will be obtained, which helps analyze unknown materials with weak peaks.
TOF-SIMS
TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) is a surface analytical technique using micro-focused Ga or Cs to get rid of molecules from the outermost surface of a sample.
Particles are usually removed from an atomic monolayer on a surface. These particles are accelerated afterward into the flight tube while their mass is dictated by measuring the exact time they reach a detector.
Three different operational modes are available through TOF-SIM. These include depth profiling, surface imaging, and surface spectroscopy. Analytical abilities of Time-of-Flight Secondary Ion Mass Spectrometry include the following:
- Retrospective analysis
- Depth profiling abilities
- A mass resolution of 0.00x amu
- Sub-micron imaging
- Limits for trace element detection
- A mass range starting from 0 to 10,000 amu
SIMS
SIMS, also called dynamic SIMS, is often used to get the depth profile of a material. If a beam of primary ions bombarding samples is continuous, then erosion of a sample surface and real-time sputtering of a sample will be simple within seconds, minutes, or even hours.
That dynamic part of this name comes from the simple fact that a sample is changed in real-time when exposed to a primary ion beam, and a visible sputter crater is created.
Like TOF-SIMS, D-SIMS systems use applied beams of neutral atoms or sputtering ions to scatter ion fragments from the sample surface. But unlike TOF-SIMS, which is usually regarded as a static-SIM method, D-SIMS measurements ablate quantities of materials from a surface.
This basically generates a signal for measurements and allows D-SIMS to quantify chemical composition. D-SIMS may acutely produce a sensitive depth profile of compositional distribution with an nm-scale vertical resolution.
The Key Difference between TOF-SIMS and SIMS
TOF-SIMS and SIMS are similar in terms of mass analysis of the secondary ions emitted by a primary ion beam. They greatly differ in terms of information obtained, equipment, and ion beam type. So it is basically a method with different uses.
SIM is simply a method, which may obtain concentration distribution of impurities with high sensitivity by bombarding samples with an active ion beam. It is usually used to get impurity and dopant depth distributions.
In contrast, TOF-SIMS refers to a technique, which can detect molecular and elemental data existing on the outer surface of samples with low primary ions. The method is used to get molecular data on the outer surface of a sample.
Concluding Remarks!
Measurement laboratories provide both TOF-SIMS and SIMS analysis services with affordable prices and fast results. If you have further questions about your samples or the suitability of the techniques, experts are always out there to help.
